source: libcfa/src/concurrency/kernel/cluster.cfa @ c18bf9e

ADTast-experimentalpthread-emulationqualifiedEnum
Last change on this file since c18bf9e was c18bf9e, checked in by Thierry Delisle <tdelisle@…>, 22 months ago

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1//
2// Cforall Version 1.0.0 Copyright (C) 2022 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// cluster.cfa -- file that includes helpers for subsystem that need cluster wide support
8//
9// Author           : Thierry Delisle
10// Created On       : Fri Mar 11 12:39:24 2022
11// Last Modified By :
12// Last Modified On :
13// Update Count     :
14//
15
16#define __cforall_thread__
17#define _GNU_SOURCE
18
19#include "bits/defs.hfa"
20#include "device/cpu.hfa"
21#include "kernel/cluster.hfa"
22#include "kernel/private.hfa"
23
24#include "stdlib.hfa"
25#include "limits.hfa"
26#include "math.hfa"
27
28#include "ready_subqueue.hfa"
29#include "io/types.hfa"
30
31#include <errno.h>
32#include <unistd.h>
33
34extern "C" {
35        #include <sys/syscall.h>  // __NR_xxx
36}
37
38// No overriden function, no environment variable, no define
39// fall back to a magic number
40#ifndef __CFA_MAX_PROCESSORS__
41        #define __CFA_MAX_PROCESSORS__ 1024
42#endif
43
44#if !defined(__CFA_NO_STATISTICS__)
45        #define __STATS(...) __VA_ARGS__
46#else
47        #define __STATS(...)
48#endif
49
50// returns the maximum number of processors the RWLock support
51__attribute__((weak)) unsigned __max_processors() libcfa_public {
52        const char * max_cores_s = getenv("CFA_MAX_PROCESSORS");
53        if(!max_cores_s) {
54                __cfadbg_print_nolock(ready_queue, "No CFA_MAX_PROCESSORS in ENV\n");
55                return __CFA_MAX_PROCESSORS__;
56        }
57
58        char * endptr = 0p;
59        long int max_cores_l = strtol(max_cores_s, &endptr, 10);
60        if(max_cores_l < 1 || max_cores_l > 65535) {
61                __cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS out of range : %ld\n", max_cores_l);
62                return __CFA_MAX_PROCESSORS__;
63        }
64        if('\0' != *endptr) {
65                __cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS not a decimal number : %s\n", max_cores_s);
66                return __CFA_MAX_PROCESSORS__;
67        }
68
69        return max_cores_l;
70}
71
72#if   defined(CFA_HAVE_LINUX_LIBRSEQ)
73        // No forward declaration needed
74        #define __kernel_rseq_register rseq_register_current_thread
75        #define __kernel_rseq_unregister rseq_unregister_current_thread
76#elif defined(CFA_HAVE_LINUX_RSEQ_H)
77        static void __kernel_raw_rseq_register  (void);
78        static void __kernel_raw_rseq_unregister(void);
79
80        #define __kernel_rseq_register __kernel_raw_rseq_register
81        #define __kernel_rseq_unregister __kernel_raw_rseq_unregister
82#else
83        // No forward declaration needed
84        // No initialization needed
85        static inline void noop(void) {}
86
87        #define __kernel_rseq_register noop
88        #define __kernel_rseq_unregister noop
89#endif
90
91//=======================================================================
92// Cluster wide reader-writer lock
93//=======================================================================
94void  ?{}(__scheduler_RWLock_t & this) {
95        this.max   = __max_processors();
96        this.alloc = 0;
97        this.ready = 0;
98        this.data  = alloc(this.max);
99        this.write_lock  = false;
100
101        /*paranoid*/ verify(__atomic_is_lock_free(sizeof(this.alloc), &this.alloc));
102        /*paranoid*/ verify(__atomic_is_lock_free(sizeof(this.ready), &this.ready));
103
104}
105void ^?{}(__scheduler_RWLock_t & this) {
106        free(this.data);
107}
108
109
110//=======================================================================
111// Lock-Free registering/unregistering of threads
112unsigned register_proc_id( void ) with(*__scheduler_lock) {
113        __kernel_rseq_register();
114
115        bool * handle = (bool *)&kernelTLS().sched_lock;
116
117        // Step - 1 : check if there is already space in the data
118        uint_fast32_t s = ready;
119
120        // Check among all the ready
121        for(uint_fast32_t i = 0; i < s; i++) {
122                bool * volatile * cell = (bool * volatile *)&data[i]; // Cforall is bugged and the double volatiles causes problems
123                /* paranoid */ verify( handle != *cell );
124
125                bool * null = 0p; // Re-write every loop since compare thrashes it
126                if( __atomic_load_n(cell, (int)__ATOMIC_RELAXED) == null
127                        && __atomic_compare_exchange_n( cell, &null, handle, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
128                        /* paranoid */ verify(i < ready);
129                        /* paranoid */ verify( (kernelTLS().sched_id = i, true) );
130                        return i;
131                }
132        }
133
134        if(max <= alloc) abort("Trying to create more than %ud processors", __scheduler_lock->max);
135
136        // Step - 2 : F&A to get a new spot in the array.
