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"
27 // Task lists and global counters.
28 // Locks required: sched_mutex.
29 Task *all_tasks = NULL;
30 static Task *task_free_list = NULL; // singly-linked
32 static nat tasksRunning;
33 static nat workerCount;
35 /* -----------------------------------------------------------------------------
36 * Remembering the current thread's Task
37 * -------------------------------------------------------------------------- */
39 // A thread-local-storage key that we can use to get access to the
40 // current thread's Task structure.
41 #if defined(THREADED_RTS)
42 ThreadLocalKey currentTaskKey;
47 /* -----------------------------------------------------------------------------
48 * Rest of the Task API
49 * -------------------------------------------------------------------------- */
52 initTaskManager (void)
54 static int initialized = 0;
61 #if defined(THREADED_RTS)
62 newThreadLocalKey(¤tTaskKey);
69 stopTaskManager (void)
73 debugTrace(DEBUG_sched,
74 "stopping task manager, %d tasks still running",
77 ACQUIRE_LOCK(&sched_mutex);
78 for (task = task_free_list; task != NULL; task = next) {
80 #if defined(THREADED_RTS)
81 closeCondition(&task->cond);
82 closeMutex(&task->lock);
86 task_free_list = NULL;
87 RELEASE_LOCK(&sched_mutex);
94 #if defined(THREADED_RTS)
95 Ticks currentElapsedTime, currentUserTime;
99 task = stgMallocBytes(sizeof(Task), "newTask");
102 task->stopped = rtsFalse;
103 task->suspended_tso = NULL;
105 task->stat = NoStatus;
108 #if defined(THREADED_RTS)
109 initCondition(&task->cond);
110 initMutex(&task->lock);
111 task->wakeup = rtsFalse;
114 #if defined(THREADED_RTS)
115 currentUserTime = getThreadCPUTime();
116 currentElapsedTime = getProcessElapsedTime();
121 task->muttimestart = currentUserTime;
122 task->elapsedtimestart = currentElapsedTime;
127 task->return_link = NULL;
129 task->all_link = all_tasks;
143 ASSERT_LOCK_HELD(&sched_mutex);
144 if (task_free_list == NULL) {
147 task = task_free_list;
148 task_free_list = task->next;
151 task->stopped = rtsFalse;
153 #if defined(THREADED_RTS)
154 task->id = osThreadId();
156 ASSERT(task->cap == NULL);
162 debugTrace(DEBUG_sched, "new task (taskCount: %d)", taskCount);
167 boundTaskExiting (Task *task)
169 task->stopped = rtsTrue;
172 #if defined(THREADED_RTS)
173 ASSERT(osThreadId() == task->id);
175 ASSERT(myTask() == task);
176 setMyTask(task->prev_stack);
180 // sadly, we need a lock around the free task list. Todo: eliminate.
181 ACQUIRE_LOCK(&sched_mutex);
182 task->next = task_free_list;
183 task_free_list = task;
184 RELEASE_LOCK(&sched_mutex);
186 debugTrace(DEBUG_sched, "task exiting");
190 #define TASK_ID(t) (t)->id
192 #define TASK_ID(t) (t)
196 discardTask (Task *task)
198 ASSERT_LOCK_HELD(&sched_mutex);
199 if (!task->stopped) {
200 debugTrace(DEBUG_sched, "discarding task %ld", (long)TASK_ID(task));
203 task->stopped = rtsTrue;
205 task->next = task_free_list;
206 task_free_list = task;
211 taskTimeStamp (Task *task USED_IF_THREADS)
213 #if defined(THREADED_RTS)
214 Ticks currentElapsedTime, currentUserTime, elapsedGCTime;
216 currentUserTime = getThreadCPUTime();
217 currentElapsedTime = getProcessElapsedTime();
219 // XXX this is wrong; we want elapsed GC time since the
221 elapsedGCTime = stat_getElapsedGCTime();
224 currentUserTime - task->muttimestart - task->gc_time;
226 currentElapsedTime - task->elapsedtimestart - elapsedGCTime;
228 if (task->mut_time < 0) { task->mut_time = 0; }
229 if (task->mut_etime < 0) { task->mut_etime = 0; }
234 workerTaskStop (Task *task)
236 #if defined(THREADED_RTS)
239 ASSERT(task->id == id);
240 ASSERT(myTask() == task);
244 task->stopped = rtsTrue;
249 resetTaskManagerAfterFork (void)
255 #if defined(THREADED_RTS)
258 startWorkerTask (Capability *cap,
259 void OSThreadProcAttr (*taskStart)(Task *task))
267 // A worker always gets a fresh Task structure.
272 // The lock here is to synchronise with taskStart(), to make sure
273 // that we have finished setting up the Task structure before the
274 // worker thread reads it.
275 ACQUIRE_LOCK(&task->lock);
279 // Give the capability directly to the worker; we can't let anyone
280 // else get in, because the new worker Task has nowhere to go to
281 // sleep so that it could be woken up again.
282 ASSERT_LOCK_HELD(&cap->lock);
283 cap->running_task = task;
285 r = createOSThread(&tid, (OSThreadProc *)taskStart, task);
287 sysErrorBelch("failed to create OS thread");
288 stg_exit(EXIT_FAILURE);
291 debugTrace(DEBUG_sched, "new worker task (taskCount: %d)", taskCount);
295 // ok, finished with the Task struct.
296 RELEASE_LOCK(&task->lock);
299 #endif /* THREADED_RTS */
303 static void *taskId(Task *task)
306 return (void *)task->id;
312 void printAllTasks(void);
318 for (task = all_tasks; task != NULL; task = task->all_link) {
319 debugBelch("task %p is %s, ", taskId(task), task->stopped ? "stopped" : "alive");
320 if (!task->stopped) {
322 debugBelch("on capability %d, ", task->cap->no);
325 debugBelch("bound to thread %lu", (unsigned long)task->tso->id);
327 debugBelch("worker");