/* ---------------------------------------------------------------------------
- *
- * (c) The GHC Team, 2002
+ * (c) The GHC Team, 2003
*
* Capabilities
*
* one global capability, namely MainCapability.
*
* --------------------------------------------------------------------------*/
+
#include "PosixSource.h"
#include "Rts.h"
#include "RtsUtils.h"
+#include "RtsFlags.h"
#include "OSThreads.h"
#include "Capability.h"
#include "Schedule.h" /* to get at EMPTY_RUN_QUEUE() */
static rtsBool passingCapability = rtsFalse;
#endif
-/* -----------------------------------------------------------------------------
+#ifdef SMP
+#define UNUSED_IF_NOT_SMP
+#else
+#define UNUSED_IF_NOT_SMP STG_UNUSED
+#endif
+
+/* ----------------------------------------------------------------------------
Initialisation
- -------------------------------------------------------------------------- */
-static
-void
+ ------------------------------------------------------------------------- */
+
+static void
initCapability( Capability *cap )
{
cap->f.stgGCEnter1 = (F_)__stg_gc_enter_1;
static void initCapabilities_(nat n);
#endif
-/*
+/* ---------------------------------------------------------------------------
* Function: initCapabilities()
*
* Purpose: set up the Capability handling. For the SMP build,
* we keep a table of them, the size of which is
* controlled by the user via the RTS flag RtsFlags.ParFlags.nNodes
*
- * Pre-conditions: no locks assumed held.
- */
+ * ------------------------------------------------------------------------- */
void
-initCapabilities()
+initCapabilities( void )
{
#if defined(RTS_SUPPORTS_THREADS)
initCondition(&returning_worker_cond);
/* Capabilities being passed to returning worker threads */
#endif
-/* -----------------------------------------------------------------------------
- Acquiring capabilities
- -------------------------------------------------------------------------- */
+/* ----------------------------------------------------------------------------
+ grabCapability( Capability** )
-/*
- * Function: grabCapability(Capability**)
- *
- * Purpose: the act of grabbing a capability is easy; just
- * 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
- * via the condition variables thread_ready_cond and
- * returning_worker_cond.
- *
- */
-void grabCapability(Capability** cap)
+ (only externally visible when !RTS_SUPPORTS_THREADS. In the
+ threaded RTS, clients must use waitFor*Capability()).
+ ------------------------------------------------------------------------- */
+
+void
+grabCapability( Capability** cap )
{
#if !defined(SMP)
ASSERT(rts_n_free_capabilities == 1);
IF_DEBUG(scheduler, sched_belch("worker: got capability"));
}
-/*
+/* ----------------------------------------------------------------------------
* Function: releaseCapability(Capability*)
*
* Purpose: Letting go of a capability. Causes a
* 'returning worker' thread or a 'waiting worker'
* to wake up, in that order.
- *
- */
-void releaseCapability(Capability* cap
-#if !defined(SMP)
- STG_UNUSED
-#endif
-)
-{ // Precondition: sched_mutex must be held
+ * ------------------------------------------------------------------------- */
+
+void
+releaseCapability( Capability* cap UNUSED_IF_NOT_SMP )
+{
+ // Precondition: sched_mutex is held.
#if defined(RTS_SUPPORTS_THREADS)
#ifndef SMP
- ASSERT(rts_n_free_capabilities == 0);
+ ASSERT(rts_n_free_capabilities == 0);
#endif
- /* Check to see whether a worker thread can be given
- the go-ahead to return the result of an external call..*/
- if (rts_n_waiting_workers > 0) {
- /* Decrement the counter here to avoid livelock where the
- * thread that is yielding its capability will repeatedly
- * signal returning_worker_cond.
- */
+ // Check to see whether a worker thread can be given
+ // the go-ahead to return the result of an external call..
+ if (rts_n_waiting_workers > 0) {
+ // Decrement the counter here to avoid livelock where the
+ // thread that is yielding its capability will repeatedly
+ // signal returning_worker_cond.
+
#if defined(SMP)
// SMP variant untested
- cap->link = returning_capabilities;
- returning_capabilities = cap;
-#else
+ cap->link = returning_capabilities;
+ returning_capabilities = cap;
#endif
- rts_n_waiting_workers--;
- signalCondition(&returning_worker_cond);
- IF_DEBUG(scheduler, sched_belch("worker: released capability to returning worker"));
- } else /*if ( !EMPTY_RUN_QUEUE() )*/ {
+
+ rts_n_waiting_workers--;
+ signalCondition(&returning_worker_cond);
+ IF_DEBUG(scheduler, sched_belch("worker: released capability to returning worker"));
+ } else if (passingCapability) {
+ if (passTarget == NULL) {
+ signalCondition(&thread_ready_cond);
+ startSchedulerTaskIfNecessary();
+ } else {
+ signalCondition(passTarget);
+ }
+ rts_n_free_capabilities = 1;
+ IF_DEBUG(scheduler, sched_belch("worker: released capability, passing it"));
+
+ } else {
#if defined(SMP)
- cap->link = free_capabilities;
- free_capabilities = cap;
- rts_n_free_capabilities++;
+ cap->link = free_capabilities;
+ free_capabilities = cap;
+ rts_n_free_capabilities++;
#else
- rts_n_free_capabilities = 1;
+ rts_n_free_capabilities = 1;
#endif
- /* Signal that a capability is available */
- signalCondition(&thread_ready_cond);
- startSchedulerTaskIfNecessary(); // if there is more work to be done,
- // we'll need a new thread
- IF_DEBUG(scheduler, sched_belch("worker: released capability"));
- }
+ // Signal that a capability is available
+ signalCondition(&thread_ready_cond);
+ startSchedulerTaskIfNecessary();
+ IF_DEBUG(scheduler, sched_belch("worker: released capability"));
+ }
#endif
- return;
+ return;
}
#if defined(RTS_SUPPORTS_THREADS)
* call, it needs to communicate the result back. This is done
* as follows:
*
- * - in resumeThread(), the thread calls grabReturnCapability().
