Changeset e5d9274 for doc/theses
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- Jun 2, 2022, 3:11:21 PM (3 years ago)
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doc/theses/mubeen_zulfiqar_MMath/allocator.tex
r015925a re5d9274 29 29 llheap's design was reviewed and changed multiple times throughout the thesis. 30 30 Some of the rejected designs are discussed because they show the path to the final design (see discussion in \VRef{s:MultipleHeaps}). 31 Note, a few simple stests for a design choice were compared with the current best allocators to determine the viability of a design.31 Note, a few simple tests for a design choice were compared with the current best allocators to determine the viability of a design. 32 32 33 33 … … 37 37 These designs look at the allocation/free \newterm{fastpath}, \ie when an allocation can immediately return free storage or returned storage is not coalesced. 38 38 \paragraph{T:1 model} 39 \VRef[Figure]{f:T1SharedBuckets} shows one heap accessed by multiple kernel threads (KTs) using a bucket array, where smaller bucket sizes are N-shared acrossKTs.40 This design leverages the fact that 95\% of allocation requests are less than 1024 bytes and there are only 3--5different request sizes.39 \VRef[Figure]{f:T1SharedBuckets} shows one heap accessed by multiple kernel threads (KTs) using a bucket array, where smaller bucket sizes are shared among N KTs. 40 This design leverages the fact that usually the allocation requests are less than 1024 bytes and there are only a few different request sizes. 41 41 When KTs $\le$ N, the common bucket sizes are uncontented; 42 42 when KTs $>$ N, the free buckets are contented and latency increases significantly. … … 64 64 65 65 \paragraph{T:H model} 66 \VRef[Figure]{f:THSharedHeaps} shows a fixed number of heaps (N), each a local free pool, where the heaps are sharded across the KTs.66 \VRef[Figure]{f:THSharedHeaps} shows a fixed number of heaps (N), each a local free pool, where the heaps are sharded (distributed) across the KTs. 67 67 A KT can point directly to its assigned heap or indirectly through the corresponding heap bucket. 68 When KT $\le$ N, the heaps are uncontented;68 When KT $\le$ N, the heaps might be uncontented; 69 69 when KTs $>$ N, the heaps are contented. 70 70 In all cases, a KT must acquire/release a lock, contented or uncontented along the fast allocation path because a heap is shared. 71 By adjusting N upwards, this approach reduces contention but increases storage (time versus space);71 By increasing N, this approach reduces contention but increases storage (time versus space); 72 72 however, picking N is workload specific. 73 73 … … 109 109 Need to prevent preemption during a dynamic memory operation because of the \newterm{serially-reusable problem}. 110 110 \begin{quote} 111 A sequence of code that is guaranteed to run to completion before being invoked to accept another input is called serially-reusable code.~\cite{SeriallyReusable} 111 A sequence of code that is guaranteed to run to completion before being invoked to accept another input is called serially-reusable code.~\cite{SeriallyReusable}\label{p:SeriallyReusable} 112 112 \end{quote} 113 113 If a KT is preempted during an allocation operation, the operating system can schedule another KT on the same CPU, which can begin an allocation operation before the previous operation associated with this CPU has completed, invalidating heap correctness. … … 138 138 (See \VRef[Figure]{f:THSharedHeaps} but with a heap bucket per KT and no bucket or local-pool lock.) 139 139 Hence, immediately after a KT starts, its heap is created and just before a KT terminates, its heap is (logically) deleted. 140 Heaps are uncontended for a KTs memory operations to its heap (modulo operations on the global pool and ownership).140 Heaps are uncontended for a KTs memory operations as every KT has its own thread-local heap, modulo operations on the global pool and ownership. 141 141 142 142 Problems: 143 143 \begin{itemize} 144 144 \item 145 Need to know when a KT isstarts/terminates to create/delete its heap.145 Need to know when a KT starts/terminates to create/delete its heap. 146 146 147 147 \noindent … … 161 161 \noindent 162 162 In many concurrent applications, good performance is achieved with the number of KTs proportional to the number of CPUs. 163 Since the number of CPUs is relatively small, >~1024, and a heaprelatively small, $\approx$10K bytes (not including any associated freed storage), the worst-case external fragmentation is still small compared to the RAM available on large servers with many CPUs.163 Since the number of CPUs is relatively small, and a heap is also relatively small, $\approx$10K bytes (not including any associated freed storage), the worst-case external fragmentation is still small compared to the RAM available on large servers with many CPUs. 164 164 \item 165 165 There is the same serially-reusable problem with UTs migrating across KTs. … … 171 171 \noindent 172 172 The conclusion from this design exercise is: any atomic fence, atomic instruction (lock free), or lock along the allocation fastpath produces significant slowdown. 173 For the T:1 and T:H models, locking must exist along the allocation fastpath because the buckets or heaps m aybe shared by multiple threads, even when KTs $\le$ N.173 For the T:1 and T:H models, locking must exist along the allocation fastpath because the buckets or heaps might be shared by multiple threads, even when KTs $\le$ N. 174 174 For the T:H=CPU and 1:1 models, locking is eliminated along the allocation fastpath. 175 175 However, T:H=CPU has poor operating-system support to determine the CPU id (heap id) and prevent the serially-reusable problem for KTs. 176 176 More operating system support is required to make this model viable, but there is still the serially-reusable problem with user-level threading. 177 Leaving the 1:1 model with no atomic actions along the fastpath and no special operating-system support required.177 So the 1:1 model had no atomic actions along the fastpath and no special operating-system support requirements. 178 178 The 1:1 model still has the serially-reusable problem with user-level threading, which is addressed in \VRef{s:UserlevelThreadingSupport}, and the greatest potential for heap blowup for certain allocation patterns. 179 179 … … 212 212 Ideally latency is $O(1)$ with a small constant. 213 213 214 To obtain $O(1)$ internal latency means no searching on the allocation fastpath ,largely prohibits coalescing, which leads to external fragmentation.214 To obtain $O(1)$ internal latency means no searching on the allocation fastpath and largely prohibits coalescing, which leads to external fragmentation. 215 215 The mitigating factor is that most programs have well behaved allocation patterns, where the majority of allocation operations can be $O(1)$, and heap blowup does not occur without coalescing (although the allocation footprint may be slightly larger). 216 216 … … 257 257 llheap starts by creating an array of $N$ global heaps from storage obtained using @mmap@, where $N$ is the number of computer cores, that persists for program duration. 258 258 There is a global bump-pointer to the next free heap in the array. 259 When this array is exhausted, another array is allocated.260 There is a global top pointer for a heap intrusive linkto chain free heaps from terminated threads.261 When statistics are turned on, there is a global top pointer for a heap intrusive linkto chain \emph{all} the heaps, which is traversed to accumulate statistics counters across heaps using @malloc_stats@.259 When this array is exhausted, another array of heaps is allocated. 260 There is a global top pointer for a intrusive linked-list to chain free heaps from terminated threads. 261 When statistics are turned on, there is a global top pointer for a intrusive linked-list to chain \emph{all} the heaps, which is traversed to accumulate statistics counters across heaps using @malloc_stats@. 262 262 263 263 When a KT starts, a heap is allocated from the current array for exclusive use by the KT. 264 When a KT terminates, its heap is chained onto the heap free-list for reuse by a new KT, which prevents unbounded growth of heaps.265 The free heaps is astack so hot storage is reused first.266 Preserving all heaps created during the program lifetime, solves the storage lifetime problem,when ownership is used.264 When a KT terminates, its heap is chained onto the heap free-list for reuse by a new KT, which prevents unbounded growth of number of heaps. 265 The free heaps are stored on stack so hot storage is reused first. 266 Preserving all heaps, created during the program lifetime, solves the storage lifetime problem when ownership is used. 267 267 This approach wastes storage if a large number of KTs are created/terminated at program start and then the program continues sequentially. 268 268 llheap can be configured with object ownership, where an object is freed to the heap from which it is allocated, or object no-ownership, where an object is freed to the KT's current heap. 269 269 270 270 Each heap uses segregated free-buckets that have free objects distributed across 91 different sizes from 16 to 4M. 271 All objects in a bucket are of the same size. 271 272 The number of buckets used is determined dynamically depending on the crossover point from @sbrk@ to @mmap@ allocation using @mallopt( M_MMAP_THRESHOLD )@, \ie small objects managed by the program and large objects managed by the operating system. 272 273 Each free bucket of a specific size has the following two lists: … … 286 287 Quantizing is performed using a binary search over the ordered bucket array. 287 288 An optional optimization is fast lookup $O(1)$ for sizes < 64K from a 64K array of type @char@, where each element has an index to the corresponding bucket. 288 (Type @char@ restricts the number of bucket sizes to 256.) 289 The @char@ type restricts the number of bucket sizes to 256. 289 290 For $S$ > 64K, a binary search is used. 290 291 Then, the allocation storage is obtained from the following locations (in order), with increasing latency. … … 381 382 Then the corresponding bucket of the owner thread is computed for the deallocating thread, and the allocation is pushed onto the deallocating thread's bucket. 382 383 383 Finally, the llheap design funnels \label{p:FunnelRoutine} all allocation/deallocation operations through routines @malloc@/@free@, which are the only routines to directly access and manage the internal data structures of the heap.384 Finally, the llheap design funnels \label{p:FunnelRoutine} all allocation/deallocation operations through the @malloc@ and @free@ routines, which are the only routines to directly access and manage the internal data structures of the heap. 384 385 Other allocation operations, \eg @calloc@, @memalign@, and @realloc@, are composed of calls to @malloc@ and possibly @free@, and may manipulate header information after storage is allocated. 385 386 This design simplifies heap-management code during development and maintenance. … … 388 389 \subsection{Alignment} 389 390 390 All dynamic memory allocations musthave a minimum storage alignment for the contained object(s).391 Most dynamic memory allocations have a minimum storage alignment for the contained object(s). 391 392 Often the minimum memory alignment, M, is the bus width (32 or 64-bit) or the largest register (double, long double) or largest atomic instruction (DCAS) or vector data (MMMX). 392 393 In general, the minimum storage alignment is 8/16-byte boundary on 32/64-bit computers. 393 394 For consistency, the object header is normally aligned at this same boundary. 394 Larger alignments must be a power of 2, such page alignment (4/8K).395 Larger alignments must be a power of 2, such as page alignment (4/8K). 395 396 Any alignment request, N, $\le$ the minimum alignment is handled as a normal allocation with minimal alignment. 396 397 … … 400 401 \end{center} 401 402 The storage between @E@ and @H@ is chained onto the appropriate free list for future allocations. 402 Th is approach is also valid within any sufficiently large free block, where @E@ is the start of the free block, and any unused storage before @H@ or after the allocated object becomes free storage.403 The same approach is used for sufficiently large free blocks, where @E@ is the start of the free block, and any unused storage before @H@ or after the allocated object becomes free storage. 403 404 In this approach, the aligned address @A@ is the same as the allocated storage address @P@, \ie @P@ $=$ @A@ for all allocation routines, which simplifies deallocation. 404 405 However, if there are a large number of aligned requests, this approach leads to memory fragmentation from the small free areas around the aligned object. … … 407 408 Finally, this approach is incompatible with allocator designs that funnel allocation requests through @malloc@ as it directly manipulates management information within the allocator to optimize the space/time of a request. 408 409 409 Instead, llheap alignment is accomplished by making a \emph{pessimistic ally} allocation request for sufficient storage to ensure that \emph{both} the alignment and size request are satisfied, \eg:410 Instead, llheap alignment is accomplished by making a \emph{pessimistic} allocation request for sufficient storage to ensure that \emph{both} the alignment and size request are satisfied, \eg: 410 411 \begin{center} 411 412 \input{Alignment2} … … 424 425 \input{Alignment2Impl} 425 426 \end{center} 426 Since @malloc@ has a minimum alignment of @M@, @P@ $\neq$ @A@ only holds for alignments of @M@ or greater.427 Since @malloc@ has a minimum alignment of @M@, @P@ $\neq$ @A@ only holds for alignments greater than @M@. 427 428 When @P@ $\neq$ @A@, the minimum distance between @P@ and @A@ is @M@ bytes, due to the pessimistic storage-allocation. 428 429 Therefore, there is always room for an @M@-byte fake header before @A@. … … 439 440 \label{s:ReallocStickyProperties} 440 441 441 Allocation routine @realloc@ provides a memory-management pattern for shrinking/enlarging an existing allocation, while maintaining some or all of the object data, rather than performing the following steps manually.442 The allocation routine @realloc@ provides a memory-management pattern for shrinking/enlarging an existing allocation, while maintaining some or all of the object data, rather than performing the following steps manually. 442 443 \begin{flushleft} 443 444 \begin{tabular}{ll} … … 460 461 The realloc pattern leverages available storage at the end of an allocation due to bucket sizes, possibly eliminating a new allocation and copying. 461 462 This pattern is not used enough to reduce storage management costs. 462 In fact, if @oaddr@ is @nullptr@, @realloc@ does a @malloc@, so even the initial @malloc@ can be a @realloc@ for consistency in the pattern.463 In fact, if @oaddr@ is @nullptr@, @realloc@ does a @malloc@, so even the initial @malloc@ can be a @realloc@ for consistency in the allocation pattern. 463 464 464 465 The hidden problem for this pattern is the effect of zero fill and alignment with respect to reallocation. 465 466 Are these properties transient or persistent (``sticky'')? 466 For example, when memory is initially allocated by @calloc@ or @memalign@ with zero fill or alignment properties, respectively, what happens when those allocations are given to @realloc@ to change size .467 That is, if @realloc@ logically extends storage into unused bucket space or allocates new storage to satisfy a size change, are initial allocation properties preserve ?467 For example, when memory is initially allocated by @calloc@ or @memalign@ with zero fill or alignment properties, respectively, what happens when those allocations are given to @realloc@ to change size? 468 That is, if @realloc@ logically extends storage into unused bucket space or allocates new storage to satisfy a size change, are initial allocation properties preserved? 