1 /* ---------------------------------------------------------------------------
3 * (c) The GHC Team, 2003-2006
7 * A Capability represent the token required to execute STG code,
8 * and all the state an OS thread/task needs to run Haskell code:
9 * its STG registers, a pointer to its TSO, a nursery etc. During
10 * STG execution, a pointer to the capabilitity is kept in a
11 * register (BaseReg; actually it is a pointer to cap->r).
13 * Only in an THREADED_RTS build will there be multiple capabilities,
14 * for non-threaded builds there is only one global capability, namely
17 * --------------------------------------------------------------------------*/
19 #include "PosixSource.h"
22 #include "Capability.h"
26 #include "sm/GC.h" // for gcWorkerThread()
30 // one global capability, this is the Capability for non-threaded
31 // builds, and for +RTS -N1
32 Capability MainCapability;
34 nat n_capabilities = 0;
35 Capability *capabilities = NULL;
37 // Holds the Capability which last became free. This is used so that
38 // an in-call has a chance of quickly finding a free Capability.
39 // Maintaining a global free list of Capabilities would require global
40 // locking, so we don't do that.
41 Capability *last_free_capability = NULL;
43 /* GC indicator, in scope for the scheduler, init'ed to false */
44 volatile StgWord waiting_for_gc = 0;
46 /* Let foreign code get the current Capability -- assuming there is one!
47 * This is useful for unsafe foreign calls because they are called with
48 * the current Capability held, but they are not passed it. For example,
49 * see see the integer-gmp package which calls allocateLocal() in its
50 * stgAllocForGMP() function (which gets called by gmp functions).
52 Capability * rts_unsafeGetMyCapability (void)
54 #if defined(THREADED_RTS)
57 return &MainCapability;
61 #if defined(THREADED_RTS)
65 return sched_state >= SCHED_INTERRUPTING
66 || recent_activity == ACTIVITY_INACTIVE; // need to check for deadlock
70 #if defined(THREADED_RTS)
72 findSpark (Capability *cap)
79 if (!emptyRunQueue(cap) || cap->returning_tasks_hd != NULL) {
80 // If there are other threads, don't try to run any new
81 // sparks: sparks might be speculative, we don't want to take
82 // resources away from the main computation.
89 // first try to get a spark from our own pool.
90 // We should be using reclaimSpark(), because it works without
91 // needing any atomic instructions:
92 // spark = reclaimSpark(cap->sparks);
93 // However, measurements show that this makes at least one benchmark
94 // slower (prsa) and doesn't affect the others.
95 spark = tryStealSpark(cap);
97 cap->sparks_converted++;
99 // Post event for running a spark from capability's own pool.
100 traceEventRunSpark(cap, cap->r.rCurrentTSO);
104 if (!emptySparkPoolCap(cap)) {
108 if (n_capabilities == 1) { return NULL; } // makes no sense...
110 debugTrace(DEBUG_sched,
111 "cap %d: Trying to steal work from other capabilities",
114 /* visit cap.s 0..n-1 in sequence until a theft succeeds. We could
115 start at a random place instead of 0 as well. */
116 for ( i=0 ; i < n_capabilities ; i++ ) {
117 robbed = &capabilities[i];
118 if (cap == robbed) // ourselves...
121 if (emptySparkPoolCap(robbed)) // nothing to steal here
124 spark = tryStealSpark(robbed);
125 if (spark == NULL && !emptySparkPoolCap(robbed)) {
126 // we conflicted with another thread while trying to steal;
132 cap->sparks_converted++;
134 traceEventStealSpark(cap, cap->r.rCurrentTSO, robbed->no);
138 // otherwise: no success, try next one
142 debugTrace(DEBUG_sched, "No sparks stolen");
146 // Returns True if any spark pool is non-empty at this moment in time
147 // The result is only valid for an instant, of course, so in a sense
148 // is immediately invalid, and should not be relied upon for
155 for (i=0; i < n_capabilities; i++) {
156 if (!emptySparkPoolCap(&capabilities[i])) {
164 /* -----------------------------------------------------------------------------
165 * Manage the returning_tasks lists.
