Changes in libcfa/src/concurrency/kernel.cfa [29cb302:ada0246d]

File:

• libcfa/src/concurrency/kernel.cfa (modified) (36 diffs)

libcfa/src/concurrency/kernel.cfa

@@ -118 +118 @@
 // Kernel Scheduling logic
 static $thread * __next_thread(cluster * this);
-static bool __has_next_thread(cluster * this);
 static void __run_thread(processor * this, $thread * dst);
+static $thread * __halt(processor * this);
+static bool __wake_one(cluster * cltr, bool was_empty);
 static bool __wake_proc(processor *);
-static bool __wake_one(struct __processor_id_t * id, cluster * cltr);
-static void __halt(processor * this);
 
 //-----------------------------------------------------------------------------
 // Kernel storage
-KERNEL_STORAGE(cluster,              mainCluster);
-KERNEL_STORAGE(processor,            mainProcessor);
-KERNEL_STORAGE($thread,              mainThread);
-KERNEL_STORAGE(__stack_t,            mainThreadCtx);
-KERNEL_STORAGE(__scheduler_RWLock_t, __scheduler_lock);
-#if !defined(__CFA_NO_STATISTICS__)
-KERNEL_STORAGE(__stats_t, mainProcStats);
-#endif
-
-cluster              * mainCluster;
-processor            * mainProcessor;
-$thread              * mainThread;
-__scheduler_RWLock_t * __scheduler_lock;
+KERNEL_STORAGE(cluster,         mainCluster);
+KERNEL_STORAGE(processor,       mainProcessor);
+KERNEL_STORAGE($thread, mainThread);
+KERNEL_STORAGE(__stack_t,       mainThreadCtx);
+
+cluster     * mainCluster;
+processor   * mainProcessor;
+$thread * mainThread;
 
 extern "C" {
@@ -150 +144 @@
 thread_local struct KernelThreadData kernelTLS __attribute__ ((tls_model ( "initial-exec" ))) = {
         NULL,                                                                                           // cannot use 0p
-        NULL,
         NULL,
         { 1, false, false },
@@ -197 +190 @@
 
 void ?{}( $thread & this, current_stack_info_t * info) with( this ) {
-        ticket = 1;
         state = Start;
         self_cor{ info };
@@ -205 +197 @@
         self_mon.recursion = 1;
         self_mon_p = &self_mon;
-        link.next = 0p;
-        link.prev = 0p;
+        next = 0p;
 
         node.next = 0p;
@@ -229 +220 @@
 static void * __invoke_processor(void * arg);
 
-void ?{}(processor & this, const char name[], cluster & _cltr) with( this ) {
+void ?{}(processor & this, const char name[], cluster & cltr) with( this ) {
         this.name = name;
-        this.cltr = &_cltr;
-        id = -1u;
+        this.cltr = &cltr;
         terminated{ 0 };
         destroyer = 0p;
@@ -245 +235 @@
 
         this.stack = __create_pthread( &this.kernel_thread, __invoke_processor, (void *)&this );
-        __atomic_fetch_add( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
 
         __cfadbg_print_safe(runtime_core, "Kernel : core %p created\n", &this);
@@ -265 +254 @@
 
         free( this.stack );
-
-        __atomic_fetch_sub( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
 }
 
@@ -272 +259 @@
         this.name = name;
         this.preemption_rate = preemption_rate;
-        this.nprocessors = 0;
         ready_queue{};
+        ready_queue_lock{};
 
         #if !defined(__CFA_NO_STATISTICS__)
                 print_stats = false;
-                stats = alloc();
-                __init_stats( stats );
         #endif
 
+        procs{ __get };
+        idles{ __get };
         threads{ __get };
 
@@ -290 +277 @@
 void ^?{}(cluster & this) {
         __kernel_io_shutdown( this, &this == mainCluster );
-
-        #if !defined(__CFA_NO_STATISTICS__)
-                if(this.print_stats) {
-                        __print_stats( this.stats );
-                }
-                free( this.stats );
-        #endif
 
         unregister(this);
@@ -315 +295 @@
         __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
 
-        // register the processor unless it's the main thread which is handled in the boot sequence
-        if(this != mainProcessor) {
-                this->id = doregister((__processor_id_t*)this);
-                // Lock the RWlock so no-one pushes/pops while we are changing the queue
-                uint_fast32_t last_size = ready_mutate_lock();
-
-                        // Adjust the ready queue size
-                        ready_queue_grow( this->cltr );
-
-                // Unlock the RWlock
-                ready_mutate_unlock( last_size );
-        }
+        doregister(this->cltr, this);
 