468 469 Currently, allocation properties are not preserved, so subsequent use of @realloc@ storage may cause inefficient execution or errors due to lack of zero fill or alignment. 469 470 This silent problem is unintuitive to programmers and difficult to locate because it is transient. … … 475 476 476 477 To preserve allocation properties requires storing additional information with an allocation, 477 The only available location is the header, where \VRef[Figure]{f:llheapNormalHeader} shows the llheap storage layout.478 The best available option is the header, where \VRef[Figure]{f:llheapNormalHeader} shows the llheap storage layout. 478 479 The header has two data field sized appropriately for 32/64-bit alignment requirements. 479 480 The first field is a union of three values: … … 487 488 \end{description} 488 489 The second field remembers the request size versus the allocation (bucket) size, \eg request 42 bytes which is rounded up to 64 bytes. 489 Since programmers think in request sizes rather than allocation sizes, the request size allows better generation of statistics or errors .490 Since programmers think in request sizes rather than allocation sizes, the request size allows better generation of statistics or errors and also helps in memory management. 490 491 491 492 \begin{figure} … … 496 497 \end{figure} 497 498 498 The low-order 3-bits of the first field are \emph{unused} for any stored values , whereas the second field may use all of its bits.499 The low-order 3-bits of the first field are \emph{unused} for any stored values as these values are 16-byte aligned by default, whereas the second field may use all of its bits. 499 500 The 3 unused bits are used to represent mapped allocation, zero filled, and alignment, respectively. 500 501 Note, the alignment bit is not used in the normal header and the zero-filled/mapped bits are not used in the fake header. … … 502 503 If no bits are on, it implies a basic allocation, which is handled quickly; 503 504 otherwise, the bits are analysed and appropriate actions are taken for the complex cases. 504 Since most allocations are basic, th is implementation results in a significant performance gainalong the allocation and free fastpath.505 Since most allocations are basic, they will take significantly less time as the memory operations will be done along the allocation and free fastpath. 505 506 506 507 … … 514 515 To locate all statistic counters, heaps are linked together in statistics mode, and this list is locked and traversed to sum all counters across heaps. 515 516 Note, the list is locked to prevent errors traversing an active list; 516 the statistics counters are not locked and can flicker during accumulation , which is not an issue with atomic read/write.517 the statistics counters are not locked and can flicker during accumulation. 517 518 \VRef[Figure]{f:StatiticsOutput} shows an example of statistics output, which covers all allocation operations and information about deallocating storage not owned by a thread. 518 519 No other memory allocator studied provides as comprehensive statistical information. 519 Finally, these statistics were invaluable during the development of this thesis for debugging and verifying correctness , and hence,should be equally valuable to application developers.520 Finally, these statistics were invaluable during the development of this thesis for debugging and verifying correctness and should be equally valuable to application developers. 520 521 521 522 \begin{figure} … … 547 548 Nevertheless, the checks detect many allocation problems. 548 549 There is an unfortunate problem in detecting unfreed storage because some library routines assume their allocations have life-time duration, and hence, do not free their storage. 549 For example, @printf@ allocates a 1024 buffer onfirst call and never deletes this buffer.550 For example, @printf@ allocates a 1024-byte buffer on the first call and never deletes this buffer. 550 551 To prevent a false positive for unfreed storage, it is possible to specify an amount of storage that is never freed (see @malloc_unfreed@ \VPageref{p:malloc_unfreed}), and it is subtracted from the total allocate/free difference. 551 552 Determining the amount of never-freed storage is annoying, but once done, any warnings of unfreed storage are application related. 552 553 553 Tests indicate only a 30\% performance increase when statistics \emph{and} debugging are enabled, and the latency cost for accumulating statistic is mitigated by limited calls, often only one at the end of the program.554 Tests indicate only a 30\% performance decrease when statistics \emph{and} debugging are enabled, and the latency cost for accumulating statistic is mitigated by limited calls, often only one at the end of the program. 554 555 555 556 … … 557 558 \label{s:UserlevelThreadingSupport} 558 559 559 The serially-reusable problem (see \V Ref{s:AllocationFastpath}) occurs for kernel threads in the ``T:H model, H = number of CPUs'' model and for user threads in the ``1:1'' model, where llheap uses the ``1:1'' model.560 The solution is to prevent interrupts that can result in CPU or KT change during operations that are logically critical sections.560 The serially-reusable problem (see \VPageref{p:SeriallyReusable}) occurs for kernel threads in the ``T:H model, H = number of CPUs'' model and for user threads in the ``1:1'' model, where llheap uses the ``1:1'' model. 561 The solution is to prevent interrupts that can result in a CPU or KT change during operations that are logically critical sections such as starting a memory operation on one KT and completing it on another. 561 562 Locking these critical sections negates any attempt for a quick fastpath and results in high contention. 562 563 For user-level threading, the serially-reusable problem appears with time slicing for preemptable scheduling, as the signal handler context switches to another user-level thread. 563 Without time slicing, a user thread performing a long computation can prevent execution(starve) other threads.564 To prevent starvation for a n allocation-active thread, \ie the time slice always triggers in an allocation critical-section for one thread, a thread-local \newterm{rollforward} flag is set in the signal handler when it aborts a time slice.564 Without time slicing, a user thread performing a long computation can prevent the execution of (starve) other threads. 565 To prevent starvation for a memory-allocation-intensive thread, \ie the time slice always triggers in an allocation critical-section for one thread so the thread never gets time sliced, a thread-local \newterm{rollforward} flag is set in the signal handler when it aborts a time slice. 565 566 The rollforward flag is tested at the end of each allocation funnel routine (see \VPageref{p:FunnelRoutine}), and if set, it is reset and a volunteer yield (context switch) is performed to allow other threads to execute. 566 567 567 llheap uses two techniques to detect when execution is in a allocation operation or routine called from allocation operation, to abort any time slice during this period.568 On the slowpath when executing expensive operations, like @sbrk@ or @mmap@, interrupts are disabled/enabled by setting thread-local flags so the signal handler aborts immediately.569 On the fastpath, disabling/enabling interrupts is too expensive as accessing thread-local storage can be expensive and notthread-safe.568 llheap uses two techniques to detect when execution is in an allocation operation or routine called from allocation operation, to abort any time slice during this period. 569 On the slowpath when executing expensive operations, like @sbrk@ or @mmap@, interrupts are disabled/enabled by setting kernel-thread-local flags so the signal handler aborts immediately. 570 On the fastpath, disabling/enabling interrupts is too expensive as accessing kernel-thread-local storage can be expensive and not user-thread-safe. 570 571 For example, the ARM processor stores the thread-local pointer in a coprocessor register that cannot perform atomic base-displacement addressing. 571 Hence, there is a window between loading the thread-local pointer from the coprocessor register into a normal register and adding the displacement when a time slice can move a thread.572 573 The fast technique definesa special code section and places all non-interruptible routines in this section.572 Hence, there is a window between loading the kernel-thread-local pointer from the coprocessor register into a normal register and adding the displacement when a time slice can move a thread. 573 574 The fast technique (with lower run time cost) is to define a special code section and places all non-interruptible routines in this section. 574 575 The linker places all code in this section into a contiguous block of memory, but the order of routines within the block is unspecified. 575 576 Then, the signal handler compares the program counter at the point of interrupt with the the start and end address of the non-interruptible section, and aborts if executing within this section and sets the rollforward flag. … … 577 578 Hence, for correctness, this approach requires inspection of generated assembler code for routines placed in the non-interruptible section. 578 579 This issue is mitigated by the llheap funnel design so only funnel routines and a few statistics routines are placed in the non-interruptible section and their assembler code examined. 579 These techniques are used in both the \uC and \CFA versions of llheap , whereboth of these systems have user-level threading.580 These techniques are used in both the \uC and \CFA versions of llheap as both of these systems have user-level threading. 580 581 581 582 … … 587 588 Programs can be statically or dynamically linked. 588 589 \item 589 The order the linker schedules startup code is poorly supported.590 The order in which the linker schedules startup code is poorly supported so it cannot be controlled entirely. 590 591 \item 591 592 Knowing a KT's start and end independently from the KT code is difficult. … … 600 601 Hence, some part of the @sbrk@ area may be used by the default allocator and statistics about allocation operations cannot be correct. 601 602 Furthermore, dynamic linking goes through trampolines, so there is an additional cost along the allocator fastpath for all allocation operations. 602 Testing showed up to a 5\% performance increase for dynamic linking overstatic linking, even when using @tls_model("initial-exec")@ so the dynamic loader can obtain tighter binding.603 Testing showed up to a 5\% performance decrease with dynamic linking as compared to static linking, even when using @tls_model("initial-exec")@ so the dynamic loader can obtain tighter binding. 603 604 604 605 All allocator libraries need to perform startup code to initialize data structures, such as the heap array for llheap. 605 The problem is getting initializ eddone before the first allocator call.606 The problem is getting initialization done before the first allocator call. 606 607 However, there does not seem to be mechanism to tell either the static or dynamic loader to first perform initialization code before any calls to a loaded library. 608 Also, initialization code of other libraries and the run-time environment may call memory allocation routines such as \lstinline{malloc}. 609 This compounds the situation as there is no mechanism to tell either the static or dynamic loader to first perform the initialization code of the memory allocator before any other initialization that may involve a dynamic memory allocation call. 607 610 As a result, calls to allocation routines occur without initialization. 608 611 To deal with this problem, it is necessary to put a conditional initialization check along the allocation fastpath to trigger initialization (singleton pattern). … … 641 644 Therefore, the constructor is useless for knowing when a KT starts because the KT must reference it, and the allocator does not control the application KT. 642 645 Fortunately, the singleton pattern needed for initializing the program KT also triggers KT allocator initialization, which can then reference @pgm_thread@ to call @threadManager@'s constructor, otherwise its destructor is not called. 643 Now when a KT terminates, @~ThreadManager@ is called to chain edit onto the global-heap free-stack, where @pgm_thread@ is set to true only for the program KT.646 Now when a KT terminates, @~ThreadManager@ is called to chain it onto the global-heap free-stack, where @pgm_thread@ is set to true only for the program KT. 644 647 The conditional destructor call prevents closing down the program heap, which must remain available because epilogue code may free more storage. 645 648 … … 660 663 bool traceHeapOff(); $\C{// stop printing allocation/free calls}$ 661 664 \end{lstlisting} 662 This kind of API is necessary to allow concurrent runtime systems to interact with differen cememory allocators in a consistent way.665 This kind of API is necessary to allow concurrent runtime systems to interact with different memory allocators in a consistent way. 663 666 664 667 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% … … 712 715 Most allocators use @nullptr@ to indicate an allocation failure, specifically out of memory; 713 716 hence the need to return an alternate value for a zero-sized allocation. 714 A different approach allowed by the C APIis to abort a program when out of memory and return @nullptr@ for a zero-sized allocation.717 A different approach allowed by @C API@ is to abort a program when out of memory and return @nullptr@ for a zero-sized allocation. 715 718 In theory, notifying the programmer of memory failure allows recovery; 716 719 in practice, it is almost impossible to gracefully recover when out of memory. … … 736 739 \paragraph{\lstinline{void * aalloc( size_t dim, size_t elemSize )}} 737 740 extends @calloc@ for allocating a dynamic array of objects without calculating the total size of array explicitly but \emph{without} zero-filling the memory. 738 @aalloc@ is significantly faster than @calloc@, which is the only alternative .741 @aalloc@ is significantly faster than @calloc@, which is the only alternative given by the standard memory-allocation routines. 739 742 740 743 \noindent\textbf{Usage} … … 825 828 \begin{itemize} 826 829 \item 827 @fd@: file s description.830 @fd@: file descriptor. 828 831 \end{itemize} 829 832 It returns the previous file descriptor. … … 832 835 \label{p:malloc_expansion} 833 836 set the amount (bytes) to extend the heap when there is insufficient free storage to service an allocation request. 834 It returns the heap extension size used throughout a program , \ie called once at heap initialization.837 It returns the heap extension size used throughout a program when requesting more memory from the system using @sbrk@ system-call, \ie called once at heap initialization. 