1 /* -----------------------------------------------------------------------------
3 * (c) The GHC Team 2001-2005
5 * The task manager subsystem. Tasks execute STG code, with this
6 * module providing the API which the Scheduler uses to control their
7 * creation and destruction.
9 * -------------------------------------------------------------------------*/
13 #include "OSThreads.h"
15 #include "Capability.h"
26 // Task lists and global counters.
27 // Locks required: sched_mutex.
28 Task *all_tasks = NULL;
29 static Task *task_free_list = NULL; // singly-linked
31 static nat tasksRunning;
32 static nat workerCount;
34 /* -----------------------------------------------------------------------------
35 * Remembering the current thread's Task
36 * -------------------------------------------------------------------------- */
38 // A thread-local-storage key that we can use to get access to the
39 // current thread's Task structure.
40 #if defined(THREADED_RTS)
41 ThreadLocalKey currentTaskKey;
46 /* -----------------------------------------------------------------------------
47 * Rest of the Task API
48 * -------------------------------------------------------------------------- */
51 initTaskManager (void)
53 static int initialized = 0;
60 #if defined(THREADED_RTS)
61 newThreadLocalKey(¤tTaskKey);
68 stopTaskManager (void)
72 debugTrace(DEBUG_sched,
73 "stopping task manager, %d tasks still running",
76 ACQUIRE_LOCK(&sched_mutex);
77 for (task = task_free_list; task != NULL; task = next) {
81 task_free_list = NULL;
82 RELEASE_LOCK(&sched_mutex);
89 #if defined(THREADED_RTS)
90 Ticks currentElapsedTime, currentUserTime;
94 task = stgMallocBytes(sizeof(Task), "newTask");
97 task->stopped = rtsFalse;
98 task->suspended_tso = NULL;
100 task->stat = NoStatus;
103 #if defined(THREADED_RTS)
104 initCondition(&task->cond);
105 initMutex(&task->lock);
106 task->wakeup = rtsFalse;
109 #if defined(THREADED_RTS)
110 currentUserTime = getThreadCPUTime();
111 currentElapsedTime = getProcessElapsedTime();
116 task->muttimestart = currentUserTime;
117 task->elapsedtimestart = currentElapsedTime;
122 task->return_link = NULL;
124 task->all_link = all_tasks;
138 ASSERT_LOCK_HELD(&sched_mutex);
139 if (task_free_list == NULL) {
142 task = task_free_list;
143 task_free_list = task->next;
146 task->stopped = rtsFalse;
148 #if defined(THREADED_RTS)
149 task->id = osThreadId();
151 ASSERT(task->cap == NULL);
157 debugTrace(DEBUG_sched, "new task (taskCount: %d)", taskCount);
162 boundTaskExiting (Task *task)
164 task->stopped = rtsTrue;
167 #if defined(THREADED_RTS)
168 ASSERT(osThreadId() == task->id);
170 ASSERT(myTask() == task);
171 setMyTask(task->prev_stack);
175 // sadly, we need a lock around the free task list. Todo: eliminate.
176 ACQUIRE_LOCK(&sched_mutex);
177 task->next = task_free_list;
178 task_free_list = task;
179 RELEASE_LOCK(&sched_mutex);
181 debugTrace(DEBUG_sched, "task exiting");
185 #define TASK_ID(t) (t)->id
187 #define TASK_ID(t) (t)
191 discardTask (Task *task)
193 ASSERT_LOCK_HELD(&sched_mutex);
194 if (!task->stopped) {
195 debugTrace(DEBUG_sched, "discarding task %ld", (long)TASK_ID(task));
198 task->stopped = rtsTrue;
200 task->next = task_free_list;
201 task_free_list = task;
206 taskTimeStamp (Task *task USED_IF_THREADS)
208 #if defined(THREADED_RTS)
209 Ticks currentElapsedTime, currentUserTime, elapsedGCTime;
211 currentUserTime = getThreadCPUTime();
212 currentElapsedTime = getProcessElapsedTime();
214 // XXX this is wrong; we want elapsed GC time since the
216 elapsedGCTime = stat_getElapsedGCTime();
219 currentUserTime - task->muttimestart - task->gc_time;
221 currentElapsedTime - task->elapsedtimestart - elapsedGCTime;
223 if (task->mut_time < 0) { task->mut_time = 0; }
224 if (task->mut_etime < 0) { task->mut_etime = 0; }
229 workerTaskStop (Task *task)
231 #if defined(THREADED_RTS)
234 ASSERT(task->id == id);
235 ASSERT(myTask() == task);
239 task->stopped = rtsTrue;
244 resetTaskManagerAfterFork (void)
250 #if defined(THREADED_RTS)
253 startWorkerTask (Capability *cap,
254 void OSThreadProcAttr (*taskStart)(Task *task))
262 // A worker always gets a fresh Task structure.
267 // The lock here is to synchronise with taskStart(), to make sure
268 // that we have finished setting up the Task structure before the
269 // worker thread reads it.
270 ACQUIRE_LOCK(&task->lock);
274 // Give the capability directly to the worker; we can't let anyone
275 // else get in, because the new worker Task has nowhere to go to
276 // sleep so that it could be woken up again.
277 ASSERT_LOCK_HELD(&cap->lock);
278 cap->running_task = task;
280 r = createOSThread(&tid, (OSThreadProc *)taskStart, task);
282 barf("startTask: Can't create new task");
285 debugTrace(DEBUG_sched, "new worker task (taskCount: %d)", taskCount);
289 // ok, finished with the Task struct.
290 RELEASE_LOCK(&task->lock);
293 #endif /* THREADED_RTS */
297 static void *taskId(Task *task)
300 return (void *)task->id;
306 void printAllTasks(void);
312 for (task = all_tasks; task != NULL; task = task->all_link) {
313 debugBelch("task %p is %s, ", taskId(task), task->stopped ? "stopped" : "alive");
314 if (!task->stopped) {
316 debugBelch("on capability %d, ", task->cap->no);
319 debugBelch("bound to thread %lu", (unsigned long)task->tso->id);
321 debugBelch("worker");