167 * These functions require cap->lock
168 * -------------------------------------------------------------------------- */
170 #if defined(THREADED_RTS)
172 newReturningTask (Capability *cap, Task *task)
174 ASSERT_LOCK_HELD(&cap->lock);
175 ASSERT(task->next == NULL);
176 if (cap->returning_tasks_hd) {
177 ASSERT(cap->returning_tasks_tl->next == NULL);
178 cap->returning_tasks_tl->next = task;
180 cap->returning_tasks_hd = task;
182 cap->returning_tasks_tl = task;
186 popReturningTask (Capability *cap)
188 ASSERT_LOCK_HELD(&cap->lock);
190 task = cap->returning_tasks_hd;
192 cap->returning_tasks_hd = task->next;
193 if (!cap->returning_tasks_hd) {
194 cap->returning_tasks_tl = NULL;
201 /* ----------------------------------------------------------------------------
204 * The Capability is initially marked not free.
205 * ------------------------------------------------------------------------- */
208 initCapability( Capability *cap, nat i )
213 cap->in_haskell = rtsFalse;
215 cap->run_queue_hd = END_TSO_QUEUE;
216 cap->run_queue_tl = END_TSO_QUEUE;
218 #if defined(THREADED_RTS)
219 initMutex(&cap->lock);
220 cap->running_task = NULL; // indicates cap is free
221 cap->spare_workers = NULL;
222 cap->n_spare_workers = 0;
223 cap->suspended_ccalls = NULL;
224 cap->returning_tasks_hd = NULL;
225 cap->returning_tasks_tl = NULL;
226 cap->inbox = (Message*)END_TSO_QUEUE;
227 cap->sparks_created = 0;
229 cap->sparks_converted = 0;
231 cap->sparks_fizzled = 0;
234 cap->f.stgEagerBlackholeInfo = (W_)&__stg_EAGER_BLACKHOLE_info;
235 cap->f.stgGCEnter1 = (StgFunPtr)__stg_gc_enter_1;
236 cap->f.stgGCFun = (StgFunPtr)__stg_gc_fun;
238 cap->mut_lists = stgMallocBytes(sizeof(bdescr *) *
239 RtsFlags.GcFlags.generations,
241 cap->saved_mut_lists = stgMallocBytes(sizeof(bdescr *) *
242 RtsFlags.GcFlags.generations,
245 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
246 cap->mut_lists[g] = NULL;
249 cap->free_tvar_watch_queues = END_STM_WATCH_QUEUE;
250 cap->free_invariant_check_queues = END_INVARIANT_CHECK_QUEUE;
251 cap->free_trec_chunks = END_STM_CHUNK_LIST;
252 cap->free_trec_headers = NO_TREC;
253 cap->transaction_tokens = 0;
254 cap->context_switch = 0;
255 cap->pinned_object_block = NULL;
257 traceCapsetAssignCap(CAPSET_OSPROCESS_DEFAULT, i);
260 /* ---------------------------------------------------------------------------
261 * Function: initCapabilities()
263 * Purpose: set up the Capability handling. For the THREADED_RTS build,
264 * we keep a table of them, the size of which is
265 * controlled by the user via the RTS flag -N.
267 * ------------------------------------------------------------------------- */
269 initCapabilities( void )
271 /* Declare a single capability set representing the process.
272 Each capability will get added to this capset. */
273 traceCapsetCreate(CAPSET_OSPROCESS_DEFAULT, CapsetTypeOsProcess);
275 #if defined(THREADED_RTS)
279 // We can't support multiple CPUs if BaseReg is not a register
280 if (RtsFlags.ParFlags.nNodes > 1) {
281 errorBelch("warning: multiple CPUs not supported in this build, reverting to 1");
282 RtsFlags.ParFlags.nNodes = 1;
286 n_capabilities = RtsFlags.ParFlags.nNodes;
288 if (n_capabilities == 1) {
289 capabilities = &MainCapability;
290 // THREADED_RTS must work on builds that don't have a mutable
291 // BaseReg (eg. unregisterised), so in this case
292 // capabilities[0] must coincide with &MainCapability.
294 capabilities = stgMallocBytes(n_capabilities * sizeof(Capability),
298 for (i = 0; i < n_capabilities; i++) {
299 initCapability(&capabilities[i], i);
302 debugTrace(DEBUG_sched, "allocated %d capabilities", n_capabilities);
304 #else /* !THREADED_RTS */
307 capabilities = &MainCapability;
308 initCapability(&MainCapability, 0);
312 // There are no free capabilities to begin with. We will start
313 // a worker Task to each Capability, which will quickly put the
314 // Capability on the free list when it finds nothing to do.
