X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=rts%2FCapability.c;h=ce6ecebd7214fdf7f4884b14208d0d5cb1a2ed72;hp=0415092a0308d5556e12a16a5125f4a6a8c321ba;hb=7effbbbbdfe7eb05c6402fa9337e358e7e9fadde;hpb=5a2769f0273dd389977e8283375e7920d183bdd4 diff --git a/rts/Capability.c b/rts/Capability.c index 0415092..ce6eceb 100644 --- a/rts/Capability.c +++ b/rts/Capability.c @@ -18,27 +18,45 @@ #include "PosixSource.h" #include "Rts.h" -#include "RtsUtils.h" -#include "RtsFlags.h" -#include "STM.h" -#include "OSThreads.h" + #include "Capability.h" #include "Schedule.h" #include "Sparks.h" #include "Trace.h" +#include "sm/GC.h" // for gcWorkerThread() +#include "STM.h" +#include "RtsUtils.h" // one global capability, this is the Capability for non-threaded // builds, and for +RTS -N1 Capability MainCapability; -nat n_capabilities; +nat n_capabilities = 0; Capability *capabilities = NULL; // Holds the Capability which last became free. This is used so that // an in-call has a chance of quickly finding a free Capability. // Maintaining a global free list of Capabilities would require global // locking, so we don't do that. -Capability *last_free_capability; +Capability *last_free_capability = NULL; + +/* GC indicator, in scope for the scheduler, init'ed to false */ +volatile StgWord waiting_for_gc = 0; + +/* Let foreign code get the current Capability -- assuming there is one! + * This is useful for unsafe foreign calls because they are called with + * the current Capability held, but they are not passed it. For example, + * see see the integer-gmp package which calls allocateLocal() in its + * stgAllocForGMP() function (which gets called by gmp functions). + * */ +Capability * rts_unsafeGetMyCapability (void) +{ +#if defined(THREADED_RTS) + return myTask()->cap; +#else + return &MainCapability; +#endif +} #if defined(THREADED_RTS) STATIC_INLINE rtsBool @@ -51,29 +69,96 @@ globalWorkToDo (void) #endif #if defined(THREADED_RTS) -STATIC_INLINE rtsBool -anyWorkForMe( Capability *cap, Task *task ) +StgClosure * +findSpark (Capability *cap) { - if (task->tso != NULL) { - // A bound task only runs if its thread is on the run queue of - // the capability on which it was woken up. Otherwise, we - // can't be sure that we have the right capability: the thread - // might be woken up on some other capability, and task->cap - // could change under our feet. - return !emptyRunQueue(cap) && cap->run_queue_hd->bound == task; - } else { - // A vanilla worker task runs if either there is a lightweight - // thread at the head of the run queue, or the run queue is - // empty and (there are sparks to execute, or there is some - // other global condition to check, such as threads blocked on - // blackholes). - if (emptyRunQueue(cap)) { - return !emptySparkPoolCap(cap) - || !emptyWakeupQueue(cap) - || globalWorkToDo(); - } else - return cap->run_queue_hd->bound == NULL; + Capability *robbed; + StgClosurePtr spark; + rtsBool retry; + nat i = 0; + + if (!emptyRunQueue(cap) || cap->returning_tasks_hd != NULL) { + // If there are other threads, don't try to run any new + // sparks: sparks might be speculative, we don't want to take + // resources away from the main computation. + return 0; + } + + do { + retry = rtsFalse; + + // first try to get a spark from our own pool. + // We should be using reclaimSpark(), because it works without + // needing any atomic instructions: + // spark = reclaimSpark(cap->sparks); + // However, measurements show that this makes at least one benchmark + // slower (prsa) and doesn't affect the others. + spark = tryStealSpark(cap); + if (spark != NULL) { + cap->sparks_converted++; + + // Post event for running a spark from capability's own pool. + traceEventRunSpark(cap, cap->r.rCurrentTSO); + + return