137        uint_fast32_t n = __atomic_fetch_add(&alloc, 1, __ATOMIC_SEQ_CST);
138        if(max <= n) abort("Trying to create more than %ud processors", __scheduler_lock->max);
139
140        // Step - 3 : Mark space as used and then publish it.
141        data[n] = handle;
142        while() {
143                unsigned copy = n;
144                if( __atomic_load_n(&ready, __ATOMIC_RELAXED) == n
145                        && __atomic_compare_exchange_n(&ready, &copy, n + 1, true, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
146                        break;
147                Pause();
148        }
149
150        // Return new spot.
151        /* paranoid */ verify(n < ready);
152        /* paranoid */ verify( (kernelTLS().sched_id = n, true) );
153        return n;
154}
155
156void unregister_proc_id( unsigned id ) with(*__scheduler_lock) {
157        /* paranoid */ verify(id < ready);
158        /* paranoid */ verify(id == kernelTLS().sched_id);
159        /* paranoid */ verify(data[id] == &kernelTLS().sched_lock);
160
161        bool * volatile * cell = (bool * volatile *)&data[id]; // Cforall is bugged and the double volatiles causes problems
162
163        __atomic_store_n(cell, 0p, __ATOMIC_RELEASE);
164
165        __kernel_rseq_unregister();
166}
167
168//-----------------------------------------------------------------------
169// Writer side : acquire when changing the ready queue, e.g. adding more
170//  queues or removing them.
171uint_fast32_t ready_mutate_lock( void ) with(*__scheduler_lock) {
172        /* paranoid */ verify( ! __preemption_enabled() );
173
174        // Step 1 : lock global lock
175        // It is needed to avoid processors that register mid Critical-Section
176        //   to simply lock their own lock and enter.
177        __atomic_acquire( &write_lock );
178
179        // Make sure we won't deadlock ourself
180        // Checking before acquiring the writer lock isn't safe
181        // because someone else could have locked us.
182        /* paranoid */ verify( ! kernelTLS().sched_lock );
183
184        // Step 2 : lock per-proc lock
185        // Processors that are currently being registered aren't counted
186        //   but can't be in read_lock or in the critical section.
187        // All other processors are counted
188        uint_fast32_t s = ready;
189        for(uint_fast32_t i = 0; i < s; i++) {
190                volatile bool * llock = data[i];
191                if(llock) __atomic_acquire( llock );
192        }
193
194        /* paranoid */ verify( ! __preemption_enabled() );
195        return s;
196}
197
198void ready_mutate_unlock( uint_fast32_t last_s ) with(*__scheduler_lock) {
199        /* paranoid */ verify( ! __preemption_enabled() );
200
201        // Step 1 : release local locks
202        // This must be done while the global lock is held to avoid
203        //   threads that where created mid critical section
204        //   to race to lock their local locks and have the writer
205        //   immidiately unlock them
206        // Alternative solution : return s in write_lock and pass it to write_unlock
207        for(uint_fast32_t i = 0; i < last_s; i++) {
208                volatile bool * llock = data[i];
209                if(llock) __atomic_store_n(llock, (bool)false, __ATOMIC_RELEASE);
210        }
211
212        // Step 2 : release global lock
213        /*paranoid*/ assert(true == write_lock);
214        __atomic_store_n(&write_lock, (bool)false, __ATOMIC_RELEASE);
215
216        /* paranoid */ verify( ! __preemption_enabled() );
217}
218
219//=======================================================================
220// Cluster growth
221static const unsigned __readyq_single_shard = 2;
222
223//-----------------------------------------------------------------------
224// Check that all the intrusive queues in the data structure are still consistent
225static void check_readyQ( cluster * cltr ) with (cltr->sched) {
226        #if defined(__CFA_WITH_VERIFY__)
227                {
228                        const unsigned lanes_count = readyQ.count;
229                        for( idx ; lanes_count ) {
230                                __intrusive_lane_t & sl = readyQ.data[idx];
231                                assert(!readyQ.data[idx].lock);
232
233                                        if(is_empty(sl)) {
234                                                assert( sl.anchor.next == 0p );
235                                                assert( sl.anchor.ts   == -1llu );
236                                                assert( mock_head(sl)  == sl.prev );
237                                        } else {
238                                                assert( sl.anchor.next != 0p );