         {
@@ -339 +308 @@
                         readyThread = __next_thread( this->cltr );
 
+                        // If no ready thread
+                        if( readyThread == 0p ) {
+                                // Block until a thread is ready
+                                readyThread = __halt(this);
+                        }
+
                         // Check if we actually found a thread
                         if( readyThread ) {
                                 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
                                 /* paranoid */ verifyf( readyThread->state == Ready || readyThread->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", readyThread->state, readyThread->preempted);
-                                /* paranoid */ verifyf( readyThread->link.next == 0p, "Expected null got %p", readyThread->link.next );
-                                __builtin_prefetch( readyThread->context.SP );
+                                /* paranoid */ verifyf( readyThread->next == 0p, "Expected null got %p", readyThread->next );
 
                                 // We found a thread run it
@@ -351 +325 @@
                                 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
                         }
-                        else {
-                                // Block until a thread is ready
-                                __halt(this);
-                        }
                 }
 
@@ -360 +330 @@
         }
 
+        unregister(this->cltr, this);
+
         V( this->terminated );
 
-        // unregister the processor unless it's the main thread which is handled in the boot sequence
-        if(this != mainProcessor) {
-                // Lock the RWlock so no-one pushes/pops while we are changing the queue
-                uint_fast32_t last_size = ready_mutate_lock();
-
-                        // Adjust the ready queue size
-                        ready_queue_shrink( this->cltr );
-
-                        // Make sure we aren't on the idle queue
-                        #if !defined(__CFA_NO_STATISTICS__)
-                                bool removed =
-                        #endif
-                        unsafe_remove( this->cltr->idles, this );
-
-                        #if !defined(__CFA_NO_STATISTICS__)
-                                if(removed) __tls_stats()->ready.sleep.exits++;
-                        #endif
-
-                // Unlock the RWlock
-                ready_mutate_unlock( last_size );
-
-                // Finally we don't need the read_lock any more
-                unregister((__processor_id_t*)this);
-        }
-        else {
-                // HACK : the coroutine context switch expects this_thread to be set
-                // and it make sense for it to be set in all other cases except here
-                // fake it
-                kernelTLS.this_thread = mainThread;
-        }
-
         __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
+
+        // HACK : the coroutine context switch expects this_thread to be set
+        // and it make sense for it to be set in all other cases except here
+        // fake it
+        if( this == mainProcessor ) kernelTLS.this_thread = mainThread;
 }
 
@@ -414 +360 @@
         // Actually run the thread
         RUNNING:  while(true) {
-                thrd_dst->preempted = __NO_PREEMPTION;
-                thrd_dst->state = Active;
+                if(unlikely(thrd_dst->preempted)) {
+                        thrd_dst->preempted = __NO_PREEMPTION;
+                        verify(thrd_dst->state == Active  || thrd_dst->state == Rerun);
+                } else {
+                        verify(thrd_dst->state == Blocked || thrd_dst->state == Ready); // Ready means scheduled normally, blocked means rerun
+                        thrd_dst->state = Active;
+                }
 
                 __cfaabi_dbg_debug_do(
@@ -447 +398 @@
                 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
                         // The thread was preempted, reschedule it and reset the flag
-                        __schedule_thread( (__processor_id_t*)this, thrd_dst );
+                        __schedule_thread( thrd_dst );
                         break RUNNING;
                 }
 