835 838 836 839 \paragraph{\lstinline{size_t malloc_mmap_start()}} … … 915 918 \begin{itemize} 916 919 \item 917 naming: \CFA regular and @ttype@ polymorphism is used to encapsulate a wide range of allocation functionality into a single routine name, so programmers do not have to remember multiple routine names for different kinds of dynamic allocations.918 \item 919 named arguments: individual allocation properties are specified using postfix function call, so programmers dohave to remember parameter positions in allocation calls.920 \item 921 object size: like the \CFA C-styleinterface, programmers do not have to specify object size or cast allocation results.920 naming: \CFA regular and @ttype@ polymorphism (@ttype@ polymorphism in \CFA is similar to \CC variadic templates) is used to encapsulate a wide range of allocation functionality into a single routine name, so programmers do not have to remember multiple routine names for different kinds of dynamic allocations. 921 \item 922 named arguments: individual allocation properties are specified using postfix function call, so the programmers do not have to remember parameter positions in allocation calls. 923 \item 924 object size: like the \CFA's C-interface, programmers do not have to specify object size or cast allocation results. 922 925 \end{itemize} 923 926 Note, postfix function call is an alternative call syntax, using backtick @`@, where the argument appears before the function name, \eg … … 928 931 duration dur = 3@`@h + 42@`@m + 17@`@s; 929 932 \end{cfa} 930 @ttype@ polymorphism is similar to \CC variadic templates.931 933 932 934 \paragraph{\lstinline{T * alloc( ... )} or \lstinline{T * alloc( size_t dim, ... )}} 933 is overloaded with a variable number of specific allocation routines, or an integer dimension parameter followed by a variable number specific allocation routines. 935 is overloaded with a variable number of specific allocation operations, or an integer dimension parameter followed by a variable number of specific allocation operations. 936 These allocation operations can be passed as named arguments when calling the \lstinline{alloc} routine. 934 937 A call without parameters returns a dynamically allocated object of type @T@ (@malloc@). 935 938 A call with only the dimension (dim) parameter returns a dynamically allocated array of objects of type @T@ (@aalloc@). … … 980 983 5 5 5 -555819298 -555819298 // two undefined values 981 984 \end{lstlisting} 982 Examples 1 to 3 ,fill an object with a value or characters.983 Examples 4 to 7 ,fill an array of objects with values, another array, or part of an array.985 Examples 1 to 3 fill an object with a value or characters. 986 Examples 4 to 7 fill an array of objects with values, another array, or part of an array. 984 987 985 988 \subparagraph{\lstinline{S_resize(T) ?`resize( void * oaddr )}} … … 1015 1018 \subparagraph{\lstinline{S_realloc(T) ?`realloc( T * a ))}} 1016 1019 used to resize, realign, and fill, where the old object data is copied to the new object. 1017 The old object type must be the same as the new object type, since the value s used.1020 The old object type must be the same as the new object type, since the value is used. 1018 1021 Note, for @fill@, only the extra space after copying the data from the old object is filled with the given parameter. 1019 1022 For example: … … 1029 1032 \end{lstlisting} 1030 1033 Examples 2 to 3 change the alignment for the initial storage of @i@. 1031 The @13`fill@ forexample 3 does nothing because no extra space is added.1034 The @13`fill@ in example 3 does nothing because no extra space is added. 1032 1035 1033 1036 \begin{cfa}[numbers=left] … … 1044 1047 \end{lstlisting} 1045 1048 Examples 2 to 4 change the array size, alignment and fill for the initial storage of @ia@. 1046 The @13`fill@ forexample 3 does nothing because no extra space is added.1049 The @13`fill@ in example 3 does nothing because no extra space is added. 1047 1050 1048 1051 These \CFA allocation features are used extensively in the development of the \CFA runtime. -
doc/theses/mubeen_zulfiqar_MMath/background.tex
r015925a re5d9274 36 36 The management data starts with fixed-sized information in the static-data memory that references components in the dynamic-allocation memory. 37 37 The \newterm{storage data} is composed of allocated and freed objects, and \newterm{reserved memory}. 38 Allocated objects (light grey) are variable sized, and a llocated and maintained by the program;39 \ie only the program knows the location of allocated storage, not the memory allocator.38 Allocated objects (light grey) are variable sized, and are allocated and maintained by the program; 39 \ie only the memory allocator knows the location of allocated storage, not the program. 40 40 \begin{figure}[h] 41 41 \centering … … 49 49 if there are multiple reserved blocks, they are also chained together, usually internally. 50 50 51 Allocated and freed objects typicallyhave additional management data embedded within them.51 In some allocator designs, allocated and freed objects have additional management data embedded within them. 52 52 \VRef[Figure]{f:AllocatedObject} shows an allocated object with a header, trailer, and alignment padding and spacing around the object. 53 53 The header contains information about the object, \eg size, type, etc. … … 104 104 \VRef[Figure]{f:MemoryFragmentation} shows an example of how a small block of memory fragments as objects are allocated and deallocated over time. 105 105 Blocks of free memory become smaller and non-contiguous making them less useful in serving allocation requests. 106 Memory is highly fragmented when the sizes of most free blocks are unusable.106 Memory is highly fragmented when most free blocks are unusable because of their sizes. 107 107 For example, \VRef[Figure]{f:Contiguous} and \VRef[Figure]{f:HighlyFragmented} have the same quantity of external fragmentation, but \VRef[Figure]{f:HighlyFragmented} is highly fragmented. 108 108 If there is a request to allocate a large object, \VRef[Figure]{f:Contiguous} is more likely to be able to satisfy it with existing free memory, while \VRef[Figure]{f:HighlyFragmented} likely has to request more memory from the operating system. … … 137 137 The fewer bin-sizes, the fewer lists need to be searched and maintained; 138 138 however, the bin sizes are less likely to closely fit the requested object size, leading to more internal fragmentation. 139 The more bin -sizes, the longer the search and the less likely free objects are to be reused, leading to more external fragmentation and potentially heap blowup.139 The more bin sizes, the longer the search and the less likely free objects are to be reused, leading to more external fragmentation and potentially heap blowup. 140 140 A variation of the binning algorithm allows objects to be allocated to the requested size, but when an object is freed, it is placed on the free list of the next smallest or equal bin-size. 141 141 For example, with bin sizes of 8 and 16 bytes, a request for 12 bytes allocates only 12 bytes, but when the object is freed, it is placed on the 8-byte bin-list. … … 157 157 The principle of locality recognizes that programs tend to reference a small set of data, called a working set, for a certain period of time, where a working set is composed of temporal and spatial accesses~\cite{Denning05}. 158 158 Temporal clustering implies a group of objects are accessed repeatedly within a short time period, while spatial clustering implies a group of objects physically close together (nearby addresses) are accessed repeatedly within a short time period. 159 Temporal locality commonly occurs during an iterative computation with a fix set of disjoint variables, while spatial locality commonly occurs when traversing an array.159 Temporal locality commonly occurs during an iterative computation with a fixed set of disjoint variables, while spatial locality commonly occurs when traversing an array. 160 160 161 161 Hardware takes advantage of temporal and spatial locality through multiple levels of caching, \ie memory hierarchy. … … 328 328 For example, multiple heaps are managed in a pool, starting with a single or a fixed number of heaps that increase\-/decrease depending on contention\-/space issues. 329 329 At creation, a thread is associated with a heap from the pool. 330 When the thread attempts an allocation and its associated heap is locked (contention), it scans for an unlocked heap in the pool.330 In some implementations of this model, when the thread attempts an allocation and its associated heap is locked (contention), it scans for an unlocked heap in the pool. 331 331 If an unlocked heap is found, the thread changes its association and uses that heap. 332 332 If all heaps are locked, the thread may create a new heap, use it, and then place the new heap into the pool; … … 347 347 The management information in the static zone must be able to locate all heaps in the dynamic zone. 348 348 The management information for the heaps must reside in the dynamic-allocation zone if there are a variable number. 349 Each heap in the dynamic zone is composed of a list of afree objects and a pointer to its reserved memory.349 Each heap in the dynamic zone is composed of a list of free objects and a pointer to its reserved memory. 350 350 An alternative implementation is for all heaps to share one reserved memory, which requires a separate lock for the reserved storage to ensure mutual exclusion when acquiring new memory. 351 351 Because multiple threads can allocate/free/reallocate adjacent storage, all forms of false sharing may occur. … … 361 361 Multiple heaps increase external fragmentation as the ratio of heaps to threads increases, which can lead to heap blowup. 362 362 The external fragmentation experienced by a program with a single heap is now multiplied by the number of heaps, since each heap manages its own free storage and allocates its own reserved memory. 363 Additionally, objects freed by one heap cannot be reused by other threads , except indirectly by returning free memory to the operating system, which can be expensive.364 (Depending on how the operating system provides dynamic storage to an application, returning storage may be difficult or impossible, \eg the contiguous @sbrk@ area in Unix.) 363 Additionally, objects freed by one heap cannot be reused by other threads without increasing the cost of the memory operations, except indirectly by returning free memory to the operating system, which can be expensive. 364 Depending on how the operating system provides dynamic storage to an application, returning storage may be difficult or impossible, \eg the contiguous @sbrk@ area in Unix. 365 365 In the worst case, a program in which objects are allocated from one heap but deallocated to another heap means these freed objects are never reused. 366 366 … … 384 384 In contrast, the T:H model spreads each thread's objects over a larger area in different heaps. 385 385 Thread heaps can also eliminate allocator-induced active false-sharing, if memory is acquired so it does not overlap at crucial boundaries with memory for another thread's heap. 386 For example, assume page boundaries coincide with cache line boundaries, then if a thread heap always acquires pages of memory,no two threads share a page or cache line unless pointers are passed among them.386 For example, assume page boundaries coincide with cache line boundaries, if a thread heap always acquires pages of memory then no two threads share a page or cache line unless pointers are passed among them. 387 387 Hence, allocator-induced active false-sharing in \VRef[Figure]{f:AllocatorInducedActiveFalseSharing} cannot occur because the memory for thread heaps never overlaps. 388 388 389 When a thread terminates, there are two options for handling its heap.390 First is to free all objects in the heap to the global heap and destroy the thread heap.389 When a thread terminates, there are two options for handling its thread heap. 390 First is to free all objects in the thread heap to the global heap and destroy the thread heap. 391 391 Second is to place the thread heap on a list of available heaps and reuse it for a new thread in the future. 392 392 Destroying the thread heap immediately may reduce external fragmentation sooner, since all free objects are freed to the global heap and may be reused by other threads. 393 Alternatively, reusing thread heaps may improve performance if the inheriting thread makes similar allocation requests as the thread that previously held the thread heap because any unfreed storage is immediately accessible. .393 Alternatively, reusing thread heaps may improve performance if the inheriting thread makes similar allocation requests as the thread that previously held the thread heap because any unfreed storage is immediately accessible. 394 394 395 395 … … 417 417 When the user thread continues on the new kernel thread, it may have pointers into the previous kernel-thread's heap and hold locks associated with it. 418 418 To get the same kernel-thread safety, time slicing must be disabled/\-enabled around these operations, so the user thread cannot jump to another kernel thread. 419 However, eagerly disabling/enabling time-slicing on the allocation/deallocation fast path is expensive, because preemption is rare (10--100 milliseconds).419 However, eagerly disabling/enabling time-slicing on the allocation/deallocation fast path is expensive, because preemption does not happen that frequently. 420 420 Instead, techniques exist to lazily detect this case in the interrupt handler, abort the preemption, and return to the operation so it can complete atomically. 421 421 Occasionally ignoring a preemption should be benign, but a persistent lack of preemption can result in both short and long term starvation. 422 423 424 \begin{figure}425 \centering426 \subfigure[Ownership]{427 \input{MultipleHeapsOwnership}428 } % subfigure429 \hspace{0.25in}430 \subfigure[No Ownership]{431 \input{MultipleHeapsNoOwnership}432 } % subfigure433 \caption{Heap Ownership}434 \label{f:HeapsOwnership}435 \end{figure}436 422 437 423 … … 447 433 For the T:1/T:H models with or without ownership or the 1:1 model with ownership, a thread may free objects to different heaps, which makes each heap publicly accessible to all threads, called a \newterm{public heap}. 448 434 435 \begin{figure} 436 \centering 437 \subfigure[Ownership]{ 438 \input{MultipleHeapsOwnership} 439 } % subfigure 440 \hspace{0.25in} 441 \subfigure[No Ownership]{ 442 \input{MultipleHeapsNoOwnership} 443 } % subfigure 444 \caption{Heap Ownership} 445 \label{f:HeapsOwnership} 446 \end{figure} 447 449 448 \VRef[Figure]{f:MultipleHeapStorageOwnership} shows the effect of ownership on storage layout. 450 (For simplicity assume the heaps all use the same size of reserves storage.)449 (For simplicity, assume the heaps all use the same size of reserves storage.) 451 450 In contrast to \VRef[Figure]{f:MultipleHeapStorage}, each reserved area used by a heap only contains free storage for that particular heap because threads must return free objects back to the owner heap. 452 451 Again, because multiple threads can allocate/free/reallocate adjacent storage in the same heap, all forms of false sharing may occur. … … 473 472 While the returning thread can batch objects, batching across multiple heaps is complex and there is no obvious time when to push back to the owner heap. 474 473 It is better for returning threads to immediately return to the receiving thread's batch list as the receiving thread has better knowledge when to incorporate the batch list into its free pool. 475 Batching leverages the fact that most allocation patterns use the contention-free fast-path so locking on the batch list is rare for both the returning and receiving threads.476 477 It is possible for heaps to steal objects rather than return them and reallocating these objectswhen storage runs out on a heap.474 Batching leverages the fact that most allocation patterns use the contention-free fast-path, so locking on the batch list is rare for both the returning and receiving threads. 