spark; + } + if (!emptySparkPoolCap(cap)) { + retry = rtsTrue; + } + + if (n_capabilities == 1) { return NULL; } // makes no sense... + + debugTrace(DEBUG_sched, + "cap %d: Trying to steal work from other capabilities", + cap->no); + + /* visit cap.s 0..n-1 in sequence until a theft succeeds. We could + start at a random place instead of 0 as well. */ + for ( i=0 ; i < n_capabilities ; i++ ) { + robbed = &capabilities[i]; + if (cap == robbed) // ourselves... + continue; + + if (emptySparkPoolCap(robbed)) // nothing to steal here + continue; + + spark = tryStealSpark(robbed); + if (spark == NULL && !emptySparkPoolCap(robbed)) { + // we conflicted with another thread while trying to steal; + // try again later. + retry = rtsTrue; + } + + if (spark != NULL) { + cap->sparks_converted++; + + traceEventStealSpark(cap, cap->r.rCurrentTSO, robbed->no); + + return spark; + } + // otherwise: no success, try next one + } + } while (retry); + + debugTrace(DEBUG_sched, "No sparks stolen"); + return NULL; +} + +// Returns True if any spark pool is non-empty at this moment in time +// The result is only valid for an instant, of course, so in a sense +// is immediately invalid, and should not be relied upon for +// correctness. +rtsBool +anySparks (void) +{ + nat i; + + for (i=0; i < n_capabilities; i++) { + if (!emptySparkPoolCap(&capabilities[i])) { + return rtsTrue; + } } + return rtsFalse; } #endif @@ -88,10 +173,10 @@ STATIC_INLINE void newReturningTask (Capability *cap, Task *task) { ASSERT_LOCK_HELD(&cap->lock); - ASSERT(task->return_link == NULL); + ASSERT(task->next == NULL); if (cap->returning_tasks_hd) { - ASSERT(cap->returning_tasks_tl->return_link == NULL); - cap->returning_tasks_tl->return_link = task; + ASSERT(cap->returning_tasks_tl->next == NULL); + cap->returning_tasks_tl->next = task; } else { cap->returning_tasks_hd = task; } @@ -105,11 +190,11 @@ popReturningTask (Capability *cap) Task *task; task = cap->returning_tasks_hd; ASSERT(task); - cap->returning_tasks_hd = task->return_link; + cap->returning_tasks_hd = task->next; if (!cap->returning_tasks_hd) { cap->returning_tasks_tl = NULL; } - task->return_link = NULL; + task->next = NULL; return task; } #endif @@ -135,28 +220,38 @@ initCapability( Capability *cap, nat i ) initMutex(&cap->lock); cap->running_task = NULL; // indicates cap is free cap->spare_workers = NULL; - cap->suspended_ccalling_tasks = NULL; + cap->suspended_ccalls = NULL; cap->returning_tasks_hd = NULL; cap->returning_tasks_tl = NULL; cap->wakeup_queue_hd = END_TSO_QUEUE; cap->wakeup_queue_tl = END_TSO_QUEUE; + cap->sparks_created = 0; + cap->sparks_converted = 0; + cap->sparks_pruned = 0; #endif - cap->f.stgGCEnter1 = (F_)__stg_gc_enter_1; - cap->f.stgGCFun = (F_)__stg_gc_fun; + cap->f.stgEagerBlackholeInfo = (W_)&__stg_EAGER_BLACKHOLE_info; + cap->f.stgGCEnter1 = (StgFunPtr)__stg_gc_enter_1; + cap->f.stgGCFun = (StgFunPtr)__stg_gc_fun; cap->mut_lists = stgMallocBytes(sizeof(bdescr *) * RtsFlags.GcFlags.generations, "initCapability"); + cap->saved_mut_lists = stgMallocBytes(sizeof(bdescr *) * + RtsFlags.GcFlags.generations, + "initCapability"); for (g = 0; g < RtsFlags.GcFlags.generations; g++) { cap->mut_lists[g] = NULL; } - cap->free_tvar_wait_queues = END_STM_WAIT_QUEUE; + cap->free_tvar_watch_queues = END_STM_WATCH_QUEUE; + cap->free_invariant_check_queues = END_INVARIANT_CHECK_QUEUE; cap->free_trec_chunks = END_STM_CHUNK_LIST; cap->free_trec_headers = NO_TREC; cap->transaction_tokens = 0; + cap->context_switch = 0; + cap->pinned_object_block = NULL; } /* --------------------------------------------------------------------------- @@ -214,6 +309,19 @@ initCapabilities( void ) } /* ---------------------------------------------------------------------------- + * setContextSwitches: cause all capabilities to context switch as + * soon as possible. + * ------------------------------------------------------------------------- */ + +void setContextSwitches(void) +{ + nat i; + for (i=0; i < n_capabilities; i++) { + contextSwitchCapability(&capabilities[i]); + } +} + +/* ---------------------------------------------------------------------------- * Give a Capability to a Task. The task must currently be sleeping * on its condition variable. * @@ -233,10 +341,9 @@ giveCapabilityToTask (Capability *cap USED_IF_DEBUG, Task *task) { ASSERT_LOCK_HELD(&cap->lock); ASSERT(task->cap == cap); - trace(TRACE_sched | DEBUG_sched, - "passing capability %d to %s %p", - cap->no, task->tso ? "bound task" : "worker", - (void *)task->id); + debugTrace(DEBUG_sched, "passing capability %d to %s %p", + cap->no, task->incall->tso ? "bound task" : "worker", + (void *)task->id); ACQUIRE_LOCK(&task->lock); task->wakeup = rtsTrue; // the wakeup flag is needed because signalCondition() doesn't @@ -257,7 +364,8 @@ giveCapabilityToTask (Capability *cap USED_IF_DEBUG, Task *task) #if defined(THREADED_RTS) void -releaseCapability_ (Capability* cap) +releaseCapability_ (Capability* cap, + rtsBool always_wakeup) { Task *task; @@ -275,12 +383,22 @@ releaseCapability_ (Capability* cap) return; } + if (waiting_for_gc == PENDING_GC_SEQ) { + last_free_capability = cap; // needed? + debugTrace(DEBUG_sched, "GC pending, set capability %d free", cap->no); + return; + } + + // If the next thread on the run queue is a bound thread, // give this Capability to the appropriate Task. if (!emptyRunQueue(cap) && cap->run_queue_hd->bound) { // Make sure we're not about to try to wake ourselves up - ASSERT(task != cap->run_queue_hd->bound); - task = cap->run_queue_hd->bound; + // ASSERT(task != cap->run_queue_hd->bound); + // assertion is false: in schedule() we force a yield after + // ThreadBlocked, but the thread may be back on the run queue + // by now. + task = cap->run_queue_hd->bound->task; giveCapabilityToTask(cap,task); return; } @@ -293,15 +411,16 @@ releaseCapability_ (Capability* cap) if (sched_state < SCHED_SHUTTING_DOWN || !emptyRunQueue(cap)) { debugTrace(DEBUG_sched, "starting new worker on capability %d", cap->no); - startWorkerTask(cap, workerStart); + startWorkerTask(cap); return; } } // If we have an unbound thread on the run queue, or if there's // anything else to do, give the Capability to a worker thread. - if (!emptyRunQueue(cap) || !emptyWakeupQueue(cap) - || !emptySparkPoolCap(cap) || globalWorkToDo()) { + if (always_wakeup || + !emptyRunQueue(cap) || !emptyWakeupQueue(cap) || + !emptySparkPoolCap(cap) || globalWorkToDo()) { if (cap->spare_workers) { giveCapabilityToTask(cap,cap->spare_workers); // The worker Task pops itself from the queue; @@ -310,14 +429,22 @@ releaseCapability_ (Capability* cap) } last_free_capability = cap; - trace(TRACE_sched | DEBUG_sched, "freeing capability %d", cap->no); + debugTrace(DEBUG_sched, "freeing capability %d", cap->no); } void releaseCapability (Capability* cap USED_IF_THREADS) { ACQUIRE_LOCK(&cap->lock); - releaseCapability_(cap); + releaseCapability_(cap, rtsFalse); + RELEASE_LOCK(&cap->lock); +} + +void +releaseAndWakeupCapability (Capability* cap USED_IF_THREADS) +{ + ACQUIRE_LOCK(&cap->lock); + releaseCapability_(cap, rtsTrue); RELEASE_LOCK(&cap->lock); } @@ -335,15 +462,13 @@ releaseCapabilityAndQueueWorker (Capability* cap USED_IF_THREADS) // in which case it is not replaced on the spare_worker queue. // This happens when the system is shutting down (see // Schedule.c:workerStart()). - // Also, be careful to check that this task hasn't just exited - // Haskell to do a foreign call (task->suspended_tso). - if (!isBoundTask(task) && !task->stopped && !task->suspended_tso) { + if (!isBoundTask(task) && !task->stopped) { task->next = cap->spare_workers; cap->spare_workers = task; } // Bound tasks just float around attached to their TSOs. - releaseCapability_(cap); + releaseCapability_(cap,rtsFalse); RELEASE_LOCK(&cap->lock); } @@ -374,17 +499,20 @@ waitForReturnCapability (Capability **pCap, Task *task) if (cap == NULL) { // Try last_free_capability first cap = last_free_capability; - if (!cap->running_task) { + if (cap->running_task) { nat i; // otherwise, search for a free capability + cap = NULL; for (i = 0; i < n_capabilities; i++) { - cap = &capabilities[i]; - if (!cap->running_task) { + if (!capabilities[i].running_task) { + cap = &capabilities[i]; break; } } - // Can't find a free one, use last_free_capability. - cap = last_free_capability; + if (cap == NULL) { + // Can't find a free one, use last_free_capability. + cap = last_free_capability; + } } // record the Capability as the one this Task is now assocated with. @@ -434,7 +562,7 @@ waitForReturnCapability (Capability **pCap, Task *task) ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task); - trace(TRACE_sched | DEBUG_sched, "resuming capability %d", cap->no); + debugTrace(DEBUG_sched, "resuming capability %d", cap->no); *pCap = cap; #endif @@ -450,9 +578,13 @@ yieldCapability (Capability** pCap, Task *task) { Capability *cap = *pCap; - // The fast path has no locking, if we don't enter this while loop + if (waiting_for_gc == PENDING_GC_PAR) { + traceEventGcStart(cap); + gcWorkerThread(cap); + traceEventGcEnd(cap); + return; + } - while ( cap->returning_tasks_hd != NULL || !anyWorkForMe(cap,task) ) { debugTrace(DEBUG_sched, "giving up capability %d", cap->no); // We must now release the capability and wait to be woken up @@ -478,7 +610,7 @@ yieldCapability (Capability** pCap, Task *task) continue; } - if (task->tso == NULL) { + if (task->incall->tso == NULL) { ASSERT(cap->spare_workers != NULL); // if we're not at the front of the queue, release it // again. This is unlikely to happen. @@ -495,9 +627,8 @@ yieldCapability (Capability** pCap, Task *task) break; } - trace(TRACE_sched | DEBUG_sched, "resuming capability %d", cap->no); + debugTrace(DEBUG_sched, "resuming capability %d", cap->no); ASSERT(cap->running_task == task); - } *pCap = cap; @@ -514,83 +645,58 @@ yieldCapability (Capability** pCap, Task *task) * ------------------------------------------------------------------------- */ void -wakeupThreadOnCapability (Capability *cap, StgTSO *tso) +wakeupThreadOnCapability (Capability *my_cap, + Capability *other_cap, + StgTSO *tso) { - ASSERT(tso->cap == cap); - ASSERT(tso->bound ? tso->bound->cap == cap : 1); + ACQUIRE_LOCK(&other_cap->lock); - ACQUIRE_LOCK(&cap->lock); - if (cap->running_task == NULL) { + // ASSUMES: cap->lock is held (asserted in wakeupThreadOnCapability) + if (tso->bound) { + ASSERT(tso->bound->task->cap == tso->cap); + tso->bound->task->cap = other_cap; + } + tso->cap = other_cap; + + ASSERT(tso->bound ? tso->bound->task->cap == other_cap : 1); + + if (other_cap->running_task == NULL) { // nobody is running this Capability, we can add our thread // directly onto the run queue and start up a Task to run it. - appendToRunQueue(cap,tso); - // start it up - cap->running_task = myTask(); // precond for releaseCapability_() - trace(TRACE_sched, "resuming capability %d", cap->no); - releaseCapability_(cap); + other_cap->running_task = myTask(); + // precond for releaseCapability_() and appendToRunQueue() + + appendToRunQueue(other_cap,tso); + + releaseCapability_(other_cap,rtsFalse); } else { - appendToWakeupQueue(cap,tso); + appendToWakeupQueue(my_cap,other_cap,tso); + other_cap->context_switch = 1; // someone is