* --------------------------------------------------------------------------*/
#include "PosixSource.h"
#include "Rts.h"
-#include "Schedule.h"
#include "RtsUtils.h"
+#include "OSThreads.h"
#include "Capability.h"
+#include "Schedule.h" /* to get at EMPTY_RUN_QUEUE() */
#if !defined(SMP)
Capability MainCapability; /* for non-SMP, we have one global capability */
* the task(s) that enter the Scheduler will check to see whether
* there are one or more worker threads blocked waiting on
* returning_worker_cond.
+ */
+static nat rts_n_waiting_workers = 0;
+
+/* thread_ready_cond: when signalled, a thread has become runnable for a
+ * task to execute.
+ *
+ * In the non-SMP case, it also implies that the thread that is woken up has
+ * exclusive access to the RTS and all its data structures (that are not
+ * locked by the Scheduler's mutex).
+ *
+ * thread_ready_cond is signalled whenever COND_NO_THREADS_READY doesn't hold.
*
- * Locks needed: sched_mutex
*/
-nat rts_n_waiting_workers = 0;
+Condition thread_ready_cond = INIT_COND_VAR;
+#if 0
+/* For documentation purposes only */
+#define COND_NO_THREADS_READY() (noCapabilities() || EMPTY_RUN_QUEUE())
#endif
+/*
+ * To be able to make an informed decision about whether or not
+ * to create a new task when making an external call, keep track of
+ * the number of tasks currently blocked waiting on thread_ready_cond.
+ * (if > 0 => no need for a new task, just unblock an existing one).
+ *
+ * waitForWork() takes care of keeping it up-to-date; Task.startTask()
+ * uses its current value.
+ */
+nat rts_n_waiting_tasks = 0;
+#endif
+
+/* -----------------------------------------------------------------------------
+ Initialisation
+ -------------------------------------------------------------------------- */
static
void
initCapability( Capability *cap )
{
#if defined(RTS_SUPPORTS_THREADS)
initCondition(&returning_worker_cond);
+ initCondition(&thread_ready_cond);
#endif
#if defined(SMP)
return;
}
-/* Free capability list.
- * Locks required: sched_mutex.
- */
#if defined(SMP)
+/* Free capability list. */
static Capability *free_capabilities; /* Available capabilities for running threads */
#endif
+/* -----------------------------------------------------------------------------
+ Acquiring capabilities
+ -------------------------------------------------------------------------- */
+
/*
* Function: grabCapability(Capability**)
*
* remove one from the free capabilities list (which
* may just have one entry). In threaded builds, worker
* threads are prevented from doing so willy-nilly
- * through the use of the sched_mutex lock along with
- * condition variables thread_ready_cond and
+ * via the condition variables thread_ready_cond and
* returning_worker_cond.
*
- * Pre-condition: sched_mutex is held (in threaded builds only).
- *
*/
void grabCapability(Capability** cap)
{
/*
* Function: releaseCapability(Capability*)
*
- * Purpose: Letting go of a capability.
+ * Purpose: Letting go of a capability. Causes a
+ * 'returning worker' thread or a 'waiting worker'
+ * to wake up, in that order.
*
- * Pre-condition: sched_mutex is assumed held by current thread.
- * Post-condition:
*/
void releaseCapability(Capability* cap
#if !defined(SMP)
* value of rts_n_waiting_workers. If > 0, the worker thread
* will yield its capability to let a returning worker thread
* proceed with returning its result -- this is done via
- * yieldCapability().
+ * yieldToReturningWorker().
* - the worker thread that yielded its capability then tries
* to re-grab a capability and re-enter the Scheduler.
*/
* result of the ext. call back to the Haskell thread that
* made it.
*
- * Pre-condition: sched_mutex isn't held.
- * Post-condition: sched_mutex is held and a capability has
+ * Pre-condition: pMutex isn't held.
+ * Post-condition: pMutex is held and a capability has
* been assigned to the worker thread.