475 476 It is possible for heaps to steal objects rather than return them and then reallocate these objects again when storage runs out on a heap. 478 477 However, stealing can result in passive false-sharing. 479 478 For example, in \VRef[Figure]{f:AllocatorInducedPassiveFalseSharing}, Object$_2$ may be deallocated to Thread$_2$'s heap initially. … … 485 484 486 485 Bracketing every allocation with headers/trailers can result in significant internal fragmentation, as shown in \VRef[Figure]{f:ObjectHeaders}. 487 Especially if the headers contain redundant management information, \eg object size may be the same for many objects because programs only allocate a small set of object sizes.486 Especially if the headers contain redundant management information, then storing that information is a waste of storage, \eg object size may be the same for many objects because programs only allocate a small set of object sizes. 488 487 As well, it can result in poor cache usage, since only a portion of the cache line is holding useful information from the program's perspective. 489 488 Spatial locality can also be negatively affected leading to poor cache locality~\cite{Feng05}: … … 660 659 With local free-lists in containers, as in \VRef[Figure]{f:LocalFreeListWithinContainers}, the container is simply removed from one heap's free list and placed on the new heap's free list. 661 660 Thus, when using local free-lists, the operation of moving containers is reduced from $O(N)$ to $O(1)$. 662 The cost is adding information to aheader, which increases the header size, and therefore internal fragmentation.661 However, there is the additional storage cost in the header, which increases the header size, and therefore internal fragmentation. 663 662 664 663 \begin{figure} … … 689 688 The main goal of the hybrid approach is to eliminate locking on thread-local allocation/deallocation, while providing ownership to prevent heap blowup. 690 689 In the hybrid approach, a thread first allocates from its private heap and second from its public heap if no free memory exists in the private heap. 691 Similarly, a thread first deallocates an object its private heap, and second to the public heap.690 Similarly, a thread first deallocates an object to its private heap, and second to the public heap. 692 691 Both private and public heaps can allocate/deallocate to/from the global heap if there is no free memory or excess free memory, although an implementation may choose to funnel all interaction with the global heap through one of the heaps. 693 692 Note, deallocation from the private to the public (dashed line) is unlikely because there is no obvious advantages unless the public heap provides the only interface to the global heap. -
doc/theses/mubeen_zulfiqar_MMath/benchmarks.tex
r015925a re5d9274 12 12 \item[Benchmarks] 13 13 are a suite of application programs (SPEC CPU/WEB) that are exercised in a common way (inputs) to find differences among underlying software implementations associated with an application (compiler, memory allocator, web server, \etc). 14 The applications are suppose to represent common execution patterns that need to perform well with respect to an underlying software implementation.14 The applications are supposed to represent common execution patterns that need to perform well with respect to an underlying software implementation. 15 15 Benchmarks are often criticized for having overlapping patterns, insufficient patterns, or extraneous code that masks patterns. 16 16 \item[Micro-Benchmarks] … … 26 26 27 27 This thesis designs and examines a new set of micro-benchmarks for memory allocators that test a variety of allocation patterns, each with multiple tuning parameters. 28 The aim of the micro-benchmark suite is to create a set of programs that can evaluate a memory allocator based on the key performance m atrices such as speed, memory overhead, and cache performance.28 The aim of the micro-benchmark suite is to create a set of programs that can evaluate a memory allocator based on the key performance metrics such as speed, memory overhead, and cache performance. 29 29 % These programs can be taken as a standard to benchmark an allocator's basic goals. 30 30 These programs give details of an allocator's memory overhead and speed under certain allocation patterns. 31 The allocation patterns are configurable (adjustment knobs) to observe an allocator's performance across a spectrum of events for a desired allocation pattern, which is seldom possible with benchmark programs.31 The allocation patterns are configurable (adjustment knobs) to observe an allocator's performance across a spectrum allocation patterns, which is seldom possible with benchmark programs. 32 32 Each micro-benchmark program has multiple control knobs specified by command-line arguments. 33 33 34 The new micro-benchmark suite measures performance by allocating dynamic objects and measuring specific m atrices.34 The new micro-benchmark suite measures performance by allocating dynamic objects and measuring specific metrics. 35 35 An allocator's speed is benchmarked in different ways, as are issues like false sharing. 36 36 … … 40 40 Modern memory allocators, such as llheap, must handle multi-threaded programs at the KT and UT level. 41 41 The following multi-threaded micro-benchmarks are presented to give a sense of prior work~\cite{Berger00} at the KT level. 42 None of the prior work address multi-threading at the UT level.42 None of the prior work addresses multi-threading at the UT level. 43 43 44 44 … … 47 47 This benchmark stresses the ability of the allocator to handle different threads allocating and deallocating independently. 48 48 There is no interaction among threads, \ie no object sharing. 49 Each thread repeatedly allocate 100,000 \emph{8-byte} objects then deallocates them in the order they were allocated.50 Runtime of the benchmark evaluates its efficiency.49 Each thread repeatedly allocates 100,000 \emph{8-byte} objects then deallocates them in the order they were allocated. 50 The execution time of the benchmark evaluates its efficiency. 51 51 52 52 … … 63 63 Before the thread terminates, it passes its array of 10,000 objects to a new child thread to continue the process. 64 64 The number of thread generations varies depending on the thread speed. 65 It calculates memory operations per second as an indicator of memory allocator's performance.65 It calculates memory operations per second as an indicator of the memory allocator's performance. 66 66 67 67 … … 75 75 \label{s:ChurnBenchmark} 76 76 77 The churn benchmark measures the runtime speed of an allocator in a multi-threaded scen erio, where each thread extensively allocates and frees dynamic memory.77 The churn benchmark measures the runtime speed of an allocator in a multi-threaded scenario, where each thread extensively allocates and frees dynamic memory. 78 78 Only @malloc@ and @free@ are used to eliminate any extra cost, such as @memcpy@ in @calloc@ or @realloc@. 79 Churn simulates a memory intensive program thatcan be tuned to create different scenarios.79 Churn simulates a memory intensive program and can be tuned to create different scenarios. 80 80 81 81 \VRef[Figure]{fig:ChurnBenchFig} shows the pseudo code for the churn micro-benchmark. … … 133 133 When threads share a cache line, frequent reads/writes to their cache-line object causes cache misses, which cause escalating delays as cache distance increases. 134 134 135 Cache thrash tries to create a scen erio that leads to false sharing, if the underlying memory allocator is allocating dynamic memory to multiple threads on the same cache lines.135 Cache thrash tries to create a scenario that leads to false sharing, if the underlying memory allocator is allocating dynamic memory to multiple threads on the same cache lines. 136 136 Ideally, a memory allocator should distance the dynamic memory region of one thread from another. 137 137 Having multiple threads allocating small objects simultaneously can cause a memory allocator to allocate objects on the same cache line, if its not distancing the memory among different threads. … … 141 141 Each worker thread allocates an object and intensively reads/writes it for M times to possible invalidate cache lines that may interfere with other threads sharing the same cache line. 142 142 Each thread repeats this for N times. 143 The main thread measures the total time taken tofor all worker threads to complete.144 Worker threads sharing cache lines with each other willtake longer.143 The main thread measures the total time taken for all worker threads to complete. 144 Worker threads sharing cache lines with each other are expected to take longer. 145 145 146 146 \begin{figure} … … 156 156 signal workers to free 157 157 ... 158 print addresses from each $thread$159 158 Worker Thread$\(_1\)$ 160 allocate, write, read, free161 warmup memory in chunkc of 16 bytes162 ...163 malloc N objects164 ...165 free objects166 return object address to Main Thread159 warm up memory in chunks of 16 bytes 160 ... 161 For N 162 malloc an object 163 read/write the object M times 164 free the object 165 ... 167 166 Worker Thread$\(_2\)$ 168 167 // same as Worker Thread$\(_1\)$ … … 191 190 192 191 The cache-scratch micro-benchmark measures allocator-induced passive false-sharing as illustrated in \VRef{s:AllocatorInducedPassiveFalseSharing}. 193 As forcache thrash, if memory is allocated for multiple threads on the same cache line, this can significantly slow down program performance.192 As with cache thrash, if memory is allocated for multiple threads on the same cache line, this can significantly slow down program performance. 194 193 In this scenario, the false sharing is being caused by the memory allocator although it is started by the program sharing an object. 195 194 … … 202 201 Cache scratch tries to create a scenario that leads to false sharing and should make the memory allocator preserve the program-induced false sharing, if it does not return a freed object to its owner thread and, instead, re-uses it instantly. 203 202 An allocator using object ownership, as described in section \VRef{s:Ownership}, is less susceptible to allocator-induced passive false-sharing. 204 If the object is returned to the thread who owns it, then the thread that gets a new objectis less likely to be on the same cache line.203 If the object is returned to the thread that owns it, then the new object that the thread gets is less likely to be on the same cache line. 205 204 206 205 \VRef[Figure]{fig:benchScratchFig} shows the pseudo code for the cache-scratch micro-benchmark. … … 224 223 signal workers to free 225 224 ... 226 print addresses from each $thread$227 225 Worker Thread$\(_1\)$ 228 allocate, write, read, free 229 warmup memory in chunkc of 16 bytes 230 ... 231 for ( N ) 232 free an object passed by Main Thread 226 warmup memory in chunks of 16 bytes 227 ... 228 free the object passed by the Main Thread 229 For N 233 230 malloc new object 234 ...235 free objects236 return new object addresses to Main Thread231 read/write the object M times 232 free the object 233 ... 237 234 Worker Thread$\(_2\)$ 238 235 // same as Worker Thread$\(_1\)$ … … 248 245 249 246 Similar to benchmark cache thrash in section \VRef{sec:benchThrashSec}, different cache access scenarios can be created using the following command-line arguments. 250 \begin{description}[ itemsep=0pt,parsep=0pt]247 \begin{description}[topsep=0pt,itemsep=0pt,parsep=0pt] 251 248 \item[threads:] 252 249 number of threads (K). … … 262 259 \subsection{Speed Micro-Benchmark} 263 260 \label{s:SpeedMicroBenchmark} 261 \vspace*{-4pt} 264 262 265 263 The speed benchmark measures the runtime speed of individual and sequences of memory allocation routines: 266 \begin{enumerate}[ itemsep=0pt,parsep=0pt]264 \begin{enumerate}[topsep=-5pt,itemsep=0pt,parsep=0pt] 267 265 \item malloc 268 266 \item realloc … … 332 330 \VRef[Figure]{fig:MemoryBenchFig} shows the pseudo code for the memory micro-benchmark. 333 331 It creates a producer-consumer scenario with K producer threads and each producer has M consumer threads. 334 A producer has a separate buffer for each consumer and allocates N objects of random sizes following a settable distribution for each consumer.332 A producer has a separate buffer for each consumer and allocates N objects of random sizes following a configurable distribution for each consumer. 335 333 A consumer frees these objects. 336 334 After every memory operation, program memory usage is recorded throughout the runtime. -
doc/theses/mubeen_zulfiqar_MMath/conclusion.tex
r015925a re5d9274 17 17 % ==================== 18 18 19 The goal of this thesis was to build a low-latency memory allocator for both KT and UT multi-threads systems, which is competitive with the best current memory allocators,while extending the feature set of existing and new allocator routines.19 The goal of this thesis was to build a low-latency (or high bandwidth) memory allocator for both KT and UT multi-threading systems that is competitive with the best current memory allocators while extending the feature set of existing and new allocator routines. 20 20 The new llheap memory-allocator achieves all of these goals, while maintaining and managing sticky allocation information without a performance loss. 21 21 Hence, it becomes possible to use @realloc@ frequently as a safe operation, rather than just occasionally. 22 22 Furthermore, the ability to query sticky properties and information allows programmers to write safer programs, as it is possible to dynamically match allocation styles from unknown library routines that return allocations. 23 23 24 Extending the C allocation API with @resize@, advanced @realloc@, @aalloc@, @amemalign@, and @cmemalign@ means programmers do not make mistakes writing theses useful allocation operations.24 Extending the C allocation API with @resize@, advanced @realloc@, @aalloc@, @amemalign@, and @cmemalign@ means programmers do not have to do these useful allocation operations themselves. 25 25 The ability to use \CFA's advanced type-system (and possibly \CC's too) to have one allocation routine with completely orthogonal sticky properties shows how far the allocation API can be pushed, which increases safety and greatly simplifies programmer's use of dynamic allocation. 26 26 27 27 Providing comprehensive statistics for all allocation operations is invaluable in understanding and debugging a program's dynamic behaviour. 28 No other memory allocator provides comprehensive statistics gathering.28 No other memory allocator provides such comprehensive statistics gathering. 29 29 This capability was used extensively during the development of llheap to verify its behaviour. 30 30 As well, providing a debugging mode where allocations are checked, along with internal pre/post conditions and invariants, is extremely useful, especially for students. 31 While not as powerful as the @valgrind@ interpreter, a large number of allocation smistakes are detected.31 While not as powerful as the @valgrind@ interpreter, a large number of allocation mistakes are detected. 32 32 Finally, contention-free statistics gathering and debugging have a low enough cost to be used in production code. 33 33 … … 36 36 37 37 Starting a micro-benchmark test-suite for comparing allocators, rather than relying on a suite of arbitrary programs, has been an interesting challenge. 38 The current micro-benchmarks allow some understand of allocator implementation properties without actually looking at the implementation.38 The current micro-benchmarks allow some understanding of allocator implementation properties without actually looking at the implementation. 39 39 For example, the memory micro-benchmark quickly identified how several of the allocators work at the global level. 40 40 It was not possible to show how the micro-benchmarks adjustment knobs were used to tune to an interesting test point. … … 45 45 46 46 A careful walk-though of the allocator fastpath should yield additional optimizations for a slight performance gain. 47 In particular, looking atthe implementation of rpmalloc, which is often the fastest allocator,47 In particular, analysing the implementation of rpmalloc, which is often the fastest allocator, 48 48 49 The micro-benchmark sproject requires more testing and analysis.50 Additional allocation s patterns are needed to extract meaningful information about allocators, and within allocation patterns, what are the besttuning knobs.49 The micro-benchmark project requires more testing and analysis. 50 Additional allocation patterns are needed to extract meaningful information about allocators, and within allocation patterns, what are the most useful tuning knobs. 51 51 Also, identifying ways to visualize the results of the micro-benchmarks is a work in progress. 52 52 53 After llheap is made available on gitHub, interacting with its users to locate problems and improvements,will make llbench a more robust memory allocator.54 As well, feedback from the \uC and \CFA projects, which have adopted llheap for their memory allocator, will provide additional feedback.53 After llheap is made available on GitHub, interacting with its users to locate problems and improvements will make llbench a more robust memory allocator. 54 As well, feedback from the \uC and \CFA projects, which have adopted llheap for their memory allocator, will provide additional information. -