running on this Capability, so it cannot be // freed without first checking the wakeup queue (see // releaseCapability_). } - RELEASE_LOCK(&cap->lock); -} - -/* ---------------------------------------------------------------------------- - * prodCapabilities - * - * Used to indicate that the interrupted flag is now set, or some - * other global condition that might require waking up a Task on each - * Capability. - * ------------------------------------------------------------------------- */ - -static void -prodCapabilities(rtsBool all) -{ - nat i; - Capability *cap; - Task *task; - - for (i=0; i < n_capabilities; i++) { - cap = &capabilities[i]; - ACQUIRE_LOCK(&cap->lock); - if (!cap->running_task) { - if (cap->spare_workers) { - trace(TRACE_sched, "resuming capability %d", cap->no); - task = cap->spare_workers; - ASSERT(!task->stopped); - giveCapabilityToTask(cap,task); - if (!all) { - RELEASE_LOCK(&cap->lock); - return; - } - } - } - RELEASE_LOCK(&cap->lock); - } - return; -} -void -prodAllCapabilities (void) -{ - prodCapabilities(rtsTrue); + RELEASE_LOCK(&other_cap->lock); } /* ---------------------------------------------------------------------------- - * prodOneCapability + * prodCapability * - * Like prodAllCapabilities, but we only require a single Task to wake - * up in order to service some global event, such as checking for - * deadlock after some idle time has passed. + * If a Capability is currently idle, wake up a Task on it. Used to + * get every Capability into the GC. * ------------------------------------------------------------------------- */ void -prodOneCapability (void) +prodCapability (Capability *cap, Task *task) { - prodCapabilities(rtsFalse); + ACQUIRE_LOCK(&cap->lock); + if (!cap->running_task) { + cap->running_task = task; + releaseCapability_(cap,rtsTrue); + } + RELEASE_LOCK(&cap->lock); } /* ---------------------------------------------------------------------------- @@ -609,15 +715,21 @@ prodOneCapability (void) * ------------------------------------------------------------------------- */ void -shutdownCapability (Capability *cap, Task *task) +shutdownCapability (Capability *cap, Task *task, rtsBool safe) { nat i; - ASSERT(sched_state == SCHED_SHUTTING_DOWN); - task->cap = cap; - for (i = 0; i < 50; i++) { + // Loop indefinitely until all the workers have exited and there + // are no Haskell threads left. We used to bail out after 50 + // iterations of this loop, but that occasionally left a worker + // running which caused problems later (the closeMutex() below + // isn't safe, for one thing). + + for (i = 0; /* i < 50 */; i++) { + ASSERT(sched_state == SCHED_SHUTTING_DOWN); + debugTrace(DEBUG_sched, "shutting down capability %d, attempt %d", cap->no, i); ACQUIRE_LOCK(&cap->lock); @@ -628,20 +740,73 @@ shutdownCapability (Capability *cap, Task *task) continue; } cap->running_task = task; + + if (cap->spare_workers) { + // Look for workers that have died without removing + // themselves from the list; this could happen if the OS + // summarily killed the thread, for example. This + // actually happens on Windows when the system is + // terminating the program, and the RTS is running in a + // DLL. + Task *t, *prev; + prev = NULL; + for (t = cap->spare_workers; t != NULL; t = t->next) { + if (!osThreadIsAlive(t->id)) { + debugTrace(DEBUG_sched, + "worker thread %p has died unexpectedly", (void *)t->id); + if (!prev) { + cap->spare_workers = t->next; + } else { + prev->next = t->next; + } + prev = t; + } + } + } + if (!emptyRunQueue(cap) || cap->spare_workers) { debugTrace(DEBUG_sched, "runnable threads or workers still alive, yielding"); - releaseCapability_(cap); // this will wake up a worker + releaseCapability_(cap,rtsFalse); // this will wake up a