-                if(unlikely(thrd_dst->state == Halted)) {
-                        // The thread has halted, it should never be scheduled/run again
-                        // We may need to wake someone up here since
-                        unpark( this->destroyer __cfaabi_dbg_ctx2 );
-                        this->destroyer = 0p;
-                        break RUNNING;
-                }
-
-                /* paranoid */ verify( thrd_dst->state == Active );
-                thrd_dst->state = Blocked;
-
                 // set state of processor coroutine to active and the thread to inactive
-                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
-                __cfaabi_dbg_debug_do( thrd_dst->park_result = old_ticket; )
-                switch(old_ticket) {
-                        case 1:
+                static_assert(sizeof(thrd_dst->state) == sizeof(int));
+                enum coroutine_state old_state = __atomic_exchange_n(&thrd_dst->state, Blocked, __ATOMIC_SEQ_CST);
+                __cfaabi_dbg_debug_do( thrd_dst->park_result = old_state; )
+                switch(old_state) {
+                        case Halted:
+                                // The thread has halted, it should never be scheduled/run again, leave it back to Halted and move on
+                                thrd_dst->state = Halted;
+
+                                // We may need to wake someone up here since
+                                unpark( this->destroyer __cfaabi_dbg_ctx2 );
+                                this->destroyer = 0p;
+                                break RUNNING;
+                        case Active:
                                 // This is case 1, the regular case, nothing more is needed
                                 break RUNNING;
-                        case 2:
+                        case Rerun:
                                 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
                                 // In this case, just run it again.
@@ -475 +424 @@
                         default:
                                 // This makes no sense, something is wrong abort
-                                abort();
+                                abort("Finished running a thread that was Blocked/Start/Primed %d\n", old_state);
                 }
         }
@@ -489 +438 @@
         $coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
         $thread * thrd_src = kernelTLS.this_thread;
-
-        #if !defined(__CFA_NO_STATISTICS__)
-                struct processor * last_proc = kernelTLS.this_processor;
-        #endif
 
         // Run the thread on this processor
@@ -508 +453 @@
         }
 
-        #if !defined(__CFA_NO_STATISTICS__)
-                if(last_proc != kernelTLS.this_processor) {
-                        __tls_stats()->ready.threads.migration++;
-                }
-        #endif
-
         /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
         /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too small.\n", thrd_src );
@@ -524 +463 @@
 // It effectively constructs a coroutine by stealing the pthread stack
 static void * __invoke_processor(void * arg) {
-        #if !defined( __CFA_NO_STATISTICS__ )
-                __stats_t local_stats;
-                __init_stats( &local_stats );
-                kernelTLS.this_stats = &local_stats;
-        #endif
-
         processor * proc = (processor *) arg;
         kernelTLS.this_processor = proc;
@@ -561 +494 @@
         __cfadbg_print_safe(runtime_core, "Kernel : core %p main ended (%p)\n", proc, &proc->runner);
 
-        #if !defined(__CFA_NO_STATISTICS__)
-                __tally_stats(proc->cltr->stats, &local_stats);
-        #endif
-
         return 0p;
 }
@@ -662 +591 @@
 // Scheduler routines
 // KERNEL ONLY
-void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
-        /* paranoid */ verify( thrd );
-        /* paranoid */ verify( thrd->state != Halted );
+void __schedule_thread( $thread * thrd ) with( *thrd->curr_cluster ) {
         /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
         /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
-        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
-                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
-        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
-                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
+        /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
+                          "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
+        /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active || thrd->state == Rerun,
+                          "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
         /* paranoid */ #endif
-        /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
+        /* paranoid */ verifyf( thrd->next == 0p, "Expected null got %p", thrd->next );
 
         if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
 
-        ready_schedule_lock  ( id );
-                push( thrd->curr_cluster, thrd );
-
-                #if !defined(__CFA_NO_STATISTICS__)
-                        bool woke =
-                #endif
-                        __wake_one(id, thrd->curr_cluster);
-
-                #if !defined(__CFA_NO_STATISTICS__)
-                        if(woke) __tls_stats()->ready.sleep.wakes++;
-                #endif
-        ready_schedule_unlock( id );
+        lock  ( ready_queue_lock __cfaabi_dbg_ctx2 );
+        bool was_empty = !(ready_queue != 0);
+        append( ready_queue, thrd );
+        unlock( ready_queue_lock );
+
+        __wake_one(thrd->curr_cluster, was_empty);
 
         /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
@@ -696 +617 @@
         /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
 
-        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
-                $thread * head = pop( this );
-        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
+        lock( ready_queue_lock __cfaabi_dbg_ctx2 );
+        $thread * head = pop_head( ready_queue );
+        unlock( ready_queue_lock );
 
         /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
@@ -704 +625 @@
 }
 
-// KERNEL ONLY
-static bool __has_next_thread(cluster * this) with( *this ) {
-        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
-
-        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
-                bool not_empty = query( this );
-        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
-
-        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
-        return not_empty;
-}
-
 // KERNEL ONLY unpark with out disabling interrupts
-void __unpark(  struct __processor_id_t * id, $thread * thrd __cfaabi_dbg_ctx_param2 ) {
+void __unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
+        static_assert(sizeof(thrd->state) == sizeof(int));
+
         // record activity
         __cfaabi_dbg_debug_do( char * old_caller = thrd->unpark_caller; )
         __cfaabi_dbg_record_thrd( *thrd, false, caller );
 
