-/*
- * sgen-workers.c: Worker threads for parallel and concurrent GC.
+/**
+ * \file
+ * Worker threads for parallel and concurrent GC.
*
* Copyright 2001-2003 Ximian, Inc
* Copyright 2003-2010 Novell, Inc.
#include "mono/sgen/sgen-client.h"
static int workers_num;
+static int active_workers_num;
+static volatile gboolean started;
static volatile gboolean forced_stop;
static WorkerData *workers_data;
+static SgenWorkerCallback worker_init_cb;
+
+static SgenThreadPool pool_inst;
+static SgenThreadPool *pool; /* null if we're not using workers */
+
+/*
+ * When using multiple workers, we need to have the last worker
+ * enqueue the preclean jobs (if there are any). This lock ensures
+ * that when the last worker takes it, all the other workers have
+ * gracefully finished, so it can restart them.
+ */
+static mono_mutex_t finished_lock;
+static volatile gboolean workers_finished;
+static int worker_awakenings;
static SgenSectionGrayQueue workers_distribute_gray_queue;
static gboolean workers_distribute_gray_queue_inited;
*
* | from \ to | NOT WORKING | WORKING | WORK ENQUEUED |
* |--------------------+-------------+---------+---------------+
- * | NOT WORKING | - | - | main |
- * | WORKING | worker | - | main |
+ * | NOT WORKING | - | - | main / worker |
+ * | WORKING | worker | - | main / worker |
* | WORK ENQUEUED | - | worker | - |
*
* The WORK ENQUEUED state guarantees that the worker thread will inspect the queue again at
STATE_WORK_ENQUEUED
};
-typedef gint32 State;
+#define SGEN_WORKER_MIN_SECTIONS_SIGNAL 4
-static volatile State workers_state;
+typedef gint32 State;
static SgenObjectOperations * volatile idle_func_object_ops;
-static SgenThreadPoolJob * volatile preclean_job;
+static SgenObjectOperations *idle_func_object_ops_par, *idle_func_object_ops_nopar;
+/*
+ * finished_callback is called only when the workers finish work normally (when they
+ * are not forced to finish). The callback is used to enqueue preclean jobs.
+ */
+static volatile SgenWorkersFinishCallback finish_callback;
static guint64 stat_workers_num_finished;
static gboolean
-set_state (State old_state, State new_state)
+set_state (WorkerData *data, State old_state, State new_state)
{
SGEN_ASSERT (0, old_state != new_state, "Why are we transitioning to the same state?");
if (new_state == STATE_NOT_WORKING)
else if (new_state == STATE_WORKING)
SGEN_ASSERT (0, old_state == STATE_WORK_ENQUEUED, "We can only transition to WORKING from WORK ENQUEUED");
if (new_state == STATE_NOT_WORKING || new_state == STATE_WORKING)
- SGEN_ASSERT (6, sgen_thread_pool_is_thread_pool_thread (mono_native_thread_id_get ()), "Only the worker thread is allowed to transition to NOT_WORKING or WORKING");
+ SGEN_ASSERT (6, sgen_thread_pool_is_thread_pool_thread (pool, mono_native_thread_id_get ()), "Only the worker thread is allowed to transition to NOT_WORKING or WORKING");
- return InterlockedCompareExchange (&workers_state, new_state, old_state) == old_state;
+ return InterlockedCompareExchange (&data->state, new_state, old_state) == old_state;
}
static gboolean
static void
sgen_workers_ensure_awake (void)
{
- State old_state;
- gboolean did_set_state;
+ int i;
+ gboolean need_signal = FALSE;
- do {
- old_state = workers_state;
+ /*
+ * All workers are awaken, make sure we reset the parallel context.
+ * We call this function only when starting the workers so nobody is running,
+ * or when the last worker is enqueuing preclean work. In both cases we can't
+ * have a worker working using a nopar context, which means it is safe.