315 last_free_capability = &capabilities[0];
318 /* ----------------------------------------------------------------------------
319 * setContextSwitches: cause all capabilities to context switch as
321 * ------------------------------------------------------------------------- */
323 void setContextSwitches(void)
326 for (i=0; i < n_capabilities; i++) {
327 contextSwitchCapability(&capabilities[i]);
331 /* ----------------------------------------------------------------------------
332 * Give a Capability to a Task. The task must currently be sleeping
333 * on its condition variable.
335 * Requires cap->lock (modifies cap->running_task).
337 * When migrating a Task, the migrater must take task->lock before
338 * modifying task->cap, to synchronise with the waking up Task.
339 * Additionally, the migrater should own the Capability (when
340 * migrating the run queue), or cap->lock (when migrating
341 * returning_workers).
343 * ------------------------------------------------------------------------- */
345 #if defined(THREADED_RTS)
347 giveCapabilityToTask (Capability *cap USED_IF_DEBUG, Task *task)
349 ASSERT_LOCK_HELD(&cap->lock);
350 ASSERT(task->cap == cap);
351 debugTrace(DEBUG_sched, "passing capability %d to %s %p",
352 cap->no, task->incall->tso ? "bound task" : "worker",
354 ACQUIRE_LOCK(&task->lock);
355 task->wakeup = rtsTrue;
356 // the wakeup flag is needed because signalCondition() doesn't
357 // flag the condition if the thread is already runniing, but we want
359 signalCondition(&task->cond);
360 RELEASE_LOCK(&task->lock);
364 /* ----------------------------------------------------------------------------
365 * Function: releaseCapability(Capability*)
367 * Purpose: Letting go of a capability. Causes a
368 * 'returning worker' thread or a 'waiting worker'
369 * to wake up, in that order.
370 * ------------------------------------------------------------------------- */
372 #if defined(THREADED_RTS)
374 releaseCapability_ (Capability* cap,
375 rtsBool always_wakeup)
379 task = cap->running_task;
381 ASSERT_PARTIAL_CAPABILITY_INVARIANTS(cap,task);
383 cap->running_task = NULL;
385 // Check to see whether a worker thread can be given
386 // the go-ahead to return the result of an external call..
387 if (cap->returning_tasks_hd != NULL) {
388 giveCapabilityToTask(cap,cap->returning_tasks_hd);
389 // The Task pops itself from the queue (see waitForReturnCapability())
393 if (waiting_for_gc == PENDING_GC_SEQ) {
394 last_free_capability = cap; // needed?
395 debugTrace(DEBUG_sched, "GC pending, set capability %d free", cap->no);
400 // If the next thread on the run queue is a bound thread,
401 // give this Capability to the appropriate Task.
402 if (!emptyRunQueue(cap) && cap->run_queue_hd->bound) {
403 // Make sure we're not about to try to wake ourselves up
404 // ASSERT(task != cap->run_queue_hd->bound);
405 // assertion is false: in schedule() we force a yield after
406 // ThreadBlocked, but the thread may be back on the run queue
408 task = cap->run_queue_hd->bound->task;
409 giveCapabilityToTask(cap,task);
413 if (!cap->spare_workers) {
414 // Create a worker thread if we don't have one. If the system
415 // is interrupted, we only create a worker task if there
416 // are threads that need to be completed. If the system is
417 // shutting down, we never create a new worker.
418 if (sched_state < SCHED_SHUTTING_DOWN || !emptyRunQueue(cap)) {
419 debugTrace(DEBUG_sched,
420 "starting new worker on capability %d", cap->no);
421 startWorkerTask(cap);
426 // If we have an unbound thread on the run queue, or if there's
427 // anything else to do, give the Capability to a worker thread.