doc/theses/mubeen_zulfiqar_MMath/figures/Header.fig
r015925a re5d9274 20 20 2 1 1 1 0 7 50 -1 -1 4.000 0 0 -1 0 0 2 21 21 3300 1500 3300 2400 22 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 23 4200 1800 6600 1800 6600 2100 4200 2100 4200 1800 22 24 2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 3 23 25 1 1 1.00 45.00 90.00 24 4 050 2625 3750 2625 3750 240026 4200 2775 3750 2775 3750 1725 25 27 2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 3 26 28 1 1 1.00 45.00 90.00 27 4050 2850 3450 2850 3450 2400 28 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 29 4200 1800 6600 1800 6600 2100 4200 2100 4200 1800 29 4200 2550 4050 2550 4050 1725 30 2 1 0 1 0 7 50 -1 -1 4.000 0 0 -1 1 0 3 31 1 1 1.00 45.00 90.00 32 4200 3000 3450 3000 3450 2025 30 33 4 0 0 50 -1 0 12 0.0000 2 180 1185 1875 1725 bucket pointer\001 31 34 4 0 0 50 -1 0 12 0.0000 2 180 1005 1875 2025 mapped size\001 32 35 4 0 0 50 -1 0 12 0.0000 2 135 1215 1875 2325 next free block\001 33 36 4 2 0 50 -1 0 12 0.0000 2 135 480 1725 2025 union\001 34 4 1 0 50 -1 0 12 0.0000 2 135 270 3775 2325 0/1\00135 4 1 0 50 -1 0 12 0.0000 2 135 270 3475 2325 0/1\00136 37 4 1 0 50 -1 0 12 0.0000 2 180 945 5400 2025 request size\001 37 38 4 1 0 50 -1 0 12 0.0000 2 180 765 5400 1425 4/8-bytes\001 38 39 4 1 0 50 -1 0 12 0.0000 2 180 765 3000 1425 4/8-bytes\001 39 4 0 0 50 -1 0 12 0.0000 2 135 825 4125 2700 zero filled\001 40 4 0 0 50 -1 0 12 0.0000 2 180 1515 4125 2925 mapped allocation\001 40 4 1 0 50 -1 0 12 0.0000 2 135 270 3475 2025 0/1\001 41 4 1 0 50 -1 0 12 0.0000 2 135 270 3775 1725 0/1\001 42 4 1 0 50 -1 0 12 0.0000 2 135 270 4075 1725 0/1\001 43 4 0 0 50 -1 0 12 0.0000 2 180 1515 4275 3075 mapped allocation\001 44 4 0 0 50 -1 0 12 0.0000 2 135 825 4275 2850 zero filled\001 45 4 0 0 50 -1 0 12 0.0000 2 180 1920 4275 2625 alignment (fake header)\001 -
doc/theses/mubeen_zulfiqar_MMath/figures/MultipleHeapsNoOwnership.fig
r015925a re5d9274 1 #FIG 3.2 Produced by xfig version 3.2. 51 #FIG 3.2 Produced by xfig version 3.2.7b 2 2 Landscape 3 3 Center 4 4 Inches 5 Letter 5 Letter 6 6 100.00 7 7 Single … … 11 11 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 12 12 1200 2100 1500 2100 1500 1800 1200 1800 1200 2100 13 4 1 0 50 -1 0 11 0.0000 2 1 95 495 1350 2025 H$_1$\00113 4 1 0 50 -1 0 11 0.0000 2 165 495 1350 2025 H$_1$\001 14 14 -6 15 15 6 1950 1800 2550 2100 16 16 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 17 17 2100 2100 2400 2100 2400 1800 2100 1800 2100 2100 18 4 1 0 50 -1 0 11 0.0000 2 1 95 495 2250 2025 H$_2$\00118 4 1 0 50 -1 0 11 0.0000 2 165 495 2250 2025 H$_2$\001 19 19 -6 20 20 1 3 0 1 0 7 50 -1 -1 0.000 0 -0.0000 1350 1350 150 150 1350 1350 1500 1350 21 21 1 3 0 1 0 7 50 -1 -1 0.000 0 -0.0000 2250 1350 150 150 2250 1350 2400 1350 22 22 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 23 0 01.00 45.00 90.0024 0 01.00 45.00 90.0023 1 1 1.00 45.00 90.00 24 1 1 1.00 45.00 90.00 25 25 1275 1800 1275 1500 26 2 1 0 1 0 750 -1 -1 0.000 0 0 -1 1 0 227 0 01.00 45.00 90.0026 2 1 0 1 0 0 50 -1 -1 0.000 0 0 -1 1 0 2 27 1 1 1.00 45.00 90.00 28 28 1425 1500 1425 1800 29 29 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 1 2 30 0 01.00 45.00 90.0030 1 1 1.00 45.00 90.00 31 31 1425 1500 2175 1800 32 32 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 1 2 33 0 01.00 45.00 90.0033 1 1 1.00 45.00 90.00 34 34 2175 1500 1425 1800 35 35 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 0 2 36 0 01.00 45.00 90.0036 1 1 1.00 45.00 90.00 37 37 2175 1500 2175 1800 38 38 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 39 0 01.00 45.00 90.0040 0 01.00 45.00 90.0039 1 1 1.00 45.00 90.00 40 1 1 1.00 45.00 90.00 41 41 2325 1800 2325 1500 42 4 1 0 50 -1 0 11 0.0000 2 1 95 465 1350 1425 T$_1$\00143 4 1 0 50 -1 0 11 0.0000 2 1 95 465 2250 1425 T$_2$\00142 4 1 0 50 -1 0 11 0.0000 2 165 465 1350 1425 T$_1$\001 43 4 1 0 50 -1 0 11 0.0000 2 165 465 2250 1425 T$_2$\001 -
doc/theses/mubeen_zulfiqar_MMath/figures/MultipleHeapsOwnership.fig
r015925a re5d9274 1 #FIG 3.2 Produced by xfig version 3.2. 51 #FIG 3.2 Produced by xfig version 3.2.7b 2 2 Landscape 3 3 Center 4 4 Inches 5 Letter 5 Letter 6 6 100.00 7 7 Single … … 11 11 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 12 12 1200 2100 1500 2100 1500 1800 1200 1800 1200 2100 13 4 1 0 50 -1 0 11 0.0000 2 1 95 495 1350 2025 H$_1$\00113 4 1 0 50 -1 0 11 0.0000 2 165 495 1350 2025 H$_1$\001 14 14 -6 15 15 6 1950 1800 2550 2100 16 16 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 17 17 2100 2100 2400 2100 2400 1800 2100 1800 2100 2100 18 4 1 0 50 -1 0 11 0.0000 2 1 95 495 2250 2025 H$_2$\00118 4 1 0 50 -1 0 11 0.0000 2 165 495 2250 2025 H$_2$\001 19 19 -6 20 20 1 3 0 1 0 7 50 -1 -1 0.000 0 -0.0000 1350 1350 150 150 1350 1350 1500 1350 21 21 1 3 0 1 0 7 50 -1 -1 0.000 0 -0.0000 2250 1350 150 150 2250 1350 2400 1350 22 22 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 23 0 01.00 45.00 90.0024 0 01.00 45.00 90.0023 1 1 1.00 45.00 90.00 24 1 1 1.00 45.00 90.00 25 25 2175 1500 1425 1800 26 26 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 27 0 0 1.00 45.00 90.00 28 0 0 1.00 45.00 90.00 29 1425 1500 2175 1800 30 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 31 0 0 1.00 45.00 90.00 32 0 0 1.00 45.00 90.00 27 1 1 1.00 45.00 90.00 28 1 1 1.00 45.00 90.00 33 29 1275 1800 1275 1500 34 30 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 35 0 01.00 45.00 90.0036 0 01.00 45.00 90.0031 1 1 1.00 45.00 90.00 32 1 1 1.00 45.00 90.00 37 33 2325 1800 2325 1500 38 4 1 0 50 -1 0 11 0.0000 2 195 465 2250 1425 T$_2$\001 39 4 1 0 50 -1 0 11 0.0000 2 195 465 1350 1425 T$_1$\001 34 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 35 1 1 1.00 45.00 90.00 36 1 1 1.00 45.00 90.00 37 1425 1500 2175 1800 38 4 1 0 50 -1 0 11 0.0000 2 165 465 2250 1425 T$_2$\001 39 4 1 0 50 -1 0 11 0.0000 2 165 465 1350 1425 T$_1$\001 -
doc/theses/mubeen_zulfiqar_MMath/figures/PerThreadHeap.fig
r015925a re5d9274 1 #FIG 3.2 Produced by xfig version 3.2. 51 #FIG 3.2 Produced by xfig version 3.2.7b 2 2 Landscape 3 3 Center 4 4 Inches 5 Letter 5 Letter 6 6 100.00 7 7 Single … … 11 11 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 12 12 2700 1800 3000 1800 3000 2100 2700 2100 2700 1800 13 4 1 0 50 -1 0 11 0.0000 2 1 35135 2850 2025 G\00113 4 1 0 50 -1 0 11 0.0000 2 120 135 2850 2025 G\001 14 14 -6 15 15 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 1350 1350 150 150 1350 1350 1500 1350 … … 17 17 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 2250 1350 150 150 2250 1350 2400 1350 18 18 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 19 0 01.00 45.00 90.0020 0 01.00 45.00 90.0019 1 1 1.00 45.00 90.00 20 1 1 1.00 45.00 90.00 21 21 1350 1500 1350 1800 22 22 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 … … 27 27 2100 1800 2400 1800 2400 2100 2100 2100 2100 1800 28 28 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 29 0 01.00 45.00 90.0030 0 01.00 45.00 90.0029 1 1 1.00 45.00 90.00 30 1 1 1.00 45.00 90.00 31 31 1800 1500 1800 1800 32 32 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 33 0 01.00 45.00 90.0034 0 01.00 45.00 90.0033 1 1 1.00 45.00 90.00 34 1 1 1.00 45.00 90.00 35 35 2250 1500 2250 1800 36 4 1 0 50 -1 0 11 0.0000 2 1 95 1320 2550 2025 $\\Leftrightarrow$\00137 4 1 0 50 -1 0 11 0.0000 2 1 95 1320 3150 2025 $\\Leftrightarrow$\00138 4 0 0 50 -1 0 11 0.0000 2 1 35240 3300 2025 OS\00139 4 1 0 50 -1 0 11 0.0000 2 1 95 495 1350 2025 H$_1$\00140 4 1 0 50 -1 0 11 0.0000 2 1 95 465 1350 1425 T$_1$\00141 4 1 0 50 -1 0 11 0.0000 2 1 95 495 1800 2025 H$_2$\00142 4 1 0 50 -1 0 11 0.0000 2 1 95 465 1800 1425 T$_2$\00143 4 1 0 50 -1 0 11 0.0000 2 1 95 495 2250 2025 H$_3$\00144 4 1 0 50 -1 0 11 0.0000 2 1 95 465 2250 1425 T$_3$\00136 4 1 0 50 -1 0 11 0.0000 2 180 1260 2550 2025 $\\Leftrightarrow$\001 37 4 1 0 50 -1 0 11 0.0000 2 180 1260 3150 2025 $\\Leftrightarrow$\001 38 4 0 0 50 -1 0 11 0.0000 2 120 240 3300 2025 OS\001 39 4 1 0 50 -1 0 11 0.0000 2 165 495 1350 2025 H$_1$\001 40 4 1 0 50 -1 0 11 0.0000 2 165 465 1350 1425 T$_1$\001 41 4 1 0 50 -1 0 11 0.0000 2 165 495 1800 2025 H$_2$\001 42 4 1 0 50 -1 0 11 0.0000 2 165 465 1800 1425 T$_2$\001 43 4 1 0 50 -1 0 11 0.0000 2 165 495 2250 2025 H$_3$\001 44 4 1 0 50 -1 0 11 0.0000 2 165 465 2250 1425 T$_3$\001 -
doc/theses/mubeen_zulfiqar_MMath/figures/SharedHeaps.fig
r015925a re5d9274 1 #FIG 3.2 Produced by xfig version 3.2. 51 #FIG 3.2 Produced by xfig version 3.2.7b 2 2 Landscape 3 3 Center 4 4 Inches 5 Letter 5 Letter 6 6 100.00 7 7 Single … … 10 10 6 1500 1200 2100 1500 11 11 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 1800 1350 150 150 1800 1350 1950 1350 12 4 1 0 50 -1 0 11 0.0000 2 1 95 465 1800 1425 T$_2$\00112 4 1 0 50 -1 0 11 0.0000 2 165 465 1800 1425 T$_2$\001 13 13 -6 14 14 6 1050 1200 1650 1500 15 15 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 1350 1350 150 150 1350 1350 1500 1350 16 4 1 0 50 -1 0 11 0.0000 2 1 95 465 1350 1425 T$_1$\00116 4 1 0 50 -1 0 11 0.0000 2 165 465 1350 1425 T$_1$\001 17 17 -6 18 18 6 1950 1200 2550 1500 19 19 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 2250 1350 150 150 2250 1350 2400 1350 20 4 1 0 50 -1 0 11 0.0000 2 1 95 465 2250 1425 T$_3$\00120 4 1 0 50 -1 0 11 0.0000 2 165 465 2250 1425 T$_3$\001 21 21 -6 22 22 6 1275 1800 1875 2100 23 23 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 24 24 1425 1800 1725 1800 1725 2100 1425 2100 1425 1800 25 4 1 0 50 -1 0 11 0.0000 2 1 95 495 1575 2025 H$_1$\00125 4 1 0 50 -1 0 11 0.0000 2 165 495 1575 2025 H$_1$\001 26 26 -6 27 27 6 1725 1800 2325 2100 28 28 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 29 29 1875 1800 2175 1800 2175 2100 1875 2100 1875 1800 30 4 1 0 50 -1 0 11 0.0000 2 1 95 495 2025 2025 H$_2$\00130 4 1 0 50 -1 0 11 0.0000 2 165 495 2025 2025 H$_2$\001 31 31 -6 32 32 6 2475 1800 2775 2100 33 33 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 34 34 2475 1800 2775 1800 2775 2100 2475 2100 2475 1800 35 4 1 0 50 -1 0 11 0.0000 2 1 35135 2625 2025 G\00135 4 1 0 50 -1 0 11 0.0000 2 120 135 2625 2025 G\001 36 36 -6 37 37 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 38 0 01.00 45.00 90.0039 0 01.00 45.00 90.0038 1 1 1.00 45.00 90.00 39 1 1 1.00 45.00 90.00 40 40 1275 1500 1500 1800 41 41 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 42 0 01.00 45.00 90.0043 0 01.00 45.00 90.0042 1 1 1.00 45.00 90.00 43 1 1 1.00 45.00 90.00 44 44 1425 1500 1950 1800 45 45 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 46 0 01.00 45.00 90.0047 0 01.00 45.00 90.0046 1 1 1.00 45.00 90.00 47 1 1 1.00 45.00 90.00 48 48 1725 1500 1650 1800 49 49 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 50 0 01.00 45.00 90.0051 0 01.00 45.00 90.0050 1 1 1.00 45.00 90.00 51 1 1 1.00 45.00 90.00 52 52 1875 1500 2025 1800 53 53 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 54 0 01.00 45.00 90.0055 0 01.00 45.00 90.0054 1 1 1.00 45.00 90.00 55 1 1 1.00 45.00 90.00 56 56 2250 1500 2100 1800 57 4 0 0 50 -1 0 11 0.0000 2 1 35240 3075 2025 OS\00158 4 1 0 50 -1 0 11 0.0000 2 1 95 1320 2325 2025 $\\Leftrightarrow$\00159 4 1 0 50 -1 0 11 0.0000 2 1 95 1320 2925 2025 $\\Leftrightarrow$\00157 4 0 0 50 -1 0 11 0.0000 2 120 240 3075 2025 OS\001 58 4 1 0 50 -1 0 11 0.0000 2 180 1260 2325 2025 $\\Leftrightarrow$\001 59 4 1 0 50 -1 0 11 0.0000 2 180 1260 2925 2025 $\\Leftrightarrow$\001 -
doc/theses/mubeen_zulfiqar_MMath/figures/SingleHeap.fig
r015925a re5d9274 1 #FIG 3.2 Produced by xfig version 3.2. 51 #FIG 3.2 Produced by xfig version 3.2.7b 2 2 Landscape 3 3 Center 4 4 Inches 5 Letter 5 Letter 6 6 100.00 7 7 Single … … 10 10 6 1500 1200 2100 1500 11 11 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 1800 1350 150 150 1800 1350 1950 1350 12 4 1 0 50 -1 0 11 0.0000 2 1 95 465 1800 1425 T$_2$\00112 4 1 0 50 -1 0 11 0.0000 2 165 465 1800 1425 T$_2$\001 13 13 -6 14 14 6 1050 1200 1650 1500 15 15 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 1350 1350 150 150 1350 1350 1500 1350 16 4 1 0 50 -1 0 11 0.0000 2 1 95 465 1350 1425 T$_1$\00116 4 1 0 50 -1 0 11 0.0000 2 165 465 1350 1425 T$_1$\001 17 17 -6 18 18 6 1950 1200 2550 1500 19 19 1 3 0 1 0 7 50 -1 -1 0.000 1 0.0000 2250 1350 150 150 2250 1350 2400 1350 20 4 1 0 50 -1 0 11 0.0000 2 1 95 465 2250 1425 T$_3$\00120 4 1 0 50 -1 0 11 0.0000 2 165 465 2250 1425 T$_3$\001 21 21 -6 22 22 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 23 0 01.00 45.00 90.0024 0 01.00 45.00 90.0023 1 1 1.00 45.00 90.00 24 1 1 1.00 45.00 90.00 25 25 1350 1500 1725 1800 26 26 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 27 0 01.00 45.00 90.0028 0 01.00 45.00 90.0027 1 1 1.00 45.00 90.00 28 1 1 1.00 45.00 90.00 29 29 2250 1500 1875 1800 30 30 2 2 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 5 31 31 1650 1800 1950 1800 1950 2100 1650 2100 1650 1800 32 32 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 33 0 01.00 45.00 90.0034 0 01.00 45.00 90.0033 1 1 1.00 45.00 90.00 34 1 1 1.00 45.00 90.00 35 35 1800 1500 1800 1800 36 4 1 0 50 -1 0 11 0.0000 2 1 95 495 1800 2025 H$_1$\00137 4 1 0 50 -1 0 11 0.0000 2 1 95 1320 2100 2025 $\\Leftrightarrow$\00138 4 0 0 50 -1 0 11 0.0000 2 1 35240 2250 2025 OS\00136 4 1 0 50 -1 0 11 0.0000 2 165 495 1800 2025 H$_1$\001 37 4 1 0 50 -1 0 11 0.0000 2 180 1260 2100 2025 $\\Leftrightarrow$\001 38 4 0 0 50 -1 0 11 0.0000 2 120 240 2250 2025 OS\001 -
doc/theses/mubeen_zulfiqar_MMath/figures/UserKernelHeaps.fig
r015925a re5d9274 45 45 -6 46 46 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 47 0 01.00 45.00 90.0048 0 01.00 45.00 90.0047 1 1 1.00 45.00 90.00 48 1 1 1.00 45.00 90.00 49 49 2025 2100 2025 2400 50 50 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 51 0 01.00 45.00 90.0052 0 01.00 45.00 90.0051 1 1 1.00 45.00 90.00 52 1 1 1.00 45.00 90.00 53 53 2475 2100 2475 2400 54 54 2 1 0 1 0 7 50 -1 -1 0.000 0 0 -1 1 1 2 55 0 01.00 45.00 90.0056 0 01.00 45.00 90.0055 1 1 1.00 45.00 90.00 56 1 1 1.00 45.00 90.00 57 57 2925 2100 2925 2400 58 58 4 1 0 50 -1 0 11 0.0000 2 135 2235 2475 1725 scheduled across kernel threads\001 -
doc/theses/mubeen_zulfiqar_MMath/intro.tex