239                                                assert( sl.anchor.ts   != -1llu );
240                                                assert( mock_head(sl)  != sl.prev );
241                                        }
242                        }
243                }
244        #endif
245}
246
247// Call this function of the intrusive list was moved using memcpy
248// fixes the list so that the pointers back to anchors aren't left dangling
249static inline void fix(__intrusive_lane_t & ll) {
250        if(is_empty(ll)) {
251                verify(ll.anchor.next == 0p);
252                ll.prev = mock_head(ll);
253        }
254}
255
256static void assign_list(unsigned & valrq, unsigned & valio, dlist(processor) & list, unsigned count) {
257        processor * it = &list`first;
258        for(unsigned i = 0; i < count; i++) {
259                /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
260                it->rdq.id = valrq;
261                it->rdq.target = MAX;
262                valrq += __shard_factor.readyq;
263                #if defined(CFA_HAVE_LINUX_IO_URING_H)
264                        it->io.ctx->cq.id = valio;
265                        it->io.target = MAX;
266                        valio += __shard_factor.io;
267                #endif
268                it = &(*it)`next;
269        }
270}
271
272static void reassign_cltr_id(struct cluster * cltr) {
273        unsigned prefrq = 0;
274        unsigned prefio = 0;
275        assign_list(prefrq, prefio, cltr->procs.actives, cltr->procs.total - cltr->procs.idle);
276        assign_list(prefrq, prefio, cltr->procs.idles  , cltr->procs.idle );
277}
278
279#if defined(CFA_HAVE_LINUX_IO_URING_H)
280        static void assign_io($io_context ** data, size_t count, dlist(processor) & list) {
281                processor * it = &list`first;
282                while(it) {
283                        /* paranoid */ verifyf( it, "Unexpected null iterator\n");
284                        /* paranoid */ verifyf( it->io.ctx->cq.id < count, "Processor %p has id %u above count %zu\n", it, it->rdq.id, count);
285                        data[it->io.ctx->cq.id] = it->io.ctx;
286                        it = &(*it)`next;
287                }
288        }
289
290        static void reassign_cltr_io(struct cluster * cltr) {
291                assign_io(cltr->sched.io.data, cltr->sched.io.count, cltr->procs.actives);
292                assign_io(cltr->sched.io.data, cltr->sched.io.count, cltr->procs.idles  );
293        }
294#else
295        static void reassign_cltr_io(struct cluster *) {}
296#endif
297
298static void fix_times( __timestamp_t * volatile & tscs, unsigned count ) {
299        tscs = alloc(count, tscs`realloc);
300        for(i; count) {
301                tscs[i].tv = rdtscl();
302                tscs[i].ma = 0;
303        }
304}
305
306// Grow the ready queue
307void ready_queue_grow(struct cluster * cltr) {
308        int target = cltr->procs.total;
309
310        /* paranoid */ verify( ready_mutate_islocked() );
311        __cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue\n");
312
313        // Make sure that everything is consistent
314        /* paranoid */ check_readyQ( cltr );
315
316
317        // Find new count
318        // Make sure we always have atleast 1 list
319        size_t ocount = cltr->sched.readyQ.count;
320        size_t ncount = max(target * __shard_factor.readyq, __readyq_single_shard);
321
322        // Do we have to do anything?
323        if( ocount != ncount ) {
324
325                // grow the ready queue
326                with( cltr->sched ) {
327
328                        // Allocate new array (uses realloc and memcpies the data)
329                        readyQ.data = alloc( ncount, readyQ.data`realloc );
330
331                        // Fix the moved data
332                        for( idx; ocount ) {
333                                fix(readyQ.data[idx]);
334                        }
335
336                        // Construct new data
337                        for( idx; ocount ~ ncount) {
338                                (readyQ.data[idx]){};
339                        }
340
341                        // Update original count
342                        readyQ.count = ncount;
343                }
344
345
346                fix_times(cltr->sched.readyQ.tscs, cltr->sched.readyQ.count);
347        }
348
349        // Fix the io times
350        cltr->sched.io.count = target * __shard_factor.io;
351        fix_times(cltr->sched.io.tscs, cltr->sched.io.count);
352
353        // realloc the caches
354        cltr->sched.caches = alloc( target, cltr->sched.caches`realloc );
355
356        // reassign the clusters.
