/* ---------------------------------------------------------------------------
- * $Id: Schedule.c,v 1.118 2002/02/06 01:29:27 sof Exp $
+ * $Id: Schedule.c,v 1.127 2002/02/15 17:49:23 sof Exp $
*
* (c) The GHC Team, 1998-2000
*
/* rtsTime TimeOfNextEvent, EndOfTimeSlice; now in GranSim.c */
/*
- In GranSim we have a runable and a blocked queue for each processor.
+ In GranSim we have a runnable and a blocked queue for each processor.
In order to minimise code changes new arrays run_queue_hds/tls
are created. run_queue_hd is then a short cut (macro) for
run_queue_hds[CurrentProc] (see GranSim.h).
*/
StgTSO *all_threads;
-/* Threads suspended in _ccall_GC.
+/* When a thread performs a safe C call (_ccall_GC, using old
+ * terminology), it gets put on the suspended_ccalling_threads
+ * list. Used by the garbage collector.
*/
static StgTSO *suspended_ccalling_threads;
*/
Mutex sched_mutex = INIT_MUTEX_VAR;
Mutex term_mutex = INIT_MUTEX_VAR;
-#if defined(THREADED_RTS)
-/*
- * The rts_mutex is the 'big lock' that the active native
- * thread within the RTS holds while executing code.
- * It is given up when the thread makes a transition out of
- * the RTS (e.g., to perform an external C call), hopefully
- * for another thread to take over its chores and enter
- * the RTS.
- *
- */
-Mutex rts_mutex = INIT_MUTEX_VAR;
-/*
- * When a native thread has completed executing an external
- * call, it needs to communicate the result back to the
- * (Haskell) thread that made the call. Do this as follows:
- *
- * - in resumeThread(), the thread increments the counter
- * threads_waiting, and then blocks on the 'big' RTS lock.
- * - upon entry to the scheduler, the thread that's currently
- * holding the RTS lock checks threads_waiting. If there
- * are native threads waiting, it gives up its RTS lock
- * and tries to re-grab the RTS lock [perhaps after having
- * waited for a bit..?]
- * - care must be taken to deal with the case where more than
- * one external thread are waiting on the lock. [ToDo: more]
- *
- */
-
-static nat threads_waiting = 0;
-/*
- * thread_ready_aux_mutex is used to handle the scenario where the
- * the RTS executing thread runs out of work, but there are
- * active external threads. The RTS executing thread gives up
- * its RTS mutex, and blocks waiting for the thread_ready_cond.
- * Unfortunately, a condition variable needs to be associated
- * with a mutex in pthreads, so rts_thread_waiting_mutex is
- * used for just this purpose.
- *
- */
-Mutex thread_ready_aux_mutex = INIT_MUTEX_VAR;
-#endif
-
-
-/* thread_ready_cond: when signalled, a thread has
- * become runnable. When used?
- */
-Condition thread_ready_cond = INIT_COND_VAR;
-Condition gc_pending_cond = INIT_COND_VAR;
+# if defined(SMP)
+static Condition gc_pending_cond = INIT_COND_VAR;
nat await_death;
-#endif
+# endif
+
+#endif /* RTS_SUPPORTS_THREADS */
#if defined(PAR)
StgTSO *LastTSO;
static void
taskStart(void)
{
- /* threads start up using 'taskStart', so make them
- them grab the RTS lock. */
-#if defined(THREADED_RTS)
- ACQUIRE_LOCK(&rts_mutex);
- taskNotAvailable();
-#endif
schedule();
}
#endif
rtsBool was_interrupted = rtsFalse;
ACQUIRE_LOCK(&sched_mutex);
-
-#if defined(THREADED_RTS)
- /* ToDo: consider SMP support */
- if (threads_waiting > 0) {
- /* (At least) one native thread is waiting to
- * deposit the result of an external call. So,
- * give up our RTS executing privileges and let
- * one of them continue.
- *
- */
- taskAvailable();
- RELEASE_LOCK(&sched_mutex);
- IF_DEBUG(scheduler, sched_belch("worker thread (%d): giving up RTS token (threads_waiting=%d)\n", osThreadId(), threads_waiting));
- RELEASE_LOCK(&rts_mutex);
- /* ToDo: come up with mechanism that guarantees that
- * the main thread doesn't loop here.