*/
void
-grabReturnCapability(Capability** pCap)
+grabReturnCapability(Mutex* pMutex, Capability** pCap)
{
IF_DEBUG(scheduler,
- fprintf(stderr,"worker (%ld): returning, waiting for sched. lock.\n", osThreadId()));
- ACQUIRE_LOCK(&sched_mutex);
+ fprintf(stderr,"worker (%ld): returning, waiting for lock.\n", osThreadId()));
+ ACQUIRE_LOCK(pMutex);
rts_n_waiting_workers++;
IF_DEBUG(scheduler,
fprintf(stderr,"worker (%ld): returning; workers waiting: %d\n",
osThreadId(), rts_n_waiting_workers));
while ( noCapabilities() ) {
- waitCondition(&returning_worker_cond, &sched_mutex);
+ waitCondition(&returning_worker_cond, pMutex);
}
grabCapability(pCap);
return;
}
+
+/* -----------------------------------------------------------------------------
+ Yielding/waiting for capabilities
+ -------------------------------------------------------------------------- */
+
/*
- * Function: yieldCapability(Capability**)
+ * Function: yieldToReturningWorker(Mutex*,Capability*)
*
* Purpose: when, upon entry to the Scheduler, an OS worker thread
* spots that one or more threads are blocked waiting for
* permission to return back their result, it gives up
* its Capability.
*
- * Pre-condition: sched_mutex is held and the thread possesses
+ * Pre-condition: pMutex is assumed held and the thread possesses
* a Capability.
- * Post-condition: sched_mutex isn't held and the Capability has
+ * Post-condition: pMutex isn't held and the Capability has
* been given back.
*/
void
-yieldCapability(Capability* cap)
+yieldToReturningWorker(Mutex* pMutex, Capability* cap)
{
+ if ( rts_n_waiting_workers > 0 && noCapabilities() ) {
IF_DEBUG(scheduler,
fprintf(stderr,"worker thread (%ld): giving up RTS token\n", osThreadId()));
releaseCapability(cap);
- RELEASE_LOCK(&sched_mutex);
+ RELEASE_LOCK(pMutex);
yieldThread();
- /* At this point, sched_mutex has been given up & we've
+ /* At this point, pMutex has been given up & we've
* forced a thread context switch. Guaranteed to be
* enough for the signalled worker thread to race
- * ahead?
+ * ahead of us?
*/
- return;
+
+ /* Re-grab the mutex */
+ ACQUIRE_LOCK(pMutex);
+ }
+ return;
}
+
+/*
+ * Function: waitForWorkCapability(Mutex*, Capability**, rtsBool)
+ *
+ * Purpose: wait for a Capability to become available. In
+ * the process of doing so, updates the number
+ * of tasks currently blocked waiting for a capability/more
+ * work. That counter is used when deciding whether or
+ * not to create a new worker thread when an external
+ * call is made.
+ *
+ * Pre-condition: pMutex is held.
+ */
+void
+waitForWorkCapability(Mutex* pMutex, Capability** pCap, rtsBool runnable)
+{
+ while ( noCapabilities() || (runnable && EMPTY_RUN_QUEUE()) ) {
+ rts_n_waiting_tasks++;
+ waitCondition(&thread_ready_cond, pMutex);
+ rts_n_waiting_tasks--;
+ }
+ grabCapability(pCap);
+ return;
+}
#endif /* RTS_SUPPORTS_THREADS */
#if defined(SMP)
* holding 'n' Capabilities. Only for SMP, since
* it is the only build that supports multiple
* capabilities within the RTS.
- *
- * Pre-condition: sched_mutex is held.