357        reassign_cltr_id(cltr);
358
359        cltr->sched.io.data = alloc( cltr->sched.io.count, cltr->sched.io.data`realloc );
360        reassign_cltr_io(cltr);
361
362        // Make sure that everything is consistent
363        /* paranoid */ check_readyQ( cltr );
364        /* paranoid */ verify( (target == 0) == (cltr->sched.caches == 0p) );
365
366        __cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue done\n");
367
368        /* paranoid */ verify( ready_mutate_islocked() );
369}
370
371// Shrink the ready queue
372void ready_queue_shrink(struct cluster * cltr) {
373        /* paranoid */ verify( ready_mutate_islocked() );
374        __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue\n");
375
376        // Make sure that everything is consistent
377        /* paranoid */ check_readyQ( cltr );
378
379        int target = cltr->procs.total;
380
381        with( cltr->sched ) {
382                // Remember old count
383                size_t ocount = readyQ.count;
384
385                // Find new count
386                // Make sure we always have atleast 1 list
387                size_t ncount = max(target * __shard_factor.readyq, __readyq_single_shard);
388                /* paranoid */ verifyf( ocount >= ncount, "Error in shrinking size calculation, %zu >= %zu", ocount, ncount );
389                /* paranoid */ verifyf( ncount == target * __shard_factor.readyq || ncount == __readyq_single_shard,
390                /* paranoid */          "Error in shrinking size calculation, expected %u or %u, got %zu", target * __shard_factor.readyq, __readyq_single_shard, ncount );
391
392                readyQ.count = ncount;
393
394                // for printing count the number of displaced threads
395                #if defined(__CFA_DEBUG_PRINT__) || defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
396                        __attribute__((unused)) size_t displaced = 0;
397                #endif
398
399                // redistribute old data
400                for( idx; ncount ~ ocount) {
401                        // Lock is not strictly needed but makes checking invariants much easier
402                        __attribute__((unused)) bool locked = __atomic_try_acquire(&readyQ.data[idx].lock);
403                        verify(locked);
404
405                        // As long as we can pop from this lane to push the threads somewhere else in the queue
406                        while(!is_empty(readyQ.data[idx])) {
407                                struct thread$ * thrd;
408                                unsigned long long _;
409                                [thrd, _] = pop(readyQ.data[idx]);
410
411                                push(cltr, thrd, true);
412
413                                // for printing count the number of displaced threads
414                                #if defined(__CFA_DEBUG_PRINT__) || defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
415                                        displaced++;
416                                #endif
417                        }
418
419                        // Unlock the lane
420                        __atomic_unlock(&readyQ.data[idx].lock);
421
422                        // TODO print the queue statistics here
423
424                        ^(readyQ.data[idx]){};
425                }
426
427                __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue displaced %zu threads\n", displaced);
428
429                // Allocate new array (uses realloc and memcpies the data)
430                readyQ.data = alloc( ncount, readyQ.data`realloc );
431
432                // Fix the moved data
433                for( idx; ncount ) {
434                        fix(readyQ.data[idx]);
435                }
436
437                fix_times(readyQ.tscs, ncount);
438        }
439        cltr->sched.caches = alloc( target, cltr->sched.caches`realloc );
440
441        // Fix the io times
442        cltr->sched.io.count = target * __shard_factor.io;
443        fix_times(cltr->sched.io.tscs, cltr->sched.io.count);
444
445        reassign_cltr_id(cltr);
446
447        cltr->sched.io.data = alloc( cltr->sched.io.count, cltr->sched.io.data`realloc );
448        reassign_cltr_io(cltr);
449
450        // Make sure that everything is consistent
451        /* paranoid */ verify( (target == 0) == (cltr->sched.caches == 0p) );
452        /* paranoid */ check_readyQ( cltr );
453
454        __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue done\n");
455        /* paranoid */ verify( ready_mutate_islocked() );
456}
457
458void ready_queue_close(struct cluster * cltr) {
459        free( cltr->sched.readyQ.data );
460        free( cltr->sched.readyQ.tscs );
461        cltr->sched.readyQ.data = 0p;
462        cltr->sched.readyQ.tscs = 0p;
463        cltr->sched.readyQ.count = 0;
464
465        free( cltr->sched.io.tscs );