r015925a re5d9274 53 53 When this allocator proves inadequate, programmers often write specialize allocators for specific needs. 54 54 C and \CC allow easy replacement of the default memory allocator with an alternative specialized or general-purpose memory-allocator. 55 (Jikes RVM MMTk~\cite{MMTk} provides a similar generalization for the Java virtual machine.) 55 Jikes RVM MMTk~\cite{MMTk} provides a similar generalization for the Java virtual machine. 56 56 However, high-performance memory-allocators for kernel and user multi-threaded programs are still being designed and improved. 57 57 For this reason, several alternative general-purpose allocators have been written for C/\CC with the goal of scaling in a multi-threaded program~\cite{Berger00,mtmalloc,streamflow,tcmalloc}. … … 65 65 \begin{enumerate}[leftmargin=*] 66 66 \item 67 Implementation of a new stand-lone concurrent low-latency memory-allocator ($\approx$1,200 lines of code) for C/\CC programs using kernel threads (1:1 threading), and specialized versions of the allocator for the programming languages \uC and \CFA using user-level threads running over multiple kernel threads (M:N threading). 68 69 \item 70 Adopt @nullptr@ return for a zero-sized allocation, rather than an actual memory address, which can be passed to @free@. 67 Implementation of a new stand-alone concurrent low-latency memory-allocator ($\approx$1,200 lines of code) for C/\CC programs using kernel threads (1:1 threading), and specialized versions of the allocator for the programming languages \uC and \CFA using user-level threads running over multiple kernel threads (M:N threading). 71 68 72 69 \item … … 104 101 105 102 \item 106 Provide additional heap wrapper functions in \CFA creating a n orthogonalset of allocation operations and properties.103 Provide additional heap wrapper functions in \CFA creating a more usable set of allocation operations and properties. 107 104 108 105 \item … … 111 108 \item 112 109 @malloc_alignment( addr )@ returns the alignment of the allocation pointed-to by @addr@. 113 If the allocation is not aligned or @addr@ is the @ nulladdr@, the minimal alignment is returned.110 If the allocation is not aligned or @addr@ is the @NULL@, the minimal alignment is returned. 114 111 \item 115 112 @malloc_zero_fill( addr )@ returns a boolean result indicating if the memory pointed-to by @addr@ is allocated with zero fill, e.g., by @calloc@/@cmemalign@. … … 119 116 @malloc_usable_size( addr )@ returns the usable (total) size of the memory pointed-to by @addr@, i.e., the bin size containing the allocation, where @malloc_size( addr )@ $\le$ @malloc_usable_size( addr )@. 120 117 \end{itemize} 121 122 \item123 Provide mostly contention-free allocation and free operations via a heap-per-kernel-thread implementation.124 118 125 119 \item … … 136 130 137 131 \item 138 Provide extensive runtime checks to valid allocation operations and identify the amount of unfreed storage at program termination.132 Provide extensive runtime checks to validate allocation operations and identify the amount of unfreed storage at program termination. 139 133 140 134 \item -
doc/theses/mubeen_zulfiqar_MMath/performance.tex
r015925a re5d9274 3 3 4 4 This chapter uses the micro-benchmarks from \VRef[Chapter]{s:Benchmarks} to test a number of current memory allocators, including llheap. 5 The goal is to see if llheap is competitive with the current bestmemory allocators.5 The goal is to see if llheap is competitive with the currently popular memory allocators. 6 6 7 7 … … 11 11 \begin{itemize} 12 12 \item 13 \textbf{Algol} Huawei ARM TaiShan 2280 V2 Kunpeng 920, 24-core socket $\times$ 4, 2.6 GHz, GCC version 9.4.0 14 \item 13 15 \textbf{Nasus} AMD EPYC 7662, 64-core socket $\times$ 2, 2.0 GHz, GCC version 9.3.0 14 \item15 \textbf{Algol} Huawei ARM TaiShan 2280 V2 Kunpeng 920, 24-core socket $\times$ 4, 2.6 GHz, GCC version 9.4.016 16 \end{itemize} 17 17 … … 31 31 32 32 \paragraph{glibc (\textsf{glc})} 33 \cite{glibc} is the default g cc thread-safe allocator.33 \cite{glibc} is the default glibc thread-safe allocator. 34 34 \\ 35 35 \textbf{Version:} Ubuntu GLIBC 2.31-0ubuntu9.7 2.31\\ … … 46 46 47 47 \paragraph{hoard (\textsf{hrd})} 48 \cite{hoard} is a thread-safe allocator that is multi-threaded and us inga heap layer framework. It has per-thread heaps that have thread-local free-lists, and a global shared heap.48 \cite{hoard} is a thread-safe allocator that is multi-threaded and uses a heap layer framework. It has per-thread heaps that have thread-local free-lists, and a global shared heap. 49 49 \\ 50 50 \textbf{Version:} 3.13\\ … … 78 78 79 79 \paragraph{tbb malloc (\textsf{tbb})} 80 \cite{tbbmalloc} is a thread-safe allocator that is multi-threaded and uses private heap for each thread.80 \cite{tbbmalloc} is a thread-safe allocator that is multi-threaded and uses a private heap for each thread. 81 81 Each private-heap has multiple bins of different sizes. Each bin contains free regions of the same size. 82 82 \\ … … 90 90 \section{Experiments} 91 91 92 The each micro-benchmark is configured and run with each of the allocators,93 The less time an allocator takes to complete a benchmark the better , so lower in the graphs is better.92 Each micro-benchmark is configured and run with each of the allocators, 93 The less time an allocator takes to complete a benchmark the better so lower in the graphs is better, except for the Memory micro-benchmark graphs. 94 94 All graphs use log scale on the Y-axis, except for the Memory micro-benchmark (see \VRef{s:MemoryMicroBenchmark}). 95 95 … … 231 231 Second is the low-performer group, which includes the rest of the memory allocators. 232 232 These memory allocators have significant program-induced passive false-sharing, where \textsf{hrd}'s is the worst performing allocator. 233 All of the allocator's in this group are sharing heaps among threads at some level. 234 235 Interestingly, allocators such as \textsf{hrd} and \textsf{glc} performed well in micro-benchmark cache thrash (see \VRef{sec:cache-thrash-perf}). 236 But, these allocators are among the low performers in the cache scratch. 237 It suggests these allocators do not actively produce false-sharing but preserve program-induced passive false sharing. 233 All of the allocators in this group are sharing heaps among threads at some level. 234 235 Interestingly, allocators such as \textsf{hrd} and \textsf{glc} performed well in micro-benchmark cache thrash (see \VRef{sec:cache-thrash-perf}), but, these allocators are among the low performers in the cache scratch. 236 It suggests these allocators do not actively produce false-sharing, but preserve program-induced passive false sharing. 238 237 239 238 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -
doc/theses/mubeen_zulfiqar_MMath/uw-ethesis-frontpgs.tex
r015925a re5d9274 13 13 \vspace*{1.0cm} 14 14 15 {\Huge\bf \CFAMemory Allocation}15 {\Huge\bf High-Performance Concurrent Memory Allocation} 16 16 17 17 \vspace*{1.0cm} … … 108 108 % D E C L A R A T I O N P A G E 109 109 % ------------------------------- 110 % The following is a sample De laration Page as provided by the GSO110 % The following is a sample Declaration Page as provided by the GSO 111 111 % December 13th, 2006. It is designed for an electronic thesis. 112 112 \begin{center}\textbf{Author's Declaration}\end{center} … … 136 136 137 137 The goal of this thesis is to build a low-latency memory allocator for both kernel and user multi-threaded systems, which is competitive with the best current memory allocators, while extending the feature set of existing and new allocator routines. 138 A new llheap memory-allocator is created that achieves all of these goals, while maintaining and managing sticky allocation properties for zero-fill and alignmentallocations without a performance loss.138 A new llheap memory-allocator is created that achieves all of these goals, while maintaining and managing sticky allocation properties for zero-filled and aligned allocations without a performance loss. 139 139 Hence, it becomes possible to use @realloc@ frequently as a safe operation, rather than just occasionally, because it preserves sticky properties when enlarging storage requests. 140 140 Furthermore, the ability to query sticky properties and information allows programmers to write safer programs, as it is possible to dynamically match allocation styles from unknown library routines that return allocations. 141 141 The C allocation API is also extended with @resize@, advanced @realloc@, @aalloc@, @amemalign@, and @cmemalign@ so programmers do not make mistakes writing theses useful allocation operations. 142 142 llheap is embedded into the \uC and \CFA runtime systems, both of which have user-level threading. 143 The ability to use \CFA's advanced type-system (and possibly \CC's too) to have one allocation routine with completely orthogonal sticky properties shows how far the allocation API can be pushed, which increases safety and greatly simplifies programmer's use of dynamic allocation.143 The ability to use \CFA's advanced type-system (and possibly \CC's too) to combine advanced memory operations into one allocation routine using named arguments shows how far the allocation API can be pushed, which increases safety and greatly simplifies programmer's use of dynamic allocation. 144 144 145 145 The llheap allocator also provides comprehensive statistics for all allocation operations, which are invaluable in understanding and debugging a program's dynamic behaviour. 146 No other memory allocator examined in the thesis provides comprehensive statistics gathering.147 As well, llheap provides a debugging mode where allocations are checked , along with internal pre/post conditions and invariants,is extremely useful, especially for students.146 No other memory allocator examined in the thesis provides such comprehensive statistics gathering. 147 As well, llheap provides a debugging mode where allocations are checked with internal pre/post conditions and invariants. It is extremely useful, especially for students. 148 148 While not as powerful as the @valgrind@ interpreter, a large number of allocations mistakes are detected. 149 149 Finally, contention-free statistics gathering and debugging have a low enough cost to be used in production code. 150 150 151 A micro-benchmark test-suite is started for comparing allocators, rather than relying on a suite of arbitrary programs ,has been an interesting challenge.151 A micro-benchmark test-suite is started for comparing allocators, rather than relying on a suite of arbitrary programs. It has been an interesting challenge. 152 152 These micro-benchmarks have adjustment knobs to simulate allocation patterns hard-coded into arbitrary test programs. 153 Existing memory allocators, glibc, dlmalloc, hoard, jemalloc, ptmalloc3, rpmalloc, tbmalloc and the new allocator llheap are all compared using the new micro-benchmark test-suite.153 Existing memory allocators, glibc, dlmalloc, hoard, jemalloc, ptmalloc3, rpmalloc, tbmalloc, and the new allocator llheap are all compared using the new micro-benchmark test-suite. 154 154 \cleardoublepage 155 155 … … 162 162 I would like to thank all the people who made this thesis possible. 163 163 164 I would like to acknowledge Peter A. Buhr for his assistance and support through tout the process.164 I would like to acknowledge Peter A. Buhr for his assistance and support throughout the process. 165 165 It would have been impossible without him. 166 166 167 I would like to acknowledge Gregor Richards and Trevor Brown for reading my thesis quickly and giving me great feedback on my work. 168 167 169 Also, I would say thanks to my team members at PLG especially Thierry, Michael, and Andrew for their input. 170 171 Finally, a special thank you to Huawei Canada for funding this work. 168 172 \end{center} 169 173 \cleardoublepage … … 195 199 % L I S T O F T A B L E S 196 200 % --------------------------- 197 \addcontentsline{toc}{chapter}{List of Tables}198 \listoftables199 \cleardoublepage200 \phantomsection % allows hyperref to link to the correct page201 % \addcontentsline{toc}{chapter}{List of Tables} 202 % \listoftables 203 % \cleardoublepage 204 % \phantomsection % allows hyperref to link to the correct page 201 205 202 206 % Change page numbering back to Arabic numerals -
doc/theses/mubeen_zulfiqar_MMath/uw-ethesis.tex
r015925a re5d9274 106 106 pdffitwindow=false, % window fit to page when opened 107 107 pdfstartview={FitH}, % fits the width of the page to the window 108 pdftitle={ CforallMemory Allocation}, % title: CHANGE THIS TEXT!108 pdftitle={High-Performance Concurrent Memory Allocation}, % title: CHANGE THIS TEXT! 109 109 pdfauthor={Mubeen Zulfiqar}, % author: CHANGE THIS TEXT! and uncomment this line 110 110 pdfsubject={Cforall}, % subject: CHANGE THIS TEXT! and uncomment this line -
doc/theses/thierry_delisle_PhD/thesis/Makefile
r015925a re5d9274 3 3 Build = build 4 4 Figures = img 5 Macros = ../../../LaTeXmacros 6 TeXLIB = .:${Macros}:${Build}:../../../bibliography: 5 6 LaTMac = ../../../LaTeXmacros 7 BibRep = ../../../bibliography 8 9 Macros = ${LaTMac} 10 TeXLIB = .:${Macros}:${Build}:${BibRep}: 7 11 LaTeX = TEXINPUTS=${TeXLIB} && export TEXINPUTS && latex -halt-on-error -output-directory=${Build} 8 12 BibTeX = BIBINPUTS=${TeXLIB} && export BIBINPUTS && bibtex … … 37 41 emptytree \ 38 42 fairness \ 43 idle \ 44 idle1 \ 45 idle2 \ 46 idle_state \ 39 47 io_uring \ 40 48 pivot_ring \ … … 42 50 cycle \ 43 51 result.cycle.jax.ops \ 52 result.yield.jax.ops \ 53 result.churn.jax.ops \ 54 result.cycle.jax.ns \ 55 result.yield.jax.ns \ 56 result.churn.jax.ns \ 57 result.cycle.low.jax.ops \ 58 result.yield.low.jax.ops \ 59 result.churn.low.jax.ops \ 60 result.cycle.low.jax.ns \ 61 result.yield.low.jax.ns \ 62 result.churn.low.jax.ns \ 63 result.memcd.updt.qps \ 64 result.memcd.updt.lat \ 65 result.memcd.rate.qps \ 66 result.memcd.rate.99th \ 44 67 } 45 68 … … 52 75 ## Define the documents that need to be made. 53 76 all: thesis.pdf 54 thesis.pdf: ${TEXTS} ${FIGURES} ${PICTURES} thesis.tex glossary.tex local.bib ../../../LaTeXmacros/common.tex ../../../LaTeXmacros/common.sty77 thesis.pdf: ${TEXTS} ${FIGURES} ${PICTURES} thesis.tex glossary.tex local.bib ${LaTMac}/common.tex ${LaTMac}/common.sty ${BibRep}/pl.bib 55 78 56 79 DOCUMENT = thesis.pdf … … 116 139 python3 $< $@ 117 140 118 build/result.%.ns.svg : data/% | ${Build} 119 ../../../../benchmark/plot.py -f $< -o $@ -y "ns per ops" 141 cycle_jax_ops_FLAGS = --MaxY=120000000 142 cycle_low_jax_ops_FLAGS = --MaxY=120000000 143 cycle_jax_ns_FLAGS = --MaxY=2000 144 cycle_low_jax_ns_FLAGS = --MaxY=2000 120 145 121 build/result.%.ops.svg : data/% | ${Build} 122 ../../../../benchmark/plot.py -f $< -o $@ -y "Ops per second" 146 yield_jax_ops_FLAGS = --MaxY=150000000 147 yield_low_jax_ops_FLAGS = --MaxY=150000000 148 yield_jax_ns_FLAGS = --MaxY=1500 149 yield_low_jax_ns_FLAGS = --MaxY=1500 150 151 build/result.%.ns.svg : data/% Makefile | ${Build} 152 ../../../../benchmark/plot.py -f $< -o $@ -y "ns per ops/procs" $($(subst .,_,$*)_ns_FLAGS) 153 154 build/result.%.ops.svg : data/% Makefile | ${Build} 155 ../../../../benchmark/plot.py -f $< -o $@ -y "Ops per second" $($(subst .,_,$*)_ops_FLAGS) 156 157 build/result.memcd.updt.qps.svg : data/memcd.updt Makefile | ${Build} 158 ../../../../benchmark/plot.py -f $< -o $@ -y "Actual QPS" -x "Update Ratio" 159 160 build/result.memcd.updt.lat.svg : data/memcd.updt Makefile | ${Build} 161 ../../../../benchmark/plot.py -f $< -o $@ -y "Average Read Latency" -x "Update Ratio" 162 163 build/result.memcd.rate.qps.svg : data/memcd.rate Makefile | ${Build} 164 ../../../../benchmark/plot.py -f $< -o $@ -y "Actual QPS" -x "Target QPS" 165 166 build/result.memcd.rate.99th.svg : data/memcd.rate Makefile | ${Build} 167 ../../../../benchmark/plot.py -f $< -o $@ -y "Tail Read Latency" -x "Target QPS" 123 168 124 169 ## pstex with inverted colors -