-        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
-        __cfaabi_dbg_debug_do( thrd->unpark_result = old_ticket; thrd->unpark_state = thrd->state; )
-        switch(old_ticket) {
-                case 1:
+        enum coroutine_state old_state = __atomic_exchange_n(&thrd->state, Rerun, __ATOMIC_SEQ_CST);
+        __cfaabi_dbg_debug_do( thrd->unpark_result = old_state; )
+        switch(old_state) {
+                case Active:
                         // Wake won the race, the thread will reschedule/rerun itself
                         break;
-                case 0:
+                case Blocked:
                         /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
-                        /* paranoid */ verify( thrd->state == Blocked );
 
                         // Wake lost the race,
-                        __schedule_thread( id, thrd );
+                        thrd->state = Blocked;
+                        __schedule_thread( thrd );
                         break;
+                case Rerun:
+                        abort("More than one thread attempted to schedule thread %p\n", thrd);
+                        break;
+                case Halted:
+                case Start:
+                case Primed:
                 default:
                         // This makes no sense, something is wrong abort
@@ -745 +662 @@
 
         disable_interrupts();
-        __unpark( (__processor_id_t*)kernelTLS.this_processor, thrd __cfaabi_dbg_ctx_fwd2 );
+        __unpark( thrd __cfaabi_dbg_ctx_fwd2 );
         enable_interrupts( __cfaabi_dbg_ctx );
 }
@@ -780 +697 @@
 
         $thread * thrd = kernelTLS.this_thread;
-        /* paranoid */ verify(thrd->state == Active);
+        /* paranoid */ verify(thrd->state == Active || thrd->state == Rerun);
 
         // SKULLDUGGERY: It is possible that we are preempting this thread just before
@@ -787 +704 @@
         // If that is the case, abandon the preemption.
         bool preempted = false;
-        if(thrd->link.next == 0p) {
+        if(thrd->next == 0p) {
                 preempted = true;
                 thrd->preempted = reason;
@@ -813 +730 @@
         __cfa_dbg_global_clusters.list{ __get };
         __cfa_dbg_global_clusters.lock{};
-
-        // Initialize the global scheduler lock
-        __scheduler_lock = (__scheduler_RWLock_t*)&storage___scheduler_lock;
-        (*__scheduler_lock){};
 
         // Initialize the main cluster
@@ -851 +764 @@
                 pending_preemption = false;
                 kernel_thread = pthread_self();
-                id = -1u;
 
                 runner{ &this };
                 __cfadbg_print_safe(runtime_core, "Kernel : constructed main processor context %p\n", &runner);
-
-                __atomic_fetch_add( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
         }
 
@@ -864 +774 @@
         (*mainProcessor){};
 
-        mainProcessor->id = doregister( (__processor_id_t*)mainProcessor);
-
         //initialize the global state variables
         kernelTLS.this_processor = mainProcessor;
         kernelTLS.this_thread    = mainThread;
 
-        #if !defined( __CFA_NO_STATISTICS__ )
-                kernelTLS.this_stats = (__stats_t *)& storage_mainProcStats;
-                __init_stats( kernelTLS.this_stats );
-        #endif
-
         // Enable preemption
         kernel_start_preemption();
@@ -880 +783 @@
         // Add the main thread to the ready queue
         // once resume is called on mainProcessor->runner the mainThread needs to be scheduled like any normal thread
-        __schedule_thread((__processor_id_t *)mainProcessor, mainThread);
+        __schedule_thread(mainThread);
 
         // SKULLDUGGERY: Force a context switch to the main processor to set the main thread's context to the current UNIX
@@ -924 +827 @@
         kernel_stop_preemption();
 
-        unregister((__processor_id_t*)mainProcessor);
-
         // Destroy the main processor and its context in reverse order of construction
         // These were manually constructed so we need manually destroy them
         void ^?{}(processor & this) with( this ){
                 /* paranoid */ verify( this.do_terminate == true );
-                __atomic_fetch_sub( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
-                __cfaabi_dbg_print_safe("Kernel : destroyed main processor context %p\n", &runner);
         }
 