- */
- yieldThread();
- /* ToDo: longjmp() */
- taskStart();
- }
+
+#if defined(RTS_SUPPORTS_THREADS)
+ /* Check to see whether there are any worker threads
+ waiting to deposit external call results. If so,
+ yield our capability */
+ yieldToReturningWorker(&sched_mutex, cap);
+
+ 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],
* ToDo: what if another client comes along & requests another
* main thread?
*/
- if (blocked_queue_hd != END_TSO_QUEUE || sleeping_queue != END_TSO_QUEUE) {
- awaitEvent(
- (run_queue_hd == END_TSO_QUEUE)
+ if ( !EMPTY_QUEUE(blocked_queue_hd) || !EMPTY_QUEUE(sleeping_queue) ) {
+ awaitEvent( EMPTY_RUN_QUEUE()
#if defined(SMP)
&& allFreeCapabilities()
#endif
* inform all the main threads.
*/
#ifndef PAR
- if (blocked_queue_hd == END_TSO_QUEUE
- && run_queue_hd == END_TSO_QUEUE
- && sleeping_queue == END_TSO_QUEUE
-#if defined(SMP)
+ if ( EMPTY_RUN_QUEUE()
+ && EMPTY_QUEUE(blocked_queue_hd)
+ && EMPTY_QUEUE(sleeping_queue)
+#if defined(RTS_SUPPORTS_THREADS)
+ && EMPTY_QUEUE(suspended_ccalling_threads)
+#endif
+#ifdef SMP
&& allFreeCapabilities()
-#elif defined(THREADED_RTS)
- && suspended_ccalling_threads == END_TSO_QUEUE
#endif
)
{
IF_DEBUG(scheduler, sched_belch("deadlocked, forcing major GC..."));
+#if defined(THREADED_RTS)
+ /* and SMP mode ..? */
+ releaseCapability(cap);
+#endif
RELEASE_LOCK(&sched_mutex);
GarbageCollect(GetRoots,rtsTrue);
ACQUIRE_LOCK(&sched_mutex);
- IF_DEBUG(scheduler, sched_belch("GC done."));
- if (blocked_queue_hd == END_TSO_QUEUE
- && run_queue_hd == END_TSO_QUEUE
- && sleeping_queue == END_TSO_QUEUE) {
+ if ( EMPTY_QUEUE(blocked_queue_hd)
+ && EMPTY_RUN_QUEUE()
+ && EMPTY_QUEUE(sleeping_queue) ) {
IF_DEBUG(scheduler, sched_belch("still deadlocked, checking for black holes..."));
detectBlackHoles();
* build, send *all* main threads the deadlock exception,
* since none of them can make progress).
*/
- if (run_queue_hd == END_TSO_QUEUE) {
+ if ( EMPTY_RUN_QUEUE() ) {
StgMainThread *m;
#if defined(RTS_SUPPORTS_THREADS)
for (m = main_threads; m != NULL; m = m->link) {
#endif
}
#if defined(RTS_SUPPORTS_THREADS)
- if ( run_queue_hd == END_TSO_QUEUE ) {
- IF_DEBUG(scheduler, sched_belch("all done, it seems...shut down."));
+ /* ToDo: revisit conditions (and mechanism) for shutting
+ down a multi-threaded world */
+ if ( EMPTY_RUN_QUEUE() ) {
+ IF_DEBUG(scheduler, sched_belch("all done, i think...shutting down."));
shutdownHaskellAndExit(0);
-
}
#endif
- ASSERT( run_queue_hd != END_TSO_QUEUE );
+ ASSERT( !EMPTY_RUN_QUEUE() );
}
}
#elif defined(PAR)
}
#endif
-#if defined(SMP)
+#if defined(RTS_SUPPORTS_THREADS)
/* block until we've got a thread on the run queue and a free
* capability.