- * - If no capabilities are readily available, grabReturnCapability()
+ * - in resumeThread(), the thread calls waitForReturnCapability().
+ * - If no capabilities are readily available, waitForReturnCapability()
* increments a counter rts_n_waiting_workers, and blocks
* waiting for the condition returning_worker_cond to become
* signalled.
* to re-grab a capability and re-enter the Scheduler.
*/
-/*
- * Function: grabReturnCapability(Capability**)
+/* ----------------------------------------------------------------------------
+ * waitForReturnCapability( Mutext *pMutex, Capability** )
*
* Purpose: when an OS thread returns from an external call,
* it calls grabReturnCapability() (via Schedule.resumeThread())
* result of the external call back to the Haskell thread that
* made it.
*
- * Pre-condition: pMutex is held.
- * Post-condition: pMutex is still held and a capability has
- * been assigned to the worker thread.
- */
+ * ------------------------------------------------------------------------- */
+
void
-grabReturnCapability(Mutex* pMutex, Capability** pCap)
+waitForReturnCapability( Mutex* pMutex, Capability** pCap )
{
- IF_DEBUG(scheduler,
- sched_belch("worker: returning; workers waiting: %d",
- rts_n_waiting_workers));
- if ( noCapabilities() || passingCapability ) {
- rts_n_waiting_workers++;
- wakeBlockedWorkerThread();
- context_switch = 1; // make sure it's our turn soon
- waitCondition(&returning_worker_cond, pMutex);
+ // Pre-condition: pMutex is held.
+
+ IF_DEBUG(scheduler,
+ sched_belch("worker: returning; workers waiting: %d",
+ rts_n_waiting_workers));
+
+ if ( noCapabilities() || passingCapability ) {
+ rts_n_waiting_workers++;
+ wakeBlockedWorkerThread();
+ context_switch = 1; // make sure it's our turn soon
+ waitCondition(&returning_worker_cond, pMutex);
#if defined(SMP)
- *pCap = returning_capabilities;
- returning_capabilities = (*pCap)->link;
+ *pCap = returning_capabilities;
+ returning_capabilities = (*pCap)->link;
#else
- *pCap = &MainCapability;
- ASSERT(rts_n_free_capabilities == 0);
- handleSignalsInThisThread();
+ *pCap = &MainCapability;
+ ASSERT(rts_n_free_capabilities == 0);
+ handleSignalsInThisThread();
#endif
- } else {
- grabCapability(pCap);
- }
- return;
+ } else {
+ grabCapability(pCap);
+ }
+
+ // Post-condition: pMutex is held, pCap points to a capability
+ // which is now held by the current thread.
+ return;
}
-/* -----------------------------------------------------------------------------
- Yielding/waiting for capabilities
- -------------------------------------------------------------------------- */
+/* ----------------------------------------------------------------------------
+ * yieldCapability( Mutex* pMutex, Capability** pCap )
+ * ------------------------------------------------------------------------- */
-/*
- * Function: yieldToReturningWorker(Mutex*,Capability*,Condition*)
- *
- * 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.
- * Immediately afterwards, it tries to reaquire the Capabilty
- * using waitForWorkCapability.
- *
- *
- * Pre-condition: pMutex is assumed held and the thread possesses
- * a Capability.
- * Post-condition: pMutex is held and the thread possesses
- * a Capability.
- */
void
-yieldToReturningWorker(Mutex* pMutex, Capability** pCap, Condition* pThreadCond)
+yieldCapability( Capability** pCap )
{
- if ( rts_n_waiting_workers > 0 ) {
- IF_DEBUG(scheduler, sched_belch("worker: giving up capability"));
- releaseCapability(*pCap);
- /* And wait for work */
- waitForWorkCapability(pMutex, pCap, pThreadCond);
- IF_DEBUG(scheduler,
- sched_belch("worker: got back capability (after yieldToReturningWorker)"));
- }
- return;
+ // Pre-condition: pMutex is assumed held, the current thread
+ // holds the capability pointed to by pCap.
+
+ if ( rts_n_waiting_workers > 0 || passingCapability ) {
+ IF_DEBUG(scheduler, sched_belch("worker: giving up capability"));
+ releaseCapability(*pCap);
+ *pCap = NULL;
+ }
+
+ // Post-condition: pMutex is assumed held, and either:
+ //
+ // 1. *pCap is NULL, in which case the current thread does not
+ // hold a capability now, or
+ // 2. *pCap is not NULL, in which case the current thread still
+ // holds the capability.
+ //
+ return;
}
-/*
- * Function: waitForWorkCapability(Mutex*, Capability**, Condition*)
+/* ----------------------------------------------------------------------------
+ * waitForCapability( Mutex*, Capability**, Condition* )
*
* Purpose: wait for a Capability to become available. In
* the process of doing so, updates the number
* call is made.
* If pThreadCond is not NULL, a capability can be specifically
* passed to this thread using passCapability.
- *
- * Pre-condition: pMutex is held.
- * Post-condition: pMutex is held and *pCap is held by the current thread
- */
+ * ------------------------------------------------------------------------- */
void
-waitForWorkCapability(Mutex* pMutex, Capability** pCap, Condition* pThreadCond)
+waitForCapability( Mutex* pMutex, Capability** pCap, Condition* pThreadCond )
{
-#ifdef SMP
- #error SMP version not implemented
-#endif
- while ( noCapabilities() || (passingCapability && passTarget != pThreadCond)) {
- IF_DEBUG(scheduler,
- sched_belch("worker: wait for capability (cond: %p)",
- pThreadCond));
- if(pThreadCond)
- {
- waitCondition(pThreadCond, pMutex);
- IF_DEBUG(scheduler, sched_belch("worker: get passed capability"));
- }
- else
- {
- rts_n_waiting_tasks++;
- waitCondition(&thread_ready_cond, pMutex);
- rts_n_waiting_tasks--;
- IF_DEBUG(scheduler, sched_belch("worker: get normal capability"));
+ // Pre-condition: pMutex is held.