466        free( cltr->sched.caches );
467}
468
469// Ctor
470void ?{}( __intrusive_lane_t & this ) {
471        this.lock = false;
472        this.prev = mock_head(this);
473        this.anchor.next = 0p;
474        this.anchor.ts   = -1llu;
475        #if !defined(__CFA_NO_STATISTICS__)
476                this.cnt  = 0;
477        #endif
478
479        // We add a boat-load of assertions here because the anchor code is very fragile
480        /* paranoid */ _Static_assert( offsetof( thread$, link ) == offsetof(__intrusive_lane_t, anchor) );
481        /* paranoid */ verify( offsetof( thread$, link ) == offsetof(__intrusive_lane_t, anchor) );
482        /* paranoid */ verify( ((uintptr_t)( mock_head(this) ) + offsetof( thread$, link )) == (uintptr_t)(&this.anchor) );
483        /* paranoid */ verify( &mock_head(this)->link.next == &this.anchor.next );
484        /* paranoid */ verify( &mock_head(this)->link.ts   == &this.anchor.ts   );
485        /* paranoid */ verify( mock_head(this)->link.next == 0p );
486        /* paranoid */ verify( mock_head(this)->link.ts   == -1llu  );
487        /* paranoid */ verify( mock_head(this) == this.prev );
488        /* paranoid */ verify( __alignof__(__intrusive_lane_t) == 128 );
489        /* paranoid */ verify( __alignof__(this) == 128 );
490        /* paranoid */ verifyf( ((intptr_t)(&this) % 128) == 0, "Expected address to be aligned %p %% 128 == %zd", &this, ((intptr_t)(&this) % 128) );
491}
492
493// Dtor is trivial
494void ^?{}( __intrusive_lane_t & this ) {
495        // Make sure the list is empty
496        /* paranoid */ verify( this.anchor.next == 0p );
497        /* paranoid */ verify( this.anchor.ts   == -1llu );
498        /* paranoid */ verify( mock_head(this)  == this.prev );
499}
500
501#if   defined(CFA_HAVE_LINUX_LIBRSEQ)
502        // No definition needed
503#elif defined(CFA_HAVE_LINUX_RSEQ_H)
504
505        #if defined( __x86_64 ) || defined( __i386 )
506                #define RSEQ_SIG        0x53053053
507        #elif defined( __ARM_ARCH )
508                #ifdef __ARMEB__
509                #define RSEQ_SIG    0xf3def5e7      /* udf    #24035    ; 0x5de3 (ARMv6+) */
510                #else
511                #define RSEQ_SIG    0xe7f5def3      /* udf    #24035    ; 0x5de3 */
512                #endif
513        #endif
514
515        extern void __disable_interrupts_hard();
516        extern void __enable_interrupts_hard();
517
518        static void __kernel_raw_rseq_register  (void) {
519                /* paranoid */ verify( __cfaabi_rseq.cpu_id == RSEQ_CPU_ID_UNINITIALIZED );
520
521                // int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), 0, (sigset_t *)0p, _NSIG / 8);
522                int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), 0, RSEQ_SIG);
523                if(ret != 0) {
524                        int e = errno;
525                        switch(e) {
526                        case EINVAL: abort("KERNEL ERROR: rseq register invalid argument");
527                        case ENOSYS: abort("KERNEL ERROR: rseq register no supported");
528                        case EFAULT: abort("KERNEL ERROR: rseq register with invalid argument");
529                        case EBUSY : abort("KERNEL ERROR: rseq register already registered");
530                        case EPERM : abort("KERNEL ERROR: rseq register sig  argument  on unregistration does not match the signature received on registration");
531                        default: abort("KERNEL ERROR: rseq register unexpected return %d", e);
532                        }
533                }
534        }
535
536        static void __kernel_raw_rseq_unregister(void) {
537                /* paranoid */ verify( __cfaabi_rseq.cpu_id >= 0 );
538
539                // int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), RSEQ_FLAG_UNREGISTER, (sigset_t *)0p, _NSIG / 8);
540                int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), RSEQ_FLAG_UNREGISTER, RSEQ_SIG);
541                if(ret != 0) {
542                        int e = errno;
543                        switch(e) {
544                        case EINVAL: abort("KERNEL ERROR: rseq unregister invalid argument");
545                        case ENOSYS: abort("KERNEL ERROR: rseq unregister no supported");
546                        case EFAULT: abort("KERNEL ERROR: rseq unregister with invalid argument");
547                        case EBUSY : abort("KERNEL ERROR: rseq unregister already registered");
548                        case EPERM : abort("KERNEL ERROR: rseq unregister sig  argument  on unregistration does not match the signature received on registration");
549                        default: abort("KERNEL ERROR: rseq unregisteunexpected return %d", e);
550                        }
551                }
552        }
553#else
554        // No definition needed
555#endif
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