429 !emptyRunQueue(cap) || !emptyInbox(cap) ||
430 !emptySparkPoolCap(cap) || globalWorkToDo()) {
431 if (cap->spare_workers) {
432 giveCapabilityToTask(cap,cap->spare_workers);
433 // The worker Task pops itself from the queue;
438 last_free_capability = cap;
439 debugTrace(DEBUG_sched, "freeing capability %d", cap->no);
443 releaseCapability (Capability* cap USED_IF_THREADS)
445 ACQUIRE_LOCK(&cap->lock);
446 releaseCapability_(cap, rtsFalse);
447 RELEASE_LOCK(&cap->lock);
451 releaseAndWakeupCapability (Capability* cap USED_IF_THREADS)
453 ACQUIRE_LOCK(&cap->lock);
454 releaseCapability_(cap, rtsTrue);
455 RELEASE_LOCK(&cap->lock);
459 releaseCapabilityAndQueueWorker (Capability* cap USED_IF_THREADS)
463 ACQUIRE_LOCK(&cap->lock);
465 task = cap->running_task;
467 // If the Task is stopped, we shouldn't be yielding, we should
469 ASSERT(!task->stopped);
471 // If the current task is a worker, save it on the spare_workers
472 // list of this Capability. A worker can mark itself as stopped,
473 // in which case it is not replaced on the spare_worker queue.
474 // This happens when the system is shutting down (see
475 // Schedule.c:workerStart()).
476 if (!isBoundTask(task))
478 if (cap->n_spare_workers < MAX_SPARE_WORKERS)
480 task->next = cap->spare_workers;
481 cap->spare_workers = task;
482 cap->n_spare_workers++;
486 debugTrace(DEBUG_sched, "%d spare workers already, exiting",
487 cap->n_spare_workers);
488 releaseCapability_(cap,rtsFalse);
489 // hold the lock until after workerTaskStop; c.f. scheduleWorker()
490 workerTaskStop(task);
491 RELEASE_LOCK(&cap->lock);
495 // Bound tasks just float around attached to their TSOs.
497 releaseCapability_(cap,rtsFalse);
499 RELEASE_LOCK(&cap->lock);
503 /* ----------------------------------------------------------------------------
504 * waitForReturnCapability( Task *task )
506 * Purpose: when an OS thread returns from an external call,
507 * it calls waitForReturnCapability() (via Schedule.resumeThread())
508 * to wait for permission to enter the RTS & communicate the
509 * result of the external call back to the Haskell thread that
512 * ------------------------------------------------------------------------- */
514 waitForReturnCapability (Capability **pCap, Task *task)
516 #if !defined(THREADED_RTS)
518 MainCapability.running_task = task;
519 task->cap = &MainCapability;
520 *pCap = &MainCapability;
523 Capability *cap = *pCap;
526 // Try last_free_capability first
527 cap = last_free_capability;
528 if (cap->running_task) {
530 // otherwise, search for a free capability
532 for (i = 0; i < n_capabilities; i++) {
533 if (!capabilities[i].running_task) {
534 cap = &capabilities[i];
539 // Can't find a free one, use last_free_capability.
540 cap = last_free_capability;
544 // record the Capability as the one this Task is now assocated with.
548 ASSERT(task->cap == cap);
551 ACQUIRE_LOCK(&cap->lock);
553 debugTrace(DEBUG_sched, "returning; I want capability %d", cap->no);
555 if (!cap->running_task) {
556 // It's free; just grab it
557 cap->running_task = task;
558 RELEASE_LOCK(&cap->lock);
560 newReturningTask(cap,task);
561 RELEASE_LOCK(&cap->lock);
564 ACQUIRE_LOCK(&task->lock);
565 // task->lock held, cap->lock not held
566 if (!task->wakeup) waitCondition(&task->cond, &task->lock);
568 task->wakeup = rtsFalse;
569 RELEASE_LOCK(&task->lock);
571 // now check whether we should wake up...