+ *
*/
- while ( run_queue_hd == END_TSO_QUEUE
- || noFreeCapabilities()
- ) {
- IF_DEBUG(scheduler, sched_belch("waiting for work"));
- waitCondition( &thread_ready_cond, &sched_mutex );
- IF_DEBUG(scheduler, sched_belch("work now available"));
+ if ( EMPTY_RUN_QUEUE() ) {
+ /* Give up our capability */
+ releaseCapability(cap);
+ 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
}
-#elif defined(THREADED_RTS)
- if ( run_queue_hd == END_TSO_QUEUE ) {
- /* no work available, wait for external calls to complete. */
- IF_DEBUG(scheduler, sched_belch("worker thread (%d): waiting for external thread to complete..", osThreadId()));
- taskAvailable();
- RELEASE_LOCK(&sched_mutex);
- RELEASE_LOCK(&rts_mutex);
-
- /* Sigh - need to have a mutex locked in order to wait on the
- condition variable. */
- ACQUIRE_LOCK(&thread_ready_aux_mutex);
- waitCondition(&thread_ready_cond, &thread_ready_aux_mutex);
- RELEASE_LOCK(&thread_ready_aux_mutex);
-
- IF_DEBUG(scheduler, sched_belch("worker thread (%d): re-awakened from no-work slumber..\n", osThreadId()));
- /* ToDo: longjmp() */
- taskStart();
- }
#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
- */
+ /* grab a thread from the run queue */
ASSERT(run_queue_hd != END_TSO_QUEUE);
t = POP_RUN_QUEUE();
// Sanity check the thread we're about to run. This can be
barf("schedule: invalid thread return code %d", (int)ret);
}
-#ifdef SMP
+#if defined(RTS_SUPPORTS_THREADS)
+ /* I don't understand what this re-grab is doing -- sof */
grabCapability(&cap);
#endif
}
#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
cap->r.rCurrentTSO->link = suspended_ccalling_threads;
suspended_ccalling_threads = cap->r.rCurrentTSO;
+#if defined(RTS_SUPPORTS_THREADS)
+ cap->r.rCurrentTSO->why_blocked = BlockedOnCCall;
+#endif
+
/* Use the thread ID as the token; it should be unique */
tok = cap->r.rCurrentTSO->id;
/* Hand back capability */
- releaseCapability(&cap);
+ releaseCapability(cap);
#if defined(RTS_SUPPORTS_THREADS) && !defined(SMP)
/* Preparing to leave the RTS, so ensure there's a native thread/task
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
-
+
+ THREAD_RUNNABLE();
RELEASE_LOCK(&sched_mutex);
- RELEASE_LOCK(&rts_mutex);
return tok;
}
StgTSO *tso, **prev;
Capability *cap;
-#if defined(THREADED_RTS)
- IF_DEBUG(scheduler, sched_belch("thread %d returning, waiting for sched. lock.\n", tok));
- ACQUIRE_LOCK(&sched_mutex);
- threads_waiting++;
- IF_DEBUG(scheduler, sched_belch("thread %d returning, threads waiting: %d.\n", tok, threads_waiting));
- RELEASE_LOCK(&sched_mutex);
-
- IF_DEBUG(scheduler, sched_belch("thread %d waiting for RTS lock...\n", tok));
- ACQUIRE_LOCK(&rts_mutex);
- threads_waiting--;
- taskNotAvailable();
- IF_DEBUG(scheduler, sched_belch("thread %d acquired RTS lock...\n", tok));
-#endif
-
-#if defined(THREADED_RTS)
- /* Free up any RTS-blocked threads. */
- broadcastCondition(&thread_ready_cond);
+#if defined(RTS_SUPPORTS_THREADS)
+ /* Wait for permission to re-enter the RTS with the result. */
+ grabReturnCapability(&sched_mutex, &cap);
+#else
+ grabCapability(&cap);
#endif
/* Remove the thread off of the suspended list */
barf("resumeThread: thread not found");
}
tso->link = END_TSO_QUEUE;
+ /* Reset blocking status */
+ tso->why_blocked = NotBlocked;
-#if defined(SMP)
- while ( noFreeCapabilities() ) {
- IF_DEBUG(scheduler, sched_belch("waiting to resume"));
- waitCondition(&thread_ready_cond, &sched_mutex);
- IF_DEBUG(scheduler, sched_belch("resuming thread %d", tso->id));
- }
-#endif
-
- grabCapability(&cap);
+ RELEASE_LOCK(&sched_mutex);
cap->r.rCurrentTSO = tso;
-
return &cap->r;
}
* on this thread's stack before the scheduler is invoked.