+
+ while ( noCapabilities() ||
+ (passingCapability && passTarget != pThreadCond)) {
+ IF_DEBUG(scheduler,
+ sched_belch("worker: wait for capability (cond: %p)",
+ pThreadCond));
+
+ if (pThreadCond != NULL) {
+ waitCondition(pThreadCond, pMutex);
+ IF_DEBUG(scheduler, sched_belch("worker: get passed capability"));
+ } else {
+ rts_n_waiting_tasks++;
+ waitCondition(&thread_ready_cond, pMutex);
+ rts_n_waiting_tasks--;
+ IF_DEBUG(scheduler, sched_belch("worker: get normal capability"));
+ }
}
- }
- passingCapability = rtsFalse;
- grabCapability(pCap);
- return;
+ passingCapability = rtsFalse;
+ grabCapability(pCap);
+
+ // Post-condition: pMutex is held and *pCap is held by the current thread
+ return;
}
-/*
- * Function: passCapability(Mutex*, Capability*, Condition*)
- *
- * Purpose: Let go of the capability and make sure the thread associated
- * with the Condition pTargetThreadCond gets it next.
- *
- * Pre-condition: pMutex is held and cap is held by the current thread
- * Post-condition: pMutex is held; cap will be grabbed by the "target"
- * thread when pMutex is released.
- */
+/* ----------------------------------------------------------------------------
+ passCapability, passCapabilityToWorker
+ ------------------------------------------------------------------------- */
void
-passCapability(Mutex* pMutex, Capability* cap, Condition *pTargetThreadCond)
+passCapability( Condition *pTargetThreadCond )
{
-#ifdef SMP
- #error SMP version not implemented
-#endif
- ASSERT(rts_n_free_capabilities == 0);
- rts_n_free_capabilities = 1;
- signalCondition(pTargetThreadCond);
+ // Pre-condition: pMutex is held and cap is held by the current thread
+
passTarget = pTargetThreadCond;
passingCapability = rtsTrue;
IF_DEBUG(scheduler, sched_belch("worker: passCapability"));
-}
-/*
- * Function: passCapabilityToWorker(Mutex*, Capability*)
- *
- * Purpose: Let go of the capability and make sure that a
- * "plain" worker thread (not a bound thread) gets it next.
- *
- * Pre-condition: pMutex is held and cap is held by the current thread
- * Post-condition: pMutex is held; cap will be grabbed by the "target"
- * thread when pMutex is released.
- */
+ // Post-condition: pMutex is held; cap is still held, but will be
+ // passed to the target thread when next released.
+}
void
-passCapabilityToWorker(Mutex* pMutex, Capability* cap)
+passCapabilityToWorker( void )
{
-#ifdef SMP
- #error SMP version not implemented
-#endif
- rts_n_free_capabilities = 1;
- signalCondition(&thread_ready_cond);
- startSchedulerTaskIfNecessary();
+ // Pre-condition: pMutex is held and cap is held by the current thread
+
passTarget = NULL;
passingCapability = rtsTrue;
IF_DEBUG(scheduler, sched_belch("worker: passCapabilityToWorker"));
-}
-
+ // Post-condition: pMutex is held; cap is still held, but will be
+ // passed to a worker thread when next released.
+}
#endif /* RTS_SUPPORTS_THREADS */
+/* ------------------------------------------------------------------------- */
+
#if defined(SMP)
/*
* Function: initCapabilities_(nat)
/* ---------------------------------------------------------------------------
- * $Id: Schedule.c,v 1.182 2003/12/12 16:35:20 simonmar Exp $
+ * $Id: Schedule.c,v 1.183 2003/12/16 13:27:32 simonmar Exp $
*
- * (c) The GHC Team, 1998-2000
+ * (c) The GHC Team, 1998-2003
*
* Scheduler
*
*
* WAY Name CPP flag What's it for
* --------------------------------------
- * mp GUM PAR Parallel execution on a distributed memory machine
+ * mp GUM PAR Parallel execution on a distrib. memory machine
* s SMP SMP Parallel execution on a shared memory machine
* mg GranSim GRAN Simulation of parallel execution
* md GUM/GdH DIST Distributed execution (based on GUM)
*
* --------------------------------------------------------------------------*/
-//@node Main scheduling code, , ,
-//@section Main scheduling code
-
/*
- * Version with scheduler monitor support for SMPs (WAY=s):
-
- This design provides a high-level API to create and schedule threads etc.
- as documented in the SMP design document.
-
- It uses a monitor design controlled by a single mutex to exercise control
- over accesses to shared data structures, and builds on the Posix threads
- library.
-
- The majority of state is shared. In order to keep essential per-task state,
- there is a Capability structure, which contains all the information
- needed to run a thread: its STG registers, a pointer to its TSO, a
- nursery etc. During STG execution, a pointer to the capability is
- kept in a register (BaseReg).
-
- In a non-SMP build, there is one global capability, namely MainRegTable.