+ */
+ idle_func_object_ops = (active_workers_num > 1) ? idle_func_object_ops_par : idle_func_object_ops_nopar;
+ workers_finished = FALSE;
- if (old_state == STATE_WORK_ENQUEUED)
- break;
+ for (i = 0; i < active_workers_num; i++) {
+ State old_state;
+ gboolean did_set_state;
+
+ do {
+ old_state = workers_data [i].state;
+
+ if (old_state == STATE_WORK_ENQUEUED)
+ break;
- did_set_state = set_state (old_state, STATE_WORK_ENQUEUED);
- } while (!did_set_state);
+ did_set_state = set_state (&workers_data [i], old_state, STATE_WORK_ENQUEUED);
+ } while (!did_set_state);
- if (!state_is_working_or_enqueued (old_state))
- sgen_thread_pool_idle_signal ();
+ if (!state_is_working_or_enqueued (old_state))
+ need_signal = TRUE;
+ }
+
+ if (need_signal)
+ sgen_thread_pool_idle_signal (pool);
}
static void
-worker_try_finish (void)
+worker_try_finish (WorkerData *data)
{
State old_state;
+ int i, working = 0;
++stat_workers_num_finished;
+ mono_os_mutex_lock (&finished_lock);
+
+ for (i = 0; i < active_workers_num; i++) {
+ if (state_is_working_or_enqueued (workers_data [i].state))
+ working++;
+ }
+
+ if (working == 1) {
+ SgenWorkersFinishCallback callback = finish_callback;
+ SGEN_ASSERT (0, idle_func_object_ops == idle_func_object_ops_nopar, "Why are we finishing with parallel context");
+ /* We are the last one left. Enqueue preclean job if we have one and awake everybody */
+ SGEN_ASSERT (0, data->state != STATE_NOT_WORKING, "How did we get from doing idle work to NOT WORKING without setting it ourselves?");
+ if (callback) {
+ finish_callback = NULL;
+ callback ();
+ worker_awakenings = 0;
+ /* Make sure each worker has a chance of seeing the enqueued jobs */
+ sgen_workers_ensure_awake ();
+ SGEN_ASSERT (0, data->state == STATE_WORK_ENQUEUED, "Why did we fail to set our own state to ENQUEUED");
+ goto work_available;
+ }
+ }
+
do {
- old_state = workers_state;
+ old_state = data->state;
SGEN_ASSERT (0, old_state != STATE_NOT_WORKING, "How did we get from doing idle work to NOT WORKING without setting it ourselves?");
if (old_state == STATE_WORK_ENQUEUED)
- return;
+ goto work_available;
SGEN_ASSERT (0, old_state == STATE_WORKING, "What other possibility is there?");
+ } while (!set_state (data, old_state, STATE_NOT_WORKING));
+
+ /*
+ * If we are second to last to finish, we set the scan context to the non-parallel
+ * version so we can speed up the last worker. This helps us maintain same level
+ * of performance as non-parallel mode even if we fail to distribute work properly.
+ */
+ if (working == 2)
+ idle_func_object_ops = idle_func_object_ops_nopar;
- /* We are the last thread to go to sleep. */
- } while (!set_state (old_state, STATE_NOT_WORKING));
+ workers_finished = TRUE;
+ mono_os_mutex_unlock (&finished_lock);
binary_protocol_worker_finish (sgen_timestamp (), forced_stop);
+
+ sgen_gray_object_queue_trim_free_list (&data->private_gray_queue);
+ return;
+
+work_available:
+ mono_os_mutex_unlock (&finished_lock);
}
void
return;
}
- sgen_thread_pool_job_enqueue (job);
+ sgen_thread_pool_job_enqueue (pool, job);
}
-void
-sgen_workers_wait_for_jobs_finished (void)
+static gboolean
+workers_get_work (WorkerData *data)
{
- sgen_thread_pool_wait_for_all_jobs ();
- /*
- * If the idle task was never triggered or it finished before the last job did and
- * then didn't get triggered again, we might end up in the situation of having
- * something in the gray queue yet the idle task not working. The easiest way to
- * make sure this doesn't stay that way is to just trigger it again after all jobs
- * have finished.
- */
- sgen_workers_ensure_awake ();
+ SgenMajorCollector *major = sgen_get_major_collector ();
+ SgenMinorCollector *minor = sgen_get_minor_collector ();
+ GrayQueueSection *section;
+
+ g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
+ g_assert (major->is_concurrent || minor->is_parallel);
+
+ section = sgen_section_gray_queue_dequeue (&workers_distribute_gray_queue);
+ if (section) {
+ sgen_gray_object_enqueue_section (&data->private_gray_queue, section, major->is_parallel);
+ return TRUE;
+ }
+
+ /* Nobody to steal from */
+ g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
+ return FALSE;
}
static gboolean
-workers_get_work (WorkerData *data)
+workers_steal_work (WorkerData *data)
{
- SgenMajorCollector *major;
+ SgenMajorCollector *major = sgen_get_major_collector ();
+ SgenMinorCollector *minor = sgen_get_minor_collector ();
+ int generation = sgen_get_current_collection_generation ();
+ GrayQueueSection *section = NULL;
+ int i, current_worker;
+
+ if ((generation == GENERATION_OLD && !major->is_parallel) ||
+ (generation == GENERATION_NURSERY && !minor->is_parallel))
+ return FALSE;
+ /* If we're parallel, steal from other workers' private gray queues */
g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
- /* If we're concurrent, steal from the workers distribute gray queue. */
- major = sgen_get_major_collector ();
- if (major->is_concurrent) {
- GrayQueueSection *section = sgen_section_gray_queue_dequeue (&workers_distribute_gray_queue);
- if (section) {
- sgen_gray_object_enqueue_section (&data->private_gray_queue, section);
- return TRUE;
- }
+ current_worker = (int) (data - workers_data);
+
+ for (i = 1; i < active_workers_num && !section; i++) {
+ int steal_worker = (current_worker + i) % active_workers_num;
+ if (state_is_working_or_enqueued (workers_data [steal_worker].state))
+ section = sgen_gray_object_steal_section (&workers_data [steal_worker].private_gray_queue);
+ }
+
+ if (section) {
+ sgen_gray_object_enqueue_section (&data->private_gray_queue, section, TRUE);
+ return TRUE;
}
/* Nobody to steal from */
{
WorkerData *data = (WorkerData *)data_untyped;
SgenMajorCollector *major = sgen_get_major