doc/theses/thierry_delisle_PhD/thesis/data/cycle.jax
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5619274.9, "ns per ops/procs": 177.96}]]1 [["rdq-cycle-go", "./rdq-cycle-go -p 24 -d 10 -r 5 -t 2400", {"Duration (ms)": 10001.0, "Number of processors": 24.0, "Number of threads": 12000.0, "Cycle size (# thrds)": 5.0, "Total Operations(ops)": 1138076440.0, "Ops per second": 113792094.48, "ns per ops": 8.79, "Ops per threads": 94839.0, "Ops per procs": 47419851.0, "Ops/sec/procs": 4741337.27, "ns per ops/procs": 210.91}],["rdq-cycle-go", "./rdq-cycle-go -p 16 -d 10 -r 5 -t 1600", {"Duration (ms)": 200285.0, "Number of processors": 16.0, "Number of threads": 8000.0, "Cycle size (# thrds)": 5.0, "Total Operations(ops)": 17638575791.0, "Ops per second": 88067238.72, "ns per ops": 11.35, "Ops per threads": 2204821.0, "Ops per procs": 1102410986.0, "Ops/sec/procs": 5504202.42, "ns per ops/procs": 181.68}],["rdq-cycle-tokio", "./rdq-cycle-tokio -p 1 -d 10 -r 5 -t 100", {"Duration (ms)": 10100.0, "Number of processors": 1.0, "Number of threads": 500.0, "Cycle size (# thrds)": 5.0, "Total 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doc/theses/thierry_delisle_PhD/thesis/local.bib
r015925a re5d9274 701 701 note = "[Online; accessed 12-April-2022]" 702 702 } 703 704 % RMR notes : 705 % [05/04, 12:36] Trevor Brown 706 % i don't know where rmr complexity was first introduced, but there are many many many papers that use the term and define it 707 % [05/04, 12:37] Trevor Brown 708 % here's one paper that uses the term a lot and links to many others that use it... might trace it to something useful there https://drops.dagstuhl.de/opus/volltexte/2021/14832/pdf/LIPIcs-DISC-2021-30.pdf 709 % [05/04, 12:37] Trevor Brown 710 % another option might be to cite a textbook 711 % [05/04, 12:42] Trevor Brown 712 % but i checked two textbooks in the area i'm aware of and i don't see a definition of rmr complexity in either 713 % [05/04, 12:42] Trevor Brown 714 % this one has a nice statement about the prevelance of rmr complexity, as well as some rough definition 715 % [05/04, 12:42] Trevor Brown 716 % https://dl.acm.org/doi/pdf/10.1145/3465084.3467938 717 718 % Race to idle notes : 719 % [13/04, 16:56] Martin Karsten 720 % I don't have a citation. Google brings up this one, which might be good: 721 % 722 % https://doi.org/10.1137/1.9781611973099.100 -
doc/theses/thierry_delisle_PhD/thesis/text/eval_macro.tex
r015925a re5d9274 7 7 Networked ZIPF 8 8 9 Nginx : 5Gb still good, 4Gb starts to suffer 10 11 Cforall : 10Gb too high, 4 Gb too low 12 9 13 \section{Memcached} 10 14 11 In Memory 15 \subsection{Benchmark Environment} 16 These experiments are run on a cluster of homogenous Supermicro SYS-6017R-TDF compute nodes with the following characteristics: 17 The server runs Ubuntu 20.04.3 LTS on top of Linux Kernel 5.11.0-34. 18 Each node has 2 Intel(R) Xeon(R) CPU E5-2620 v2 running at 2.10GHz. 19 These CPUs have 6 cores per CPUs and 2 \glspl{hthrd} per core, for a total of 24 \glspl{hthrd}. 20 The cpus each have 384 KB, 3 MB and 30 MB of L1, L2 and L3 caches respectively. 21 Each node is connected to the network through a Mellanox 10 Gigabit Ethernet port. 22 The network route uses 1 Mellanox SX1012 10/40 Gigabit Ethernet cluster switch. 12 23 13 Networked 24 25 26 \begin{figure} 27 \centering 28 \input{result.memcd.updt.qps.pstex_t} 29 \caption[Churn Benchmark : Throughput on Intel]{Churn Benchmark : Throughput on Intel\smallskip\newline Description} 30 \label{fig:memcd:updt:qps} 31 \end{figure} 32 33 \begin{figure} 34 \centering 35 \input{result.memcd.updt.lat.pstex_t} 36 \caption[Churn Benchmark : Throughput on Intel]{Churn Benchmark : Throughput on Intel\smallskip\newline Description} 37 \label{fig:memcd:updt:lat} 38 \end{figure} 39 40 \begin{figure} 41 \centering 42 \input{result.memcd.rate.qps.pstex_t} 43 \caption[Churn Benchmark : Throughput on Intel]{Churn Benchmark : Throughput on Intel\smallskip\newline Description} 44 \label{fig:memcd:rate:qps} 45 \end{figure} 46 47 \begin{figure} 48 \centering 49 \input{result.memcd.rate.99th.pstex_t} 50 \caption[Churn Benchmark : Throughput on Intel]{Churn Benchmark : Throughput on Intel\smallskip\newline Description} 51 \label{fig:memcd:rate:tail} 52 \end{figure} -
doc/theses/thierry_delisle_PhD/thesis/text/eval_micro.tex
r015925a re5d9274 6 6 \section{Benchmark Environment} 7 7 All of these benchmarks are run on two distinct hardware environment, an AMD and an INTEL machine. 8 9 For all benchmarks, \texttt{taskset} is used to limit the experiment to 1 NUMA Node with no hyper threading. 10 If more \glspl{hthrd} are needed, then 1 NUMA Node with hyperthreading is used. 11 If still more \glspl{hthrd} are needed then the experiment is limited to as few NUMA Nodes as needed. 12 8 13 9 14 \paragraph{AMD} The AMD machine is a server with two AMD EPYC 7662 CPUs and 256GB of DDR4 RAM. … … 23 28 24 29 \section{Cycling latency} 30 \begin{figure} 31 \centering 32 \input{cycle.pstex_t} 33 \caption[Cycle benchmark]{Cycle benchmark\smallskip\newline Each \gls{at} unparks the next \gls{at} in the cycle before parking itself.} 34 \label{fig:cycle} 35 \end{figure} 25 36 The most basic evaluation of any ready queue is to evaluate the latency needed to push and pop one element from the ready-queue. 26 37 Since these two operation also describe a \texttt{yield} operation, many systems use this as the most basic benchmark. … … 42 53 Note that this problem is only present on SMP machines and is significantly mitigated by the fact that there are multiple rings in the system. 43 54 44 \begin{figure}45 \centering46 \input{cycle.pstex_t}47 \caption[Cycle benchmark]{Cycle benchmark\smallskip\newline Each \gls{at} unparks the next \gls{at} in the cycle before parking itself.}48 \label{fig:cycle}49 \end{figure}50 51 55 To avoid this benchmark from being dominated by the idle sleep handling, the number of rings is kept at least as high as the number of \glspl{proc} available. 52 56 Beyond this point, adding more rings serves to mitigate even more the idle sleep handling. … … 54 58 55 59 The actual benchmark is more complicated to handle termination, but that simply requires using a binary semphore or a channel instead of raw \texttt{park}/\texttt{unpark} and carefully picking the order of the \texttt{P} and \texttt{V} with respect to the loop condition. 56 57 \begin{lstlisting} 58 Thread.main() { 59 count := 0 60 for { 61 wait() 62 this.next.wake() 63 count ++ 64 if must_stop() { break } 65 } 66 global.count += count 67 } 68 \end{lstlisting} 69 70 \begin{figure} 71 \centering 72 \input{result.cycle.jax.ops.pstex_t} 73 \vspace*{-10pt} 74 \label{fig:cycle:ns:jax} 75 \end{figure} 60 Figure~\ref{fig:cycle:code} shows pseudo code for this benchmark. 61 62 \begin{figure} 63 \begin{lstlisting} 64 Thread.main() { 65 count := 0 66 for { 67 wait() 68 this.next.wake() 69 count ++ 70 if must_stop() { break } 71 } 72 global.count += count 73 } 74 \end{lstlisting} 75 \caption[Cycle Benchmark : Pseudo Code]{Cycle Benchmark : Pseudo Code} 76 \label{fig:cycle:code} 77 \end{figure} 78 79 80 81 \subsection{Results} 82 \begin{figure} 83 \subfloat[][Throughput, 100 \ats per \proc]{ 84 \resizebox{0.5\linewidth}{!}{ 85 \input{result.cycle.jax.ops.pstex_t} 86 } 87 \label{fig:cycle:jax:ops} 88 } 89 \subfloat[][Throughput, 1 \ats per \proc]{ 90 \resizebox{0.5\linewidth}{!}{ 91 \input{result.cycle.low.jax.ops.pstex_t} 92 } 93 \label{fig:cycle:jax:low:ops} 94 } 95 96 \subfloat[][Latency, 100 \ats per \proc]{ 97 \resizebox{0.5\linewidth}{!}{ 98 \input{result.cycle.jax.ns.pstex_t} 99 } 100 101 } 102 \subfloat[][Latency, 1 \ats per \proc]{ 103 \resizebox{0.5\linewidth}{!}{ 104 \input{result.cycle.low.jax.ns.pstex_t} 105 } 106 \label{fig:cycle:jax:low:ns} 107 } 108 \caption[Cycle Benchmark on Intel]{Cycle Benchmark on Intel\smallskip\newline Throughput as a function of \proc count, using 100 cycles per \proc, 5 \ats per cycle.} 109 \label{fig:cycle:jax} 110 \end{figure} 111 Figure~\ref{fig:cycle:jax} shows the throughput as a function of \proc count, with the following constants: 112 Each run uses 100 cycles per \proc, 5 \ats per cycle. 113 114 \todo{results discussion} 76 115 77 116 \section{Yield} … … 81 120 Its only interesting variable is the number of \glspl{at} per \glspl{proc}, where ratios close to 1 means the ready queue(s) could be empty. 82 121 This sometimes puts more strain on the idle sleep handling, compared to scenarios where there is clearly plenty of work to be done. 83 84 \todo{code, setup, results} 85 86 \begin{lstlisting} 87 Thread.main() { 88 count := 0 89 while !stop { 90 yield() 91 count ++ 92 } 93 global.count += count 94 } 95 \end{lstlisting} 122 Figure~\ref{fig:yield:code} shows pseudo code for this benchmark, the ``wait/wake-next'' is simply replaced by a yield. 123 124 \begin{figure} 125 \begin{lstlisting} 126 Thread.main() { 127 count := 0 128 for { 129 yield() 130 count ++ 131 if must_stop() { break } 132 } 133 global.count += count 134 } 135 \end{lstlisting} 136 \caption[Yield Benchmark : Pseudo Code]{Yield Benchmark : Pseudo Code} 137 \label{fig:yield:code} 138 \end{figure} 139 140 \subsection{Results} 141 \begin{figure} 142 \subfloat[][Throughput, 100 \ats per \proc]{ 143 \resizebox{0.5\linewidth}{!}{ 144 \input{result.yield.jax.ops.pstex_t} 145 } 146 \label{fig:yield:jax:ops} 147 } 148 \subfloat[][Throughput, 1 \ats per \proc]{ 149 \resizebox{0.5\linewidth}{!}{ 150 \input{result.yield.low.jax.ops.pstex_t} 151 } 152 \label{fig:yield:jax:low:ops} 153 } 154 155 \subfloat[][Latency, 100 \ats per \proc]{ 156 \resizebox{0.5\linewidth}{!}{ 157 \input{result.yield.jax.ns.pstex_t} 158 } 159 \label{fig:yield:jax:ns} 160 } 161 \subfloat[][Latency, 1 \ats per \proc]{ 162 \resizebox{0.5\linewidth}{!}{ 163 \input{result.yield.low.jax.ns.pstex_t} 164 } 165 \label{fig:yield:jax:low:ns} 166 } 167 \caption[Yield Benchmark on Intel]{Yield Benchmark on Intel\smallskip\newline Throughput as a function of \proc count, using 1 \ats per \proc.} 168 \label{fig:yield:jax} 169 \end{figure} 170 Figure~\ref{fig:yield:ops:jax} shows the throughput as a function of \proc count, with the following constants: 171 Each run uses 100 \ats per \proc. 172 173 \todo{results discussion} 96 174 97 175 … … 105 183 In either case, this benchmark aims to highlight how each scheduler handles these cases, since both cases can lead to performance degradation if they are not handled correctly. 106 184 107 To achieve this the benchmark uses a fixed size array of \newterm{chair}s, where a chair is a data structure that holds a single blocked \gls{at}. 108 When a \gls{at} attempts to block on the chair, it must first unblocked the \gls{at} currently blocked on said chair, if any. 109 This creates a flow where \glspl{at} push each other out of the chairs before being pushed out themselves. 110 For this benchmark to work however, the number of \glspl{at} must be equal or greater to the number of chairs plus the number of \glspl{proc}. 185 To achieve this the benchmark uses a fixed size array of semaphores. 186 Each \gls{at} picks a random semaphore, \texttt{V}s it to unblock a \at waiting and then \texttt{P}s on the semaphore. 187 This creates a flow where \glspl{at} push each other out of the semaphores before being pushed out themselves. 188 For this benchmark to work however, the number of \glspl{at} must be equal or greater to the number of semaphores plus the number of \glspl{proc}. 189 Note that the nature of these semaphores mean the counter can go beyond 1, which could lead to calls to \texttt{P} not blocking. 111 190 112 191 \todo{code, setup, results} … … 116 195 for { 117 196 r := random() % len(spots) 118 next := xchg(spots[r], this) 119 if next { next.wake() } 120 wait() 197 spots[r].V() 198 spots[r].P() 121 199 count ++ 122 200 if must_stop() { break } … … 125 203 } 126 204 \end{lstlisting} 205 206 \begin{figure} 207 \subfloat[][Throughput, 100 \ats per \proc]{ 208 \resizebox{0.5\linewidth}{!}{ 209 \input{result.churn.jax.ops.pstex_t} 210 } 211 \label{fig:churn:jax:ops} 212 } 213 \subfloat[][Throughput, 1 \ats per \proc]{ 214 \resizebox{0.5\linewidth}{!}{ 215 \input{result.churn.low.jax.ops.pstex_t} 216 } 217 \label{fig:churn:jax:low:ops} 218 } 219 220 \subfloat[][Latency, 100 \ats per \proc]{ 221 \resizebox{0.5\linewidth}{!}{ 222 \input{result.churn.jax.ns.pstex_t} 223 } 224 225 } 226 \subfloat[][Latency, 1 \ats per \proc]{ 227 \resizebox{0.5\linewidth}{!}{ 228 \input{result.churn.low.jax.ns.pstex_t} 229 } 230 \label{fig:churn:jax:low:ns} 231 } 232 \caption[Churn Benchmark on Intel]{\centering Churn Benchmark on Intel\smallskip\newline Throughput and latency of the Churn on the benchmark on the Intel machine. Throughput is the total operation per second across all cores. Latency is the duration of each opeartion.} 233 \label{fig:churn:jax} 234 \end{figure} 127 235 128 236 \section{Locality} -
doc/theses/thierry_delisle_PhD/thesis/text/intro.tex
r015925a re5d9274 2 2 \todo{A proper intro} 3 3 4 The C programming language \cit{C}4 The C programming language~\cite{C11} 5 5 6 The \CFA programming language\cite{cfa:frontpage,cfa:typesystem} which extends the C programming language to add modern safety and productiviy features while maintaining backwards compatibility. Among it's productiviy features, \CFA introduces support for threading\cit{CFA Concurrency}, to allow programmers to write modern concurrent and parallel programming. 7 While previous work on the concurrent package of \CFA focused on features and interfaces, this thesis focuses on performance, introducing \glsxtrshort{api} changes only when required by performance considerations. More specifically, this thesis concentrates on scheduling and \glsxtrshort{io}. Prior to this work, the \CFA runtime used a strictly \glsxtrshort{fifo} \gls{rQ}. 6 The \CFA programming language~\cite{cfa:frontpage,cfa:typesystem} extends the C programming language by adding modern safety and productivity features, while maintaining backwards compatibility. Among its productivity features, \CFA supports user-level threading~\cite{Delisle21} allowing programmers to write modern concurrent and parallel programs. 7 My previous master's thesis on concurrent in \CFA focused on features and interfaces. 8 This Ph.D.\ thesis focuses on performance, introducing \glsxtrshort{api} changes only when required by performance considerations. Specifically, this work concentrates on scheduling and \glsxtrshort{io}. Prior to this work, the \CFA runtime used a strict \glsxtrshort{fifo} \gls{rQ} and no non-blocking I/O capabilities at the user-thread level. 8 9 9 This work exclusively concentrates on Linux as it's operating system since the existing \CFA runtime and compiler does not already support other operating systems. Furthermore, as \CFA is yet to be released, supporting version of Linux older than the latest versionis not a goal of this work.10 As a research project, this work builds exclusively on newer versions of the Linux operating-system and gcc/clang compilers. While \CFA is released, supporting older versions of Linux ($<$~Ubuntu 16.04) and gcc/clang compilers ($<$~gcc 6.0) is not a goal of this work. -
doc/theses/thierry_delisle_PhD/thesis/text/practice.tex