@@ -937 +836 @@
 
         // Final step, destroy the main thread since it is no longer needed
-
         // Since we provided a stack to this taxk it will not destroy anything
         /* paranoid */ verify(mainThread->self_cor.stack.storage == (__stack_t*)(((uintptr_t)&storage_mainThreadCtx)| 0x1));
@@ -944 +842 @@
         ^(*mainCluster){};
 
-        ^(*__scheduler_lock){};
-
         ^(__cfa_dbg_global_clusters.list){};
         ^(__cfa_dbg_global_clusters.lock){};
@@ -955 +851 @@
 // Kernel Idle Sleep
 //=============================================================================================
+static $thread * __halt(processor * this) with( *this ) {
+        if( do_terminate ) return 0p;
+
+        // First, lock the cluster idle
+        lock( cltr->idle_lock __cfaabi_dbg_ctx2 );
+
+        // Check if we can find a thread
+        if( $thread * found = __next_thread( cltr ) ) {
+                unlock( cltr->idle_lock );
+                return found;
+        }
+
+        // Move this processor from the active list to the idle list
+        move_to_front(cltr->procs, cltr->idles, *this);
+
+        // Unlock the idle lock so we don't go to sleep with a lock
+        unlock    (cltr->idle_lock);
+
+        // We are ready to sleep
+        __cfadbg_print_safe(runtime_core, "Kernel : Processor %p ready to sleep\n", this);
+        wait( idle );
+
+        // We have woken up
+        __cfadbg_print_safe(runtime_core, "Kernel : Processor %p woke up and ready to run\n", this);
+
+        // Get ourself off the idle list
+        with( *cltr ) {
+                lock  (idle_lock __cfaabi_dbg_ctx2);
+                move_to_front(idles, procs, *this);
+                unlock(idle_lock);
+        }
+
+        // Don't check the ready queue again, we may not be in a position to run a thread
+        return 0p;
+}
+
 // Wake a thread from the front if there are any
-static bool __wake_one(struct __processor_id_t * id, cluster * this) {
-        /* paranoid */ verify( ready_schedule_islocked( id ) );
-
-        // Check if there is a sleeping processor
-        processor * p = pop(this->idles);
-
-        // If no one is sleeping, we are done
-        if( 0p == p ) return false;
-
-        // We found a processor, wake it up
-        post( p->idle );
-
+static bool __wake_one(cluster * this, __attribute__((unused)) bool force) {
+        // if we don't want to force check if we know it's false
+        // if( !this->idles.head && !force ) return false;
+
+        // First, lock the cluster idle
+        lock( this->idle_lock __cfaabi_dbg_ctx2 );
+
+        // Check if there is someone to wake up
+        if( !this->idles.head ) {
+                // Nope unlock and return false
+                unlock( this->idle_lock );
+                return false;
+        }
+
+        // Wake them up
+        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this->idles.head);
+        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
+        post( this->idles.head->idle );
+
+        // Unlock and return true
+        unlock( this->idle_lock );
         return true;
 }
@@ -981 +922 @@
 
         return ret;
-}
-
-static void __halt(processor * this) with( *this ) {
-        if( do_terminate ) return;
-
-        #if !defined(__CFA_NO_STATISTICS__)
-                __tls_stats()->ready.sleep.halts++;
-        #endif
-        // Push self to queue
-        push(cltr->idles, *this);
-
-        // Makre sure we don't miss a thread
-        if( __has_next_thread(cltr) ) {
-                // A thread was posted, make sure a processor is woken up
-                struct __processor_id_t *id = (struct __processor_id_t *) this;
-                ready_schedule_lock  ( id );
-                        __wake_one( id, cltr );
-                ready_schedule_unlock( id );
-                #if !defined(__CFA_NO_STATISTICS__)
-                        __tls_stats()->ready.sleep.cancels++;
-                #endif
-        }
-
-        wait( idle );
 }
 
@@ -1161 +1078 @@
         cltr->nthreads -= 1;
         unlock(cltr->thread_list_lock);
+}
+
+void doregister( cluster * cltr, processor * proc ) {
+        lock      (cltr->idle_lock __cfaabi_dbg_ctx2);
+        cltr->nprocessors += 1;
+        push_front(cltr->procs, *proc);
+        unlock    (cltr->idle_lock);
+}
+
+void unregister( cluster * cltr, processor * proc ) {
+        lock  (cltr->idle_lock __cfaabi_dbg_ctx2);
+        remove(cltr->procs, *proc );
+        cltr->nprocessors -= 1;
+        unlock(cltr->idle_lock);
 }