worker RELEASE_LOCK(&cap->lock); yieldThread(); continue; } - debugTrace(DEBUG_sched, "capability %d is stopped.", cap->no); + + // If "safe", then busy-wait for any threads currently doing + // foreign calls. If we're about to unload this DLL, for + // example, we need to be sure that there are no OS threads + // that will try to return to code that has been unloaded. + // We can be a bit more relaxed when this is a standalone + // program that is about to terminate, and let safe=false. + if (cap->suspended_ccalls && safe) { + debugTrace(DEBUG_sched, + "thread(s) are involved in foreign calls, yielding"); + cap->running_task = NULL; + RELEASE_LOCK(&cap->lock); + // The IO manager thread might have been slow to start up, + // so the first attempt to kill it might not have + // succeeded. Just in case, try again - the kill message + // will only be sent once. + // + // To reproduce this deadlock: run ffi002(threaded1) + // repeatedly on a loaded machine. + ioManagerDie(); + yieldThread(); + continue; + } + + traceEventShutdown(cap); RELEASE_LOCK(&cap->lock); break; } // we now have the Capability, its run queue and spare workers // list are both empty. + + // ToDo: we can't drop this mutex, because there might still be + // threads performing foreign calls that will eventually try to + // return via resumeThread() and attempt to grab cap->lock. + // closeMutex(&cap->lock); } /* ---------------------------------------------------------------------------- @@ -669,4 +834,79 @@ tryGrabCapability (Capability *cap, Task *task) #endif /* THREADED_RTS */ +static void +freeCapability (Capability *cap) +{ + stgFree(cap->mut_lists); + stgFree(cap->saved_mut_lists); +#if defined(THREADED_RTS) + freeSparkPool(cap->sparks); +#endif +} + +void +freeCapabilities (void) +{ +#if defined(THREADED_RTS) + nat i; + for (i=0; i < n_capabilities; i++) { + freeCapability(&capabilities[i]); + } +#else + freeCapability(&MainCapability); +#endif +} + +/* --------------------------------------------------------------------------- + Mark everything directly reachable from the Capabilities. When + using multiple GC threads, each GC thread marks all Capabilities + for which (c `mod` n == 0), for Capability c and thread n. + ------------------------------------------------------------------------ */ + +void +markSomeCapabilities (evac_fn evac, void *user, nat i0, nat delta, + rtsBool prune_sparks USED_IF_THREADS) +{ + nat i; + Capability *cap; + InCall *incall; + + // Each GC thread is responsible for following roots from the + // Capability of the same number. There will usually be the same + // or fewer Capabilities as GC threads, but just in case there + // are more, we mark every Capability whose number is the GC + // thread's index plus a multiple of the number of GC threads. + for (i = i0; i < n_capabilities; i += delta) { + cap = &capabilities[i]; + evac(user, (StgClosure **)(void *)&cap->run_queue_hd); + evac(user, (StgClosure **)(void *)&cap->run_queue_tl); +#if defined(THREADED_RTS) + evac(user, (StgClosure **)(void *)&cap->wakeup_queue_hd); + evac(user, (StgClosure **)(void *)&cap->wakeup_queue_tl); +#endif + for (incall = cap->suspended_ccalls; incall != NULL; + incall=incall->next) { + evac(user, (StgClosure **)(void *)&incall->suspended_tso); + } +#if defined(THREADED_RTS) + if (prune_sparks) { + pruneSparkQueue (evac, user, cap); + } else { + traverseSparkQueue (evac, user, cap); + } +#endif + } + +#if !defined(THREADED_RTS) + evac(user, (StgClosure **)(void *)&blocked_queue_hd); + evac(user, (StgClosure **)(void *)&blocked_queue_tl); + evac(user, (StgClosure **)(void *)&sleeping_queue); +#endif +} + +void +markCapabilities (evac_fn evac, void *user) +{ + markSomeCapabilities(evac, user, 0, 1, rtsFalse); +}