-
- SDM & KH, 10/99
-
* Version with support for distributed memory parallelism aka GUM (WAY=mp):
The main scheduling loop in GUM iterates until a finish message is received.
over the events in the global event queue. -- HWL
*/
-//@menu
-//* Includes::
-//* Variables and Data structures::
-//* Main scheduling loop::
-//* Suspend and Resume::
-//* Run queue code::
-//* Garbage Collextion Routines::
-//* Blocking Queue Routines::
-//* Exception Handling Routines::
-//* Debugging Routines::
-//* Index::
-//@end menu
-
-//@node Includes, Variables and Data structures, Main scheduling code, Main scheduling code
-//@subsection Includes
-
#include "PosixSource.h"
#include "Rts.h"
#include "SchedAPI.h"
#define USED_WHEN_RTS_SUPPORTS_THREADS STG_UNUSED
#endif
-//@node Variables and Data structures, Prototypes, Includes, Main scheduling code
-//@subsection Variables and Data structures
-
/* Main thread queue.
* Locks required: sched_mutex.
*/
*/
/* flag set by signal handler to precipitate a context switch */
-//@cindex context_switch
nat context_switch = 0;
/* if this flag is set as well, give up execution */
-//@cindex interrupted
rtsBool interrupted = rtsFalse;
/* Next thread ID to allocate.
* Locks required: thread_id_mutex
*/
-//@cindex next_thread_id
static StgThreadID next_thread_id = 1;
/*
*/
Mutex thread_id_mutex = INIT_MUTEX_VAR;
-
-# if defined(SMP)
-static Condition gc_pending_cond = INIT_COND_VAR;
-nat await_death;
-# endif
-
#endif /* RTS_SUPPORTS_THREADS */
#if defined(PAR)
StgTSO * activateSpark (rtsSpark spark);
#endif
-/*
- * The thread state for the main thread.
-// ToDo: check whether not needed any more
-StgTSO *MainTSO;
- */
+/* ----------------------------------------------------------------------------
+ * Starting Tasks
+ * ------------------------------------------------------------------------- */
#if defined(RTS_SUPPORTS_THREADS)
static rtsBool startingWorkerThread = rtsFalse;
static void
taskStart(void)
{
- Capability *cap;
-
ACQUIRE_LOCK(&sched_mutex);
- startingWorkerThread = rtsFalse;
- waitForWorkCapability(&sched_mutex, &cap, NULL);
+ schedule(NULL,NULL);
RELEASE_LOCK(&sched_mutex);
-
- schedule(NULL,cap);
}
void
}
#endif
-//@node Main scheduling loop, Suspend and Resume, Prototypes, Main scheduling code
-//@subsection Main scheduling loop
-
/* ---------------------------------------------------------------------------
Main scheduling loop.
This is not the ugliest code you could imagine, but it's bloody close.
------------------------------------------------------------------------ */
-//@cindex schedule
static void
schedule( StgMainThread *mainThread USED_WHEN_RTS_SUPPORTS_THREADS,
Capability *initialCapability )
rtsBool was_interrupted = rtsFalse;
StgTSOWhatNext prev_what_next;
- ACQUIRE_LOCK(&sched_mutex);
+ // Pre-condition: sched_mutex is held.
#if defined(RTS_SUPPORTS_THREADS)
//
mainThread, initialCapability);
);
#else
- /* simply initialise it in the non-threaded case */
+ // simply initialise it in the non-threaded case
grabCapability(&cap);
#endif
IF_DEBUG(scheduler, printAllThreads());
#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... if we have a capability, that is.
- //
- if (cap != NULL) {
- yieldToReturningWorker(&sched_mutex, &cap,
- mainThread ? &mainThread->bound_thread_cond
- : NULL);
- }
+ // Yield the capability to higher-priority tasks if necessary.
+ //
+ if (cap != NULL) {
+ yieldCapability(&cap);
+ }
- // If we do not currently hold a capability, we wait for one
- if (cap == NULL) {
- waitForWorkCapability(&sched_mutex, &cap,
- mainThread ? &mainThread->bound_thread_cond
- : NULL);
- }
+ // If we do not currently hold a capability, we wait for one
+ //
+ if (cap == NULL) {
+ waitForCapability(&sched_mutex, &cap,
+ mainThread ? &mainThread->bound_thread_cond : NULL);
+ }
+
+ // We now have a capability...
#endif
//
removeThreadLabel((StgWord)m->tso->id);
#endif
releaseCapability(cap);
- RELEASE_LOCK(&sched_mutex);
return;
}
else
// the scheduler loop in it's bound OS thread has to
// return, so let's pass our capability directly to
// that thread.
- passCapability(&sched_mutex, cap, &m->bound_thread_cond);
- cap = NULL;
+ passCapability(&m->bound_thread_cond);
}
}
}
}
- // If we gave our capability away, go to the top to get it back
- if (cap == NULL) {
- continue;
- }
-
#else /* not threaded */
# if defined(PAR)
#endif
-#if 0 /* defined(SMP) */
- /* Top up the run queue from our spark pool. We try to make the
- * number of threads in the run queue equal to the number of
- * free capabilities.
- *
- * Disable spark support in SMP for now, non-essential & requires
- * a little bit of work to make it compile cleanly. -- sof 1/02.
- */
- {
- nat n = getFreeCapabilities();
- StgTSO *tso = run_queue_hd;
-
- /* Count the run queue */
- while (n > 0 && tso != END_TSO_QUEUE) {
- tso = tso->link;
- n--;
- }
-
- for (; n > 0; n--) {
- StgClosure *spark;
- spark = findSpark(rtsFalse);
- if (spark == NULL) {
- break; /* no more sparks in the pool */
- } else {
- /* I'd prefer this to be done in activateSpark -- HWL */
- /* tricky - it needs to hold the scheduler lock and
- * not try to re-acquire it -- SDM */
- createSparkThread(spark);
- IF_DEBUG(scheduler,
- sched_belch("==^^ turning spark of closure %p into a thread",
- (StgClosure *)spark));
- }
- }
- /* We need to wake up the other tasks if we just created some
- * work for them.