- *
*/
static void
initCapabilities_(nat n)
extern nat rts_n_free_capabilities;
extern nat rts_n_waiting_workers;
-extern void grabReturnCapability(Capability** pCap);
-extern void yieldCapability(Capability* cap);
+extern void grabReturnCapability(Mutex* pMutex, Capability** pCap);
+extern void yieldToReturningWorker(Mutex* pMutex, Capability* cap);
+extern void waitForWorkCapability(Mutex* pMutex, Capability** pCap, rtsBool runnable);
static inline nat getFreeCapabilities (void)
{
/* ---------------------------------------------------------------------------
- * $Id: Schedule.c,v 1.123 2002/02/14 07:52:05 sof Exp $
+ * $Id: Schedule.c,v 1.124 2002/02/15 07:50:36 sof Exp $
*
* (c) The GHC Team, 1998-2000
*
Mutex sched_mutex = INIT_MUTEX_VAR;
Mutex term_mutex = INIT_MUTEX_VAR;
-
-
-
-/* thread_ready_cond: when signalled, a thread has become runnable for a
- * task to execute.
- *
- * In the non-SMP case, it also implies that the thread that is woken up has
- * exclusive access to the RTS and all its data structures (that are not
- * under sched_mutex's control).
- *
- * thread_ready_cond is signalled whenever COND_NO_THREADS_READY doesn't hold.
- *
- */
-Condition thread_ready_cond = INIT_COND_VAR;
-#if 0
-/* For documentation purposes only */
-#define COND_NO_THREADS_READY() (noCapabilities() || EMPTY_RUN_QUEUE())
-#endif
-
-/*
- * To be able to make an informed decision about whether or not
- * to create a new task when making an external call, keep track of
- * the number of tasks currently blocked waiting on thread_ready_cond.
- * (if > 0 => no need for a new task, just unblock an existing one).
- *
- * waitForWork() takes care of keeping it up-to-date; Task.startTask()
- * uses its current value.
- */
-nat rts_n_waiting_tasks = 0;
-
-static void waitForWork(void);
-
# if defined(SMP)
static Condition gc_pending_cond = INIT_COND_VAR;
nat await_death;
# endif
#endif
rtsBool was_interrupted = rtsFalse;
-
-#if defined(RTS_SUPPORTS_THREADS)
-schedule_start:
-#endif
-#if defined(RTS_SUPPORTS_THREADS)
ACQUIRE_LOCK(&sched_mutex);
-#endif
#if defined(RTS_SUPPORTS_THREADS)
- /* ToDo: consider SMP support */
- if ( rts_n_waiting_workers > 0 && noCapabilities() ) {
- /* (At least) one native thread is waiting to
- * deposit the result of an external call. So,
- * be nice and hand over our capability.
- */
- yieldCapability(cap);
- /* Lost our sched_mutex lock, try to re-enter the scheduler. */
- goto schedule_start;
- }
-#endif
+ /* Check to see whether there are any worker threads
+ waiting to deposit external call results. If so,
+ yield our capability */
+ yieldToReturningWorker(&sched_mutex, cap);
-#if defined(RTS_SUPPORTS_THREADS)
- while ( noCapabilities() ) {
- waitForWork();
- }
+ waitForWorkCapability(&sched_mutex, &cap, rtsFalse);
#endif
#if defined(GRAN)
-
/* set up first event to get things going */
/* ToDo: assign costs for system setup and init MainTSO ! */
new_event(CurrentProc, CurrentProc, CurrentTime[CurrentProc],
if ( EMPTY_RUN_QUEUE() ) {
/* Give up our capability */
releaseCapability(cap);
- while ( noCapabilities() || EMPTY_RUN_QUEUE() ) {
- IF_DEBUG(scheduler, sched_belch("thread %d: waiting for work", osThreadId()));
- waitForWork();
- IF_DEBUG(scheduler, sched_belch("thread %d: work now available %d %d", osThreadId(), getFreeCapabilities(),EMPTY_RUN_QUEUE()));
+ IF_DEBUG(scheduler, sched_belch("thread %d: waiting for work", osThreadId()));
+ waitForWorkCapability(&sched_mutex, &cap, rtsTrue);
+ IF_DEBUG(scheduler, sched_belch("thread %d: work now available", osThreadId()));
+#if 0
+ while ( EMPTY_RUN_QUEUE() ) {
+ waitForWorkCapability(&sched_mutex, &cap);
+ IF_DEBUG(scheduler, sched_belch("thread %d: work now available", osThreadId()));
}
+#endif
}
#endif
#if defined(GRAN)
-
if (RtsFlags.GranFlags.Light)
GranSimLight_enter_system(event, &ActiveTSO); // adjust ActiveTSO etc
belch("--=^ %d threads, %d sparks on [%#x]",
run_queue_len(), spark_queue_len(pool), CURRENT_PROC));
-#if 1
+# if 1
if (0 && RtsFlags.ParFlags.ParStats.Full &&
t && LastTSO && t->id != LastTSO->id &&
LastTSO->why_blocked == NotBlocked &&
emitSchedule = rtsFalse;
}
-#endif
+# endif
#else /* !GRAN && !PAR */
/* grab a thread from the run queue */
}
#endif
+ if (ready_to_gc
#ifdef SMP
- if (ready_to_gc && allFreeCapabilities() )
-#else
- if (ready_to_gc)
+ && allFreeCapabilities()
#endif
- {
+ ) {
/* everybody back, start the GC.