572 ACQUIRE_LOCK(&cap->lock);
573 if (cap->running_task == NULL) {
574 if (cap->returning_tasks_hd != task) {
575 giveCapabilityToTask(cap,cap->returning_tasks_hd);
576 RELEASE_LOCK(&cap->lock);
579 cap->running_task = task;
580 popReturningTask(cap);
581 RELEASE_LOCK(&cap->lock);
584 RELEASE_LOCK(&cap->lock);
589 ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
591 debugTrace(DEBUG_sched, "resuming capability %d", cap->no);
597 #if defined(THREADED_RTS)
598 /* ----------------------------------------------------------------------------
600 * ------------------------------------------------------------------------- */
603 yieldCapability (Capability** pCap, Task *task)
605 Capability *cap = *pCap;
607 if (waiting_for_gc == PENDING_GC_PAR) {
608 traceEventGcStart(cap);
610 traceEventGcEnd(cap);
614 debugTrace(DEBUG_sched, "giving up capability %d", cap->no);
616 // We must now release the capability and wait to be woken up
618 task->wakeup = rtsFalse;
619 releaseCapabilityAndQueueWorker(cap);
622 ACQUIRE_LOCK(&task->lock);
623 // task->lock held, cap->lock not held
624 if (!task->wakeup) waitCondition(&task->cond, &task->lock);
626 task->wakeup = rtsFalse;
627 RELEASE_LOCK(&task->lock);
629 debugTrace(DEBUG_sched, "woken up on capability %d", cap->no);
631 ACQUIRE_LOCK(&cap->lock);
632 if (cap->running_task != NULL) {
633 debugTrace(DEBUG_sched,
634 "capability %d is owned by another task", cap->no);
635 RELEASE_LOCK(&cap->lock);
639 if (task->incall->tso == NULL) {
640 ASSERT(cap->spare_workers != NULL);
641 // if we're not at the front of the queue, release it
642 // again. This is unlikely to happen.
643 if (cap->spare_workers != task) {
644 giveCapabilityToTask(cap,cap->spare_workers);
645 RELEASE_LOCK(&cap->lock);
648 cap->spare_workers = task->next;
650 cap->n_spare_workers--;
652 cap->running_task = task;
653 RELEASE_LOCK(&cap->lock);
657 debugTrace(DEBUG_sched, "resuming capability %d", cap->no);
658 ASSERT(cap->running_task == task);
662 ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
667 /* ----------------------------------------------------------------------------
670 * If a Capability is currently idle, wake up a Task on it. Used to
671 * get every Capability into the GC.
672 * ------------------------------------------------------------------------- */
675 prodCapability (Capability *cap, Task *task)
677 ACQUIRE_LOCK(&cap->lock);
678 if (!cap->running_task) {
679 cap->running_task = task;
680 releaseCapability_(cap,rtsTrue);
682 RELEASE_LOCK(&cap->lock);
685 /* ----------------------------------------------------------------------------
688 * Attempt to gain control of a Capability if it is free.
690 * ------------------------------------------------------------------------- */
693 tryGrabCapability (Capability *cap, Task *task)
695 if (cap->running_task != NULL) return rtsFalse;
696 ACQUIRE_LOCK(&cap->lock);
697 if (cap->running_task != NULL) {
698 RELEASE_LOCK(&cap->lock);
702 cap->running_task = task;
703 RELEASE_LOCK(&cap->lock);
708 #endif /* THREADED_RTS */
710 /* ----------------------------------------------------------------------------
713 * At shutdown time, we want to let everything exit as cleanly as
714 * possible. For each capability, we let its run queue drain, and
715 * allow the workers to stop.
717 * This function should be called when interrupted and
718 * shutting_down_scheduler = rtsTrue, thus any worker that wakes up
719 * will exit the scheduler and call taskStop(), and any bound thread
720 * that wakes up will return to its caller. Runnable threads are
723 * ------------------------------------------------------------------------- */
726 shutdownCapability (Capability *cap,
727 Task *task USED_IF_THREADS,
728 rtsBool safe USED_IF_THREADS)
730 #if defined(THREADED_RTS)
735 // Loop indefinitely until all the workers have exited and there
736 // are no Haskell threads left. We used to bail out after 50
737 // iterations of this loop, but that occasionally left a worker
738 // running which caused problems later (the closeMutex() below
739 // isn't safe, for one thing).