- */
- if (getFreeCapabilities() - n > 1) {
- signalCondition( &thread_ready_cond );
- }
- }
-#endif // SMP
-
#if defined(RTS_USER_SIGNALS)
// check for signals each time around the scheduler
if (signals_pending()) {
* can wait indefinitely for something to happen.
*/
if ( !EMPTY_QUEUE(blocked_queue_hd) || !EMPTY_QUEUE(sleeping_queue)
-#if defined(RTS_SUPPORTS_THREADS) && !defined(SMP)
+#if defined(RTS_SUPPORTS_THREADS)
|| EMPTY_RUN_QUEUE()
#endif
)
{
- awaitEvent( EMPTY_RUN_QUEUE()
-#if defined(SMP)
- && allFreeCapabilities()
-#endif
- );
+ awaitEvent( EMPTY_RUN_QUEUE() );
}
/* we can be interrupted while waiting for I/O... */
if (interrupted) continue;
* inform all the main threads.
*/
#if !defined(PAR) && !defined(RTS_SUPPORTS_THREADS)
- if ( EMPTY_THREAD_QUEUES()
-#if defined(RTS_SUPPORTS_THREADS)
- && EMPTY_QUEUE(suspended_ccalling_threads)
-#endif
-#ifdef SMP
- && allFreeCapabilities()
-#endif
- )
+ if ( EMPTY_THREAD_QUEUES() )
{
IF_DEBUG(scheduler, sched_belch("deadlocked, forcing major GC..."));
-#if defined(THREADED_RTS)
- /* and SMP mode ..? */
- releaseCapability(cap);
-#endif
// Garbage collection can release some new threads due to
// either (a) finalizers or (b) threads resurrected because
// they are about to be send BlockedOnDeadMVar. Any threads
* for signals to arrive rather then bombing out with a
* deadlock.
*/
-#if defined(RTS_SUPPORTS_THREADS)
- if ( 0 ) { /* hmm..what to do? Simply stop waiting for
- a signal with no runnable threads (or I/O
- suspended ones) leads nowhere quick.
- For now, simply shut down when we reach this
- condition.
-
- ToDo: define precisely under what conditions
- the Scheduler should shut down in an MT setting.
- */
-#else
if ( anyUserHandlers() ) {
-#endif
IF_DEBUG(scheduler,
sched_belch("still deadlocked, waiting for signals..."));
*/
{
StgMainThread *m;
-#if defined(RTS_SUPPORTS_THREADS)
- for (m = main_threads; m != NULL; m = m->link) {
- switch (m->tso->why_blocked) {
- case BlockedOnBlackHole:
- raiseAsync(m->tso, (StgClosure *)NonTermination_closure);
- break;
- case BlockedOnException:
- case BlockedOnMVar:
- raiseAsync(m->tso, (StgClosure *)Deadlock_closure);
- break;
- default:
- barf("deadlock: main thread blocked in a strange way");
- }
- }
-#else
m = main_threads;
switch (m->tso->why_blocked) {
case BlockedOnBlackHole:
default:
barf("deadlock: main thread blocked in a strange way");
}
-#endif
}
-
-#if defined(RTS_SUPPORTS_THREADS)
- /* ToDo: revisit conditions (and mechanism) for shutting
- down a multi-threaded world */
- IF_DEBUG(scheduler, sched_belch("all done, i think...shutting down."));
- RELEASE_LOCK(&sched_mutex);
- shutdownHaskell();
- return;
-#endif
}
not_deadlocked:
#elif defined(RTS_SUPPORTS_THREADS)
- /* ToDo: add deadlock detection in threaded RTS */
+ // ToDo: add deadlock detection in threaded RTS
#elif defined(PAR)
- /* ToDo: add deadlock detection in GUM (similar to SMP) -- HWL */
+ // ToDo: add deadlock detection in GUM (similar to SMP) -- HWL
#endif
-#if defined(SMP)
- /* If there's a GC pending, don't do anything until it has
- * completed.
- */
- if (ready_to_gc) {
- IF_DEBUG(scheduler,sched_belch("waiting for GC"));
- waitCondition( &gc_pending_cond, &sched_mutex );
- }
-#endif
-
#if defined(RTS_SUPPORTS_THREADS)
-#if defined(SMP)
- /* block until we've got a thread on the run queue and a free
- * capability.
- *
- */
- if ( EMPTY_RUN_QUEUE() ) {
- /* Give up our capability */
- releaseCapability(cap);
-
- /* If we're in the process of shutting down (& running the
- * a batch of finalisers), don't wait around.
- */
- if ( shutting_down_scheduler ) {
- RELEASE_LOCK(&sched_mutex);
- return;
- }
- IF_DEBUG(scheduler, sched_belch("waiting for work"));
- waitForWorkCapability(&sched_mutex, &cap, rtsTrue);
- IF_DEBUG(scheduler, sched_belch("work now available"));
- }
-#else
if ( EMPTY_RUN_QUEUE() ) {
continue; // nothing to do
}
#endif
-#endif
#if defined(GRAN)
if (RtsFlags.GranFlags.Light)
sched_belch("### thread %d bound to another OS thread", t->id));
// no, bound to a different Haskell thread: pass to that thread
PUSH_ON_RUN_QUEUE(t);
- passCapability(&sched_mutex,cap,&m->bound_thread_cond);
- cap = NULL;
+ passCapability(&m->bound_thread_cond);
continue;
}
}
// no, the current native thread is bound to a different
// Haskell thread, so pass it to any worker thread
PUSH_ON_RUN_QUEUE(t);
- passCapabilityToWorker(&sched_mutex, cap);
- cap = NULL;
+ passCapabilityToWorker();
continue;
}
}
}
#endif
- if (ready_to_gc
-#ifdef SMP
- && allFreeCapabilities()
-#endif
- ) {
+ if (ready_to_gc) {
/* 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
#endif
GarbageCollect(GetRoots,rtsFalse);
ready_to_gc = rtsFalse;
-#ifdef SMP
- broadcastCondition(&gc_pending_cond);
-#endif
#if defined(GRAN)
/* add a ContinueThread event to continue execution of current thread */
new_event(CurrentProc, CurrentProc, CurrentTime[CurrentProc],
/* startThread and insertThread are now in GranSim.c -- HWL */
-//@node Suspend and Resume, Run queue code, Main scheduling loop, Main scheduling code
-//@subsection Suspend and Resume
-
/* ---------------------------------------------------------------------------
* Suspending & resuming Haskell threads.