r015925a re5d9274 7 7 More precise \CFA supports adding \procs using the RAII object @processor@. 8 8 These objects can be created at any time and can be destroyed at any time. 9 They are normally create as automatic stack variables, but this is not a requirement.9 They are normally created as automatic stack variables, but this is not a requirement. 10 10 11 11 The consequence is that the scheduler and \io subsystems must support \procs comming in and out of existence. 12 12 13 13 \section{Manual Resizing} 14 The consequence of dynamically changing the number of \procs is that all internal arrays that are sized based on the number of \procs neede to be \texttt{realloc}ed. 15 This also means that any references into these arrays, pointers or indexes, may need to be fixed when shrinking\footnote{Indexes may still need fixing because there is no guarantee the \proc causing the shrink had the highest index. Therefore indexes need to be reassigned to preserve contiguous indexes.}. 16 17 There are no performance requirements, within reason, for resizing since this is usually considered as part of setup and teardown. 14 Manual resizing is expected to be a rare operation. 15 Programmers are mostly expected to resize clusters on startup or teardown. 16 Therefore dynamically changing the number of \procs is an appropriate moment to allocate or free resources to match the new state. 17 As such all internal arrays that are sized based on the number of \procs need to be \texttt{realloc}ed. 18 This also means that any references into these arrays, pointers or indexes, may need to be fixed when shrinking\footnote{Indexes may still need fixing when shrinkingbecause some indexes are expected to refer to dense contiguous resources and there is no guarantee the resource being removed has the highest index.}. 19 20 There are no performance requirements, within reason, for resizing since it is expected to be rare. 18 21 However, this operation has strict correctness requirements since shrinking and idle sleep can easily lead to deadlocks. 19 22 It should also avoid as much as possible any effect on performance when the number of \procs remain constant. 20 This later requirement pr ehibits simple solutions, like simply adding a global lock to these arrays.23 This later requirement prohibits naive solutions, like simply adding a global lock to the ready-queue arrays. 21 24 22 25 \subsection{Read-Copy-Update} … … 24 27 In this pattern, resizing is done by creating a copy of the internal data strucures, updating the copy with the desired changes, and then attempt an Idiana Jones Switch to replace the original witht the copy. 25 28 This approach potentially has the advantage that it may not need any synchronization to do the switch. 26 The switch definitely implies a race where \procs could still use the previous, original, data structure after the copy was switched in.27 Th e important question then becomes whether or not this race can be recovered from.28 If the changes that arrived late can be transferred from the original to the copy then this solution works. 29 30 For linked-lists, dequeing is somewhat of a problem.29 However, there is a race where \procs could still use the previous, original, data structure after the copy was switched in. 30 This race not only requires some added memory reclamation scheme, it also requires that operations made on the stale original version be eventually moved to the copy. 31 32 For linked-lists, enqueing is only somewhat problematic, \ats enqueued to the original queues need to be transferred to the new, which might not preserve ordering. 33 Dequeing is more challenging. 31 34 Dequeing from the original will not necessarily update the copy which could lead to multiple \procs dequeing the same \at. 32 Fixing this requires m aking the array contain pointers to subqueues rather than the subqueues themselves.35 Fixing this requires more synchronization or more indirection on the queues. 33 36 34 37 Another challenge is that the original must be kept until all \procs have witnessed the change. … … 97 100 In addition to users manually changing the number of \procs, it is desireable to support ``removing'' \procs when there is not enough \ats for all the \procs to be useful. 98 101 While manual resizing is expected to be rare, the number of \ats is expected to vary much more which means \procs may need to be ``removed'' for only short periods of time. 99 Furthermore, race conditions that spuriously lead to the impression no \ats are ready are actually common in practice.100 Therefore \procs should not be actually \emph{removed} butsimply put into an idle state where the \gls{kthrd} is blocked until more \ats become ready.102 Furthermore, race conditions that spuriously lead to the impression that no \ats are ready are actually common in practice. 103 Therefore resources associated with \procs should not be freed but \procs simply put into an idle state where the \gls{kthrd} is blocked until more \ats become ready. 101 104 This state is referred to as \newterm{Idle-Sleep}. 102 105 … … 110 113 The \CFA scheduler simply follows the ``Race-to-Idle'\cit{https://doi.org/10.1137/1.9781611973099.100}' approach where a sleeping \proc is woken any time an \at becomes ready and \procs go to idle sleep anytime they run out of work. 111 114 115 \section{Sleeping} 116 As usual, the corner-stone of any feature related to the kernel is the choice of system call. 117 In terms of blocking a \gls{kthrd} until some event occurs the linux kernel has many available options: 118 119 \paragraph{\texttt{pthread\_mutex}/\texttt{pthread\_cond}} 120 The most classic option is to use some combination of \texttt{pthread\_mutex} and \texttt{pthread\_cond}. 121 These serve as straight forward mutual exclusion and synchronization tools and allow a \gls{kthrd} to wait on a \texttt{pthread\_cond} until signalled. 122 While this approach is generally perfectly appropriate for \glspl{kthrd} waiting after eachother, \io operations do not signal \texttt{pthread\_cond}s. 123 For \io results to wake a \proc waiting on a \texttt{pthread\_cond} means that a different \glspl{kthrd} must be woken up first, and then the \proc can be signalled. 124 125 \subsection{\texttt{io\_uring} and Epoll} 126 An alternative is to flip the problem on its head and block waiting for \io, using \texttt{io\_uring} or even \texttt{epoll}. 127 This creates the inverse situation, where \io operations directly wake sleeping \procs but waking \proc from a running \gls{kthrd} must use an indirect scheme. 128 This generally takes the form of creating a file descriptor, \eg, a dummy file, a pipe or an event fd, and using that file descriptor when \procs need to wake eachother. 129 This leads to additional complexity because there can be a race between these artificial \io operations and genuine \io operations. 130 If not handled correctly, this can lead to the artificial files going out of sync. 131 132 \subsection{Event FDs} 133 Another interesting approach is to use an event file descriptor\cit{eventfd}. 134 This is a Linux feature that is a file descriptor that behaves like \io, \ie, uses \texttt{read} and \texttt{write}, but also behaves like a semaphore. 135 Indeed, all read and writes must use 64bits large values\footnote{On 64-bit Linux, a 32-bit Linux would use 32 bits values.}. 136 Writes add their values to the buffer, that is arithmetic addition and not buffer append, and reads zero out the buffer and return the buffer values so far\footnote{This is without the \texttt{EFD\_SEMAPHORE} flag. This flags changes the behavior of \texttt{read} but is not needed for this work.}. 137 If a read is made while the buffer is already 0, the read blocks until a non-0 value is added. 138 What makes this feature particularly interesting is that \texttt{io\_uring} supports the \texttt{IORING\_REGISTER\_EVENTFD} command, to register an event fd to a particular instance. 139 Once that instance is registered, any \io completion will result in \texttt{io\_uring} writing to the event FD. 140 This means that a \proc waiting on the event FD can be \emph{directly} woken up by either other \procs or incomming \io. 141 142 \begin{figure} 143 \centering 144 \input{idle1.pstex_t} 145 \caption[Basic Idle Sleep Data Structure]{Basic Idle Sleep Data Structure \smallskip\newline Each idle \proc is put unto a doubly-linked stack protected by a lock. 146 Each \proc has a private event FD.} 147 \label{fig:idle1} 148 \end{figure} 149 112 150 113 151 \section{Tracking Sleepers} 114 152 Tracking which \procs are in idle sleep requires a data structure holding all the sleeping \procs, but more importantly it requires a concurrent \emph{handshake} so that no \at is stranded on a ready-queue with no active \proc. 115 153 The classic challenge is when a \at is made ready while a \proc is going to sleep, there is a race where the new \at may not see the sleeping \proc and the sleeping \proc may not see the ready \at. 116 117 Furthermore, the ``Race-to-Idle'' approach means that there is some 118 119 \section{Sleeping} 120 121 \subsection{Event FDs} 122 123 \subsection{Epoll} 124 125 \subsection{\texttt{io\_uring}} 126 127 \section{Reducing Latency} 154 Since \ats can be made ready by timers, \io operations or other events outside a clusre, this race can occur even if the \proc going to sleep is the only \proc awake. 155 As a result, improper handling of this race can lead to all \procs going to sleep and the system deadlocking. 156 157 Furthermore, the ``Race-to-Idle'' approach means that there may be contention on the data structure tracking sleepers. 158 Contention slowing down \procs attempting to sleep or wake-up can be tolerated. 159 These \procs are not doing useful work and therefore not contributing to overall performance. 160 However, notifying, checking if a \proc must be woken-up and doing so if needed, can significantly affect overall performance and must be low cost. 161 162 \subsection{Sleepers List} 163 Each cluster maintains a list of idle \procs, organized as a stack. 164 This ordering hopefully allows \proc at the tail to stay in idle sleep for extended period of times. 165 Because of these unbalanced performance requirements, the algorithm tracking sleepers is designed to have idle \proc handle as much of the work as possible. 166 The idle \procs maintain the of sleepers among themselves and notifying a sleeping \proc takes as little work as possible. 167 This approach means that maintaining the list is fairly straightforward. 168 The list can simply use a single lock per cluster and only \procs that are getting in and out of idle state will contend for that lock. 169 170 This approach also simplifies notification. 171 Indeed, \procs need to be notify when a new \at is readied, but they also must be notified during resizing, so the \gls{kthrd} can be joined. 172 This means that whichever entity removes idle \procs from the sleeper list must be able to do so in any order. 173 Using a simple lock over this data structure makes the removal much simpler than using a lock-free data structure. 174 The notification process then simply needs to wake-up the desired idle \proc, using \texttt{pthread\_cond\_signal}, \texttt{write} on an fd, etc., and the \proc will handle the rest. 175 176 \subsection{Reducing Latency} 177 As mentioned in this section, \procs going idle for extremely short periods of time is likely in certain common scenarios. 178 Therefore, the latency of doing a system call to read from and writing to the event fd can actually negatively affect overall performance in a notable way. 179 Is it important to reduce latency and contention of the notification as much as possible. 180 Figure~\ref{fig:idle1} shoes the basic idle sleep data structure. 181 For the notifiers, this data structure can cause contention on the lock and the event fd syscall can cause notable latency. 182 183 \begin{figure} 184 \centering 185 \input{idle2.pstex_t} 186 \caption[Improved Idle Sleep Data Structure]{Improved Idle Sleep Data Structure \smallskip\newline An atomic pointer is added to the list, pointing to the Event FD of the first \proc on the list.} 187 \label{fig:idle2} 188 \end{figure} 189 190 The contention is mostly due to the lock on the list needing to be held to get to the head \proc. 191 That lock can be contended by \procs attempting to go to sleep, \procs waking or notification attempts. 192 The contentention from the \procs attempting to go to sleep can be mitigated slightly by using \texttt{try\_acquire} instead, so the \procs simply continue searching for \ats if the lock is held. 193 This trick cannot be used for waking \procs since they are not in a state where they can run \ats. 194 However, it is worth nothing that notification does not strictly require accessing the list or the head \proc. 195 Therefore, contention can be reduced notably by having notifiers avoid the lock entirely and adding a pointer to the event fd of the first idle \proc, as in Figure~\ref{fig:idle2}. 196 To avoid contention between the notifiers, instead of simply reading the atomic pointer, notifiers atomically exchange it to \texttt{null} so only only notifier will contend on the system call. 197 198 \begin{figure} 199 \centering 200 \input{idle_state.pstex_t} 201 \caption[Improved Idle Sleep Data Structure]{Improved Idle Sleep Data Structure \smallskip\newline An atomic pointer is added to the list, pointing to the Event FD of the first \proc on the list.} 202 \label{fig:idle:state} 203 \end{figure} 204 205 The next optimization that can be done is to avoid the latency of the event fd when possible. 206 This can be done by adding what is effectively a benaphore\cit{benaphore} in front of the event fd. 207 A simple three state flag is added beside the event fd to avoid unnecessary system calls, as shown in Figure~\ref{fig:idle:state}. 208 The flag starts in state \texttt{SEARCH}, while the \proc is searching for \ats to run. 209 The \proc then confirms the sleep by atomically swaping the state to \texttt{SLEEP}. 210 If the previous state was still \texttt{SEARCH}, then the \proc does read the event fd. 211 Meanwhile, notifiers atomically exchange the state to \texttt{AWAKE} state. 212 if the previous state was \texttt{SLEEP}, then the notifier must write to the event fd. 213 However, if the notify arrives almost immediately after the \proc marks itself idle, then both reads and writes on the event fd can be omitted, which reduces latency notably. 214 This leads to the final data structure shown in Figure~\ref{fig:idle}. 215 216 \begin{figure} 217 \centering 218 \input{idle.pstex_t} 219 \caption[Low-latency Idle Sleep Data Structure]{Low-latency Idle Sleep Data Structure \smallskip\newline Each idle \proc is put unto a doubly-linked stack protected by a lock. 220 Each \proc has a private event FD with a benaphore in front of it. 221 The list also has an atomic pointer to the event fd and benaphore of the first \proc on the list.} 222 \label{fig:idle} 223 \end{figure} -
doc/theses/thierry_delisle_PhD/thesis/thesis.tex
r015925a re5d9274 80 80 %\usepackage{nomencl} % For a nomenclature (optional; available from ctan.org) 81 81 \usepackage{amsmath,amssymb,amstext} % Lots of math symbols and environments 82 \usepackage {xcolor}82 \usepackage[dvipsnames]{xcolor} 83 83 \usepackage{graphicx} % For including graphics 84 \usepackage{subcaption} 84 85 85 86 % Hyperlinks make it very easy to navigate an electronic document. … … 104 105 colorlinks=true, % false: boxed links; true: colored links 105 106 linkcolor=blue, % color of internal links 106 citecolor= green,% color of links to bibliography107 citecolor=OliveGreen, % color of links to bibliography 107 108 filecolor=magenta, % color of file links 108 109 urlcolor=cyan % color of external links … … 204 205 \newcommand\at{\gls{at}\xspace}% 205 206 \newcommand\ats{\glspl{at}\xspace}% 207 \newcommand\Proc{\Pls{proc}\xspace}% 206 208 \newcommand\proc{\gls{proc}\xspace}% 207 209 \newcommand\procs{\glspl{proc}\xspace}%
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