* ------------------------------------------------------------------------ */
+static void scheduleThread_ (StgTSO* tso, rtsBool createTask);
+
void
-scheduleThread(StgTSO *tso)
+scheduleThread_(StgTSO *tso
+ , rtsBool createTask
+#if !defined(THREADED_RTS)
+ STG_UNUSED
+#endif
+ )
{
ACQUIRE_LOCK(&sched_mutex);
* soon as we release the scheduler lock below.
*/
PUSH_ON_RUN_QUEUE(tso);
+#if defined(THREADED_RTS)
+ /* If main() is scheduling a thread, don't bother creating a
+ * new task.
+ */
+ if ( createTask ) {
+ startTask(taskStart);
+ }
+#endif
THREAD_RUNNABLE();
#if 0
RELEASE_LOCK(&sched_mutex);
}
+void scheduleThread(StgTSO* tso)
+{
+ return scheduleThread_(tso, rtsFalse);
+}
+
+void scheduleExtThread(StgTSO* tso)
+{
+ return scheduleThread_(tso, rtsTrue);
+}
+
/* ---------------------------------------------------------------------------
* initScheduler()
*
#if defined(RTS_SUPPORTS_THREADS)
/* Initialise the mutex and condition variables used by
* the scheduler. */
- initMutex(&rts_mutex);
initMutex(&sched_mutex);
initMutex(&term_mutex);
-#if defined(THREADED_RTS)
- initMutex(&thread_ready_aux_mutex);
+
+ initCondition(&thread_ready_cond);
#endif
- initCondition(&thread_ready_cond);
+#if defined(SMP)
initCondition(&gc_pending_cond);
#endif
-#if defined(THREADED_RTS)
- /* Grab big lock */
- ACQUIRE_LOCK(&rts_mutex);
- IF_DEBUG(scheduler,
- sched_belch("worker thread (%d): acquired RTS lock\n", osThreadId()));
+#if defined(RTS_SUPPORTS_THREADS)
+ ACQUIRE_LOCK(&sched_mutex);
#endif
/* Install the SIGHUP handler */
-#ifdef SMP
+#if defined(SMP)
{
struct sigaction action,oact;
#if /* defined(SMP) ||*/ defined(PAR)
initSparkPools();
#endif
+
+#if defined(RTS_SUPPORTS_THREADS)
+ RELEASE_LOCK(&sched_mutex);
+#endif
+
}
void
{
do {
while (run_queue_hd != END_TSO_QUEUE) {
- waitThread ( run_queue_hd, NULL );
+ waitThread ( run_queue_hd, NULL);
}
while (blocked_queue_hd != END_TSO_QUEUE) {
- waitThread ( blocked_queue_hd, NULL );
+ waitThread ( blocked_queue_hd, NULL);
}
while (sleeping_queue != END_TSO_QUEUE) {
- waitThread ( blocked_queue_hd, NULL );
+ waitThread ( blocked_queue_hd, NULL);
}
} while
(blocked_queue_hd != END_TSO_QUEUE ||
SchedulerStatus
waitThread(StgTSO *tso, /*out*/StgClosure **ret)
+{
+#if defined(THREADED_RTS)
+ return waitThread_(tso,ret, rtsFalse);
+#else
+ return waitThread_(tso,ret);
+#endif
+}
+
+SchedulerStatus
+waitThread_(StgTSO *tso,
+ /*out*/StgClosure **ret
+#if defined(THREADED_RTS)
+ , rtsBool blockWaiting
+#endif
+ )
{
StgMainThread *m;
SchedulerStatus stat;
m->link = main_threads;
main_threads = m;
- IF_DEBUG(scheduler, fprintf(stderr, "== scheduler: new main thread (%d)\n",
- m->tso->id));
+ IF_DEBUG(scheduler, sched_belch("== scheduler: new main thread (%d)\n", m->tso->id));
-#ifdef SMP
- do {
- waitCondition(&m->wakeup, &sched_mutex);
- } while (m->stat == NoStatus);
+#if defined(RTS_SUPPORTS_THREADS)
+
+# if defined(THREADED_RTS)
+ if (!blockWaiting) {
+ /* In the threaded case, the OS thread that called main()
+ * gets to enter the RTS directly without going via another
+ * task/thread.