741 for (i = 0; /* i < 50 */; i++) {
742 ASSERT(sched_state == SCHED_SHUTTING_DOWN);
744 debugTrace(DEBUG_sched,
745 "shutting down capability %d, attempt %d", cap->no, i);
746 ACQUIRE_LOCK(&cap->lock);
747 if (cap->running_task) {
748 RELEASE_LOCK(&cap->lock);
749 debugTrace(DEBUG_sched, "not owner, yielding");
753 cap->running_task = task;
755 if (cap->spare_workers) {
756 // Look for workers that have died without removing
757 // themselves from the list; this could happen if the OS
758 // summarily killed the thread, for example. This
759 // actually happens on Windows when the system is
760 // terminating the program, and the RTS is running in a
764 for (t = cap->spare_workers; t != NULL; t = t->next) {
765 if (!osThreadIsAlive(t->id)) {
766 debugTrace(DEBUG_sched,
767 "worker thread %p has died unexpectedly", (void *)t->id);
768 cap->n_spare_workers--;
770 cap->spare_workers = t->next;
772 prev->next = t->next;
779 if (!emptyRunQueue(cap) || cap->spare_workers) {
780 debugTrace(DEBUG_sched,
781 "runnable threads or workers still alive, yielding");
782 releaseCapability_(cap,rtsFalse); // this will wake up a worker
783 RELEASE_LOCK(&cap->lock);
788 // If "safe", then busy-wait for any threads currently doing
789 // foreign calls. If we're about to unload this DLL, for
790 // example, we need to be sure that there are no OS threads
791 // that will try to return to code that has been unloaded.
792 // We can be a bit more relaxed when this is a standalone
793 // program that is about to terminate, and let safe=false.
794 if (cap->suspended_ccalls && safe) {
795 debugTrace(DEBUG_sched,
796 "thread(s) are involved in foreign calls, yielding");
797 cap->running_task = NULL;
798 RELEASE_LOCK(&cap->lock);
799 // The IO manager thread might have been slow to start up,
800 // so the first attempt to kill it might not have
801 // succeeded. Just in case, try again - the kill message
802 // will only be sent once.
804 // To reproduce this deadlock: run ffi002(threaded1)
805 // repeatedly on a loaded machine.
811 traceEventShutdown(cap);
812 RELEASE_LOCK(&cap->lock);
815 // we now have the Capability, its run queue and spare workers
816 // list are both empty.
818 // ToDo: we can't drop this mutex, because there might still be
819 // threads performing foreign calls that will eventually try to
820 // return via resumeThread() and attempt to grab cap->lock.
821 // closeMutex(&cap->lock);
823 #endif /* THREADED_RTS */
825 traceCapsetRemoveCap(CAPSET_OSPROCESS_DEFAULT, cap->no);
829 shutdownCapabilities(Task *task, rtsBool safe)
832 for (i=0; i < n_capabilities; i++) {
833 ASSERT(task->incall->tso == NULL);
834 shutdownCapability(&capabilities[i], task, safe);
836 traceCapsetDelete(CAPSET_OSPROCESS_DEFAULT);
840 freeCapability (Capability *cap)
842 stgFree(cap->mut_lists);
843 stgFree(cap->saved_mut_lists);
844 #if defined(THREADED_RTS)
845 freeSparkPool(cap->sparks);
850 freeCapabilities (void)
852 #if defined(THREADED_RTS)
854 for (i=0; i < n_capabilities; i++) {
855 freeCapability(&capabilities[i]);
858 freeCapability(&MainCapability);
862 /* ---------------------------------------------------------------------------
863 Mark everything directly reachable from the Capabilities. When
864 using multiple GC threads, each GC thread marks all Capabilities
865 for which (c `mod` n == 0), for Capability c and thread n.
866 ------------------------------------------------------------------------ */
869 markCapability (evac_fn evac, void *user, Capability *cap,
870 rtsBool no_mark_sparks USED_IF_THREADS)
874 // Each GC thread is responsible for following roots from the
875 // Capability of the same number. There will usually be the same
876 // or fewer Capabilities as GC threads, but just in case there
877 // are more, we mark every Capability whose number is the GC
878 // thread's index plus a multiple of the number of GC threads.
879 evac(user, (StgClosure **)(void *)&cap->run_queue_hd);
880 evac(user, (StgClosure **)(void *)&cap->run_queue_tl);
881 #if defined(THREADED_RTS)
882 evac(user, (StgClosure **)(void *)&cap->inbox);
884 for (incall = cap->suspended_ccalls; incall != NULL;
885 incall=incall->next) {
886 evac(user, (StgClosure **)(void *)&incall->suspended_tso);
889 #if defined(THREADED_RTS)
890 if (!no_mark_sparks) {
891 traverseSparkQueue (evac, user, cap);
895 // Free STM structures for this Capability
900 markCapabilities (evac_fn evac, void *user)
903 for (n = 0; n < n_capabilities; n++) {
904 markCapability(evac, user, &capabilities[n], rtsFalse);