*
StgInt
suspendThread( StgRegTable *reg,
rtsBool concCall
-#if !defined(RTS_SUPPORTS_THREADS) && !defined(DEBUG)
+#if !defined(DEBUG)
STG_UNUSED
#endif
)
#if defined(RTS_SUPPORTS_THREADS)
/* Wait for permission to re-enter the RTS with the result. */
ACQUIRE_LOCK(&sched_mutex);
- grabReturnCapability(&sched_mutex, &cap);
+ waitForReturnCapability(&sched_mutex, &cap);
IF_DEBUG(scheduler, sched_belch("worker (token %d): re-entering RTS", tok));
#else
tso->why_blocked = NotBlocked;
cap->r.rCurrentTSO = tso;
-#if defined(RTS_SUPPORTS_THREADS)
RELEASE_LOCK(&sched_mutex);
-#endif
errno = saved_errno;
return &cap->r;
}
currently pri (priority) is only used in a GRAN setup -- HWL
------------------------------------------------------------------------ */
-//@cindex createThread
#if defined(GRAN)
/* currently pri (priority) is only used in a GRAN setup -- HWL */
StgTSO *
ToDo: fix for SMP (needs to acquire SCHED_MUTEX!)
*/
#if defined(PAR)
-//@cindex activateSpark
StgTSO *
activateSpark (rtsSpark spark)
{
}
SchedulerStatus
-scheduleWaitThread(StgTSO* tso, /*[out]*/HaskellObj* ret, Capability *initialCapability)
-{ // Precondition: sched_mutex must be held
- StgMainThread *m;
+scheduleWaitThread(StgTSO* tso, /*[out]*/HaskellObj* ret,
+ Capability *initialCapability)
+{
+ // Precondition: sched_mutex must be held
+ StgMainThread *m;
- m = stgMallocBytes(sizeof(StgMainThread), "waitThread");
- m->tso = tso;
- m->ret = ret;
- m->stat = NoStatus;
+ m = stgMallocBytes(sizeof(StgMainThread), "waitThread");
+ m->tso = tso;
+ m->ret = ret;
+ m->stat = NoStatus;
#if defined(RTS_SUPPORTS_THREADS)
-#if defined(THREADED_RTS)
- initCondition(&m->bound_thread_cond);
-#else
- initCondition(&m->wakeup);
-#endif
+ initCondition(&m->bound_thread_cond);
#endif
- /* Put the thread on the main-threads list prior to scheduling the TSO.
- Failure to do so introduces a race condition in the MT case (as
- identified by Wolfgang Thaller), whereby the new task/OS thread
- created by scheduleThread_() would complete prior to the thread
- that spawned it managed to put 'itself' on the main-threads list.
- The upshot of it all being that the worker thread wouldn't get to
- signal the completion of the its work item for the main thread to
- see (==> it got stuck waiting.) -- sof 6/02.
- */
- IF_DEBUG(scheduler, sched_belch("waiting for thread (%d)", tso->id));
-
- m->link = main_threads;
- main_threads = m;
-
- scheduleThread_(tso);
+ /* Put the thread on the main-threads list prior to scheduling the TSO.
+ Failure to do so introduces a race condition in the MT case (as
+ identified by Wolfgang Thaller), whereby the new task/OS thread
+ created by scheduleThread_() would complete prior to the thread
+ that spawned it managed to put 'itself' on the main-threads list.
+ The upshot of it all being that the worker thread wouldn't get to
+ signal the completion of the its work item for the main thread to
+ see (==> it got stuck waiting.) -- sof 6/02.
+ */
+ IF_DEBUG(scheduler, sched_belch("waiting for thread (%d)", tso->id));
+
+ m->link = main_threads;
+ main_threads = m;
+
+ scheduleThread_(tso);
- return waitThread_(m, initialCapability);
+ return waitThread_(m, initialCapability);
}
/* ---------------------------------------------------------------------------
*
* ------------------------------------------------------------------------ */
-#ifdef SMP
-static void
-term_handler(int sig STG_UNUSED)
-{
- stat_workerStop();
- ACQUIRE_LOCK(&term_mutex);
- await_death--;
- RELEASE_LOCK(&term_mutex);
- shutdownThread();
-}
-#endif
-
void
initScheduler(void)
{
initCondition(&thread_ready_cond);
#endif
-#if defined(SMP)
- initCondition(&gc_pending_cond);
-#endif
-
#if defined(RTS_SUPPORTS_THREADS)
ACQUIRE_LOCK(&sched_mutex);
#endif
- /* Install the SIGHUP handler */
-#if defined(SMP)
- {
- struct sigaction action,oact;
-
- action.sa_handler = term_handler;
- sigemptyset(&action.sa_mask);
- action.sa_flags = 0;
- if (sigaction(SIGTERM, &action, &oact) != 0) {
- barf("can't install TERM handler");
- }
- }
-#endif
-
/* A capability holds the state a native thread needs in
* order to execute STG code. At least one capability is
* floating around (only SMP builds have more than one).