+ */
+ RELEASE_LOCK(&sched_mutex);
+ schedule();
+ ASSERT(m->stat != NoStatus);
+ } else
+# endif
+ {
+ IF_DEBUG(scheduler, sched_belch("sfoo"));
+ do {
+ waitCondition(&m->wakeup, &sched_mutex);
+ } while (m->stat == NoStatus);
+ }
#elif defined(GRAN)
/* GranSim specific init */
CurrentTSO = m->tso; // the TSO to run
m->tso->id));
free(m);
- RELEASE_LOCK(&sched_mutex);
+#if defined(THREADED_RTS)
+ if (blockWaiting)
+#endif
+ RELEASE_LOCK(&sched_mutex);
return stat;
}
StgAP_UPD * ap;
/* If we find a CATCH_FRAME, and we've got an exception to raise,
- * then build PAP(handler,exception,realworld#), and leave it on
- * top of the stack ready to enter.
+ * then build the THUNK raise(exception), and leave it on
+ * top of the CATCH_FRAME ready to enter.
*/
if (get_itbl(su)->type == CATCH_FRAME && exception != NULL) {
StgCatchFrame *cf = (StgCatchFrame *)su;
+ StgClosure *raise;
+
/* we've got an exception to raise, so let's pass it to the
* handler in this frame.
*/
- ap = (StgAP_UPD *)allocate(sizeofW(StgPAP) + 2);
- TICK_ALLOC_UPD_PAP(3,0);
- SET_HDR(ap,&stg_PAP_info,cf->header.prof.ccs);
-
- ap->n_args = 2;
- ap->fun = cf->handler; /* :: Exception -> IO a */
- ap->payload[0] = exception;
- ap->payload[1] = ARG_TAG(0); /* realworld token */
-
- /* throw away the stack from Sp up to and including the
- * CATCH_FRAME.
- */
- sp = (P_)su + sizeofW(StgCatchFrame) - 1;
- tso->su = cf->link;
-
- /* Restore the blocked/unblocked state for asynchronous exceptions
- * at the CATCH_FRAME.
- *
- * If exceptions were unblocked at the catch, arrange that they
- * are unblocked again after executing the handler by pushing an
- * unblockAsyncExceptions_ret stack frame.
+ raise = (StgClosure *)allocate(sizeofW(StgClosure)+1);
+ TICK_ALLOC_SE_THK(1,0);
+ SET_HDR(raise,&stg_raise_info,cf->header.prof.ccs);
+ raise->payload[0] = exception;
+
+ /* throw away the stack from Sp up to the CATCH_FRAME.
*/
- if (!cf->exceptions_blocked) {
- *(sp--) = (W_)&stg_unblockAsyncExceptionszh_ret_info;
- }
-
- /* Ensure that async exceptions are blocked when running the handler.
+ sp = (P_)su - 1;
+
+ /* Ensure that async excpetions are blocked now, so we don't get
+ * a surprise exception before we get around to executing the
+ * handler.
*/
if (tso->blocked_exceptions == NULL) {
- tso->blocked_exceptions = END_TSO_QUEUE;
+ tso->blocked_exceptions = END_TSO_QUEUE;
}
-
- /* Put the newly-built PAP on top of the stack, ready to execute
+
+ /* Put the newly-built THUNK on top of the stack, ready to execute
* when the thread restarts.
*/
- sp[0] = (W_)ap;
+ sp[0] = (W_)raise;
tso->sp = sp;
+ tso->su = su;
tso->what_next = ThreadEnterGHC;
IF_DEBUG(sanity, checkTSO(tso));
return;
tso->block_info.closure, info_type(tso->block_info.closure));
break;
#endif
+#if defined(RTS_SUPPORTS_THREADS)
+ case BlockedOnCCall:
+ fprintf(stderr,"is blocked on an external call");
+ break;
+#endif
default:
barf("printThreadBlockage: strange tso->why_blocked: %d for TSO %d (%d)",
tso->why_blocked, tso->id, tso);
//@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
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