* Could do it in this thread, or signal a condition var
* to do it in another thread. Either way, we need to
for one (i.e., if there's only one Concurrent Haskell thread alive,
there's no need to create a new task).
*/
- IF_DEBUG(scheduler, sched_belch("worker thread (%d): leaving RTS\n", tok));
+ IF_DEBUG(scheduler, sched_belch("worker thread (%d): leaving RTS", tok));
startTask(taskStart);
#endif
Capability *cap;
#if defined(RTS_SUPPORTS_THREADS)
- /* Wait for permission to re-enter the RTS with the result.. */
- grabReturnCapability(&cap);
+ /* Wait for permission to re-enter the RTS with the result. */
+ grabReturnCapability(&sched_mutex, &cap);
#else
grabCapability(&cap);
#endif
}
-#if defined(RTS_SUPPORTS_THREADS)
-static void
-waitForWork()
-{
- rts_n_waiting_tasks++;
- waitCondition(&thread_ready_cond, &sched_mutex);
- rts_n_waiting_tasks--;
- return;
-}
-#endif
-
-
/* ---------------------------------------------------------------------------
* Static functions
* ------------------------------------------------------------------------ */
* on this thread's stack before the scheduler is invoked.
* ------------------------------------------------------------------------ */
+static void scheduleThread_ (StgTSO* tso, rtsBool createTask);
+
void
scheduleThread_(StgTSO *tso
-#if defined(THREADED_RTS)
, rtsBool createTask
+#if !defined(THREADED_RTS)
+ STG_UNUSED
#endif
)
{
void scheduleThread(StgTSO* tso)
{
-#if defined(THREADED_RTS)
+ return scheduleThread_(tso, rtsFalse);
+}
+
+void scheduleExtThread(StgTSO* tso)
+{
return scheduleThread_(tso, rtsTrue);
-#else
- return scheduleThread_(tso);
-#endif
}
/* ---------------------------------------------------------------------------
//@subsection Index
//@index
-//* MainRegTable:: @cindex\s-+MainRegTable
//* StgMainThread:: @cindex\s-+StgMainThread
//* awaken_blocked_queue:: @cindex\s-+awaken_blocked_queue
//* blocked_queue_hd:: @cindex\s-+blocked_queue_hd
//* schedule:: @cindex\s-+schedule
//* take_off_run_queue:: @cindex\s-+take_off_run_queue
//* term_mutex:: @cindex\s-+term_mutex
-//* thread_ready_cond:: @cindex\s-+thread_ready_cond
//@end index
/* -----------------------------------------------------------------------------
- * $Id: Schedule.h,v 1.28 2002/02/13 08:48:07 sof Exp $
+ * $Id: Schedule.h,v 1.29 2002/02/15 07:50:37 sof Exp $
*
* (c) The GHC Team 1998-1999
*
, rtsBool blockWaiting
#endif
);
-extern void scheduleThread_(StgTSO *tso
-#if defined(THREADED_RTS)
- , rtsBool createTask
-#endif
- );
extern SchedulerStatus rts_mainEvalIO(HaskellObj p, /*out*/HaskellObj *ret);
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