#if defined(RTS_SUPPORTS_THREADS)
/* start our haskell execution tasks */
-# if defined(SMP)
- startTaskManager(RtsFlags.ParFlags.nNodes, taskStart);
-# else
startTaskManager(0,taskStart);
-# endif
#endif
#if /* defined(SMP) ||*/ defined(PAR)
initSparkPools();
#endif
-#if defined(RTS_SUPPORTS_THREADS)
RELEASE_LOCK(&sched_mutex);
-#endif
}
shutting_down_scheduler = rtsTrue;
}
-/* -----------------------------------------------------------------------------
+/* ----------------------------------------------------------------------------
Managing the per-task allocation areas.
Each capability comes with an allocation area. These are
fixed-length block lists into which allocation can be done.
ToDo: no support for two-space collection at the moment???
- -------------------------------------------------------------------------- */
-
-/* -----------------------------------------------------------------------------
- * waitThread is the external interface for running a new computation
- * and waiting for the result.
- *
- * In the non-SMP case, we create a new main thread, push it on the
- * main-thread stack, and invoke the scheduler to run it. The
- * scheduler will return when the top main thread on the stack has
- * completed or died, and fill in the necessary fields of the
- * main_thread structure.
- *
- * In the SMP case, we create a main thread as before, but we then
- * create a new condition variable and sleep on it. When our new
- * main thread has completed, we'll be woken up and the status/result
- * will be in the main_thread struct.
- * -------------------------------------------------------------------------- */
-
-int
-howManyThreadsAvail ( void )
-{
- int i = 0;
- StgTSO* q;
- for (q = run_queue_hd; q != END_TSO_QUEUE; q = q->link)
- i++;
- for (q = blocked_queue_hd; q != END_TSO_QUEUE; q = q->link)
- i++;
- for (q = sleeping_queue; q != END_TSO_QUEUE; q = q->link)
- i++;
- return i;
-}
-
-void
-finishAllThreads ( void )
-{
- do {
- while (run_queue_hd != END_TSO_QUEUE) {
- waitThread ( run_queue_hd, NULL, NULL );
- }
- while (blocked_queue_hd != END_TSO_QUEUE) {
- waitThread ( blocked_queue_hd, NULL, NULL );
- }
- while (sleeping_queue != END_TSO_QUEUE) {
- waitThread ( blocked_queue_hd, NULL, NULL );
- }
- } while
- (blocked_queue_hd != END_TSO_QUEUE ||
- run_queue_hd != END_TSO_QUEUE ||
- sleeping_queue != END_TSO_QUEUE);
-}
-
-SchedulerStatus
-waitThread(StgTSO *tso, /*out*/StgClosure **ret, Capability *initialCapability)
-{
- StgMainThread *m;
- SchedulerStatus stat;
-
- m = stgMallocBytes(sizeof(StgMainThread), "waitThread");
- m->tso = tso;
- m->ret = ret;
- m->stat = NoStatus;
-#if defined(RTS_SUPPORTS_THREADS)
-#if defined(THREADED_RTS)
- initCondition(&m->bound_thread_cond);
-#else
- initCondition(&m->wakeup);
-#endif
-#endif
-
- /* see scheduleWaitThread() comment */
- ACQUIRE_LOCK(&sched_mutex);
- m->link = main_threads;
- main_threads = m;
-
- IF_DEBUG(scheduler, sched_belch("waiting for thread %d", tso->id));
-
- stat = waitThread_(m,initialCapability);
-
- RELEASE_LOCK(&sched_mutex);
- return stat;
-}
+ ------------------------------------------------------------------------- */
static
SchedulerStatus
// Precondition: sched_mutex must be held.
IF_DEBUG(scheduler, sched_belch("new main thread (%d)", m->tso->id));
-#if defined(RTS_SUPPORTS_THREADS) && !defined(THREADED_RTS)
- { // FIXME: does this still make sense?
- // It's not for the threaded rts => SMP only
- do {
- waitCondition(&m->wakeup, &sched_mutex);
- } while (m->stat == NoStatus);
- }
-#elif defined(GRAN)
+#if defined(GRAN)
/* GranSim specific init */
CurrentTSO = m->tso; // the TSO to run
procStatus[MainProc] = Busy; // status of main PE
CurrentProc = MainProc; // PE to run it on
-
- RELEASE_LOCK(&sched_mutex);
schedule(m,initialCapability);
#else
- RELEASE_LOCK(&sched_mutex);
schedule(m,initialCapability);
- ACQUIRE_LOCK(&sched_mutex);
ASSERT(m->stat != NoStatus);
#endif
stat = m->stat;
#if defined(RTS_SUPPORTS_THREADS)
-#if defined(THREADED_RTS)
closeCondition(&m->bound_thread_cond);
-#else
- closeCondition(&m->wakeup);
-#endif
#endif
- IF_DEBUG(scheduler, fprintf(stderr, "== sched: main thread (%d) finished\n",
- m->tso->id));
+ IF_DEBUG(scheduler, sched_belch("main thread (%d) finished", m->tso->id));
stgFree(m);
// Postcondition: sched_mutex still held
return stat;
}
-//@node Run queue code, Garbage Collextion Routines, Suspend and Resume, Main scheduling code
-//@subsection Run queue code
-
-#if 0
-/*
- NB: In GranSim we have many run queues; run_queue_hd is actually a macro
- unfolding to run_queue_hds[CurrentProc], thus CurrentProc is an
- implicit global variable that has to be correct when calling these
- fcts -- HWL
-*/
-
-/* Put the new thread on the head of the runnable queue.
- * The caller of createThread better push an appropriate closure
- * on this thread's stack before the scheduler is invoked.
- */
-static /* inline */ void
-add_to_run_queue(tso)
-StgTSO* tso;
-{
- ASSERT(tso!=run_queue_hd && tso!=run_queue_tl);
- tso->link = run_queue_hd;
- run_queue_hd = tso;
- if (run_queue_tl == END_TSO_QUEUE) {
- run_queue_tl = tso;
- }
-}
-
-/* Put the new thread at the end of the runnable queue. */
-static /* inline */ void
-push_on_run_queue(tso)
-StgTSO* tso;
-{
- ASSERT(get_itbl((StgClosure *)tso)->type == TSO);
- ASSERT(run_queue_hd!=NULL && run_queue_tl!=NULL);
- ASSERT(tso!=run_queue_hd && tso!=run_queue_tl);
- if (run_queue_hd == END_TSO_QUEUE) {
- run_queue_hd = tso;
- } else {
- run_queue_tl->link = tso;
- }
- run_queue_tl = tso;
-}
-
-/*
- Should be inlined because it's used very often in schedule. The tso
- argument is actually only needed in GranSim, where we want to have the
- possibility to schedule *any* TSO on the run queue, irrespective of the
- actual ordering. Therefore, if tso is not the nil TSO then we traverse
- the run queue and dequeue the tso, adjusting the links in the queue.
-*/
-//@cindex take_off_run_queue
-static /* inline */ StgTSO*
-take_off_run_queue(StgTSO *tso) {
- StgTSO *t, *prev;
-
- /*
- qetlaHbogh Qu' ngaSbogh ghomDaQ {tso} yIteq!
-
- if tso is specified, unlink that tso from the run_queue (doesn't have
- to be at the beginning of the queue); GranSim only
- */
- if (tso!=END_TSO_QUEUE) {
- /* find tso in queue */
- for (t=run_queue_hd, prev=END_TSO_QUEUE;
- t!=END_TSO_QUEUE && t!=tso;
- prev=t, t=t->link)
- /* nothing */ ;
- ASSERT(t==tso);
- /* now actually dequeue the tso */
- if (prev!=END_TSO_QUEUE) {
- ASSERT(run_queue_hd!=t);
- prev->link = t->link;
- } else {
- /* t is at beginning of thread queue */
- ASSERT(run_queue_hd==t);
- run_queue_hd = t->link;
- }
- /* t is at end of thread queue */
- if (t->link==END_TSO_QUEUE) {
- ASSERT(t==run_queue_tl);
- run_queue_tl = prev;
- } else {
- ASSERT(run_queue_tl!=t);
- }
- t->link = END_TSO_QUEUE;
- } else {
- /* take tso from the beginning of the queue; std concurrent code */
- t = run_queue_hd;
- if (t != END_TSO_QUEUE) {
- run_queue_hd = t->link;
- t->link = END_TSO_QUEUE;
- if (run_queue_hd == END_TSO_QUEUE) {
- run_queue_tl = END_TSO_QUEUE;
- }
- }
- }
- return t;
-}
-
-#endif /* 0 */
-
-//@node Garbage Collextion Routines, Blocking Queue Routines, Run queue code, Main scheduling code
-//@subsection Garbage Collextion Routines
-
/* ---------------------------------------------------------------------------
Where are the roots that we know about?
*/
void
-GetRoots(evac_fn evac)
+GetRoots( evac_fn evac )
{
#if defined(GRAN)
{
return dest;
}
-//@node Blocking Queue Routines, Exception Handling Routines, Garbage Collextion Routines, Main scheduling code
-//@subsection Blocking Queue Routines
-
/* ---------------------------------------------------------------------------
Wake up a queue that was blocked on some resource.
------------------------------------------------------------------------ */
}
#endif
-//@node Exception Handling Routines, Debugging Routines, Blocking Queue Routines, Main scheduling code
-//@subsection Exception Handling Routines
-
/* ---------------------------------------------------------------------------
Interrupt execution
- usually called inside a signal handler so it mustn't do anything fancy.
}
}
-//@node Debugging Routines, Index, Exception Handling Routines, Main scheduling code
-//@subsection Debugging Routines
-
-/* -----------------------------------------------------------------------------
+/* ----------------------------------------------------------------------------
* Debugging: why is a thread blocked
* [Also provides useful information when debugging threaded programs
* at the Haskell source code level, so enable outside of DEBUG. --sof 7/02]
- -------------------------------------------------------------------------- */
+ ------------------------------------------------------------------------- */
static
void
/*
Print a whole blocking queue attached to node (debugging only).
*/
-//@cindex print_bq
# if defined(PAR)
void
print_bq (StgClosure *node)
}
#endif /* DEBUG */
-
-
-//@node Index, , Debugging Routines, Main scheduling code
-//@subsection Index
-
-//@index
-//* StgMainThread:: @cindex\s-+StgMainThread
-//* awaken_blocked_queue:: @cindex\s-+awaken_blocked_queue
-//* blocked_queue_hd:: @cindex\s-+blocked_queue_hd
-//* blocked_queue_tl:: @cindex\s-+blocked_queue_tl
-//* context_switch:: @cindex\s-+context_switch
-//* createThread:: @cindex\s-+createThread
-//* gc_pending_cond:: @cindex\s-+gc_pending_cond
-//* initScheduler:: @cindex\s-+initScheduler
-//* interrupted:: @cindex\s-+interrupted
-//* next_thread_id:: @cindex\s-+next_thread_id
-//* print_bq:: @cindex\s-+print_bq
-//* run_queue_hd:: @cindex\s-+run_queue_hd
-//* run_queue_tl:: @cindex\s-+run_queue_tl
-//* sched_mutex:: @cindex\s-+sched_mutex
-//* schedule:: @cindex\s-+schedule
-//* take_off_run_queue:: @cindex\s-+take_off_run_queue
-//* term_mutex:: @cindex\s-+term_mutex
-//@end index
projects / ghc-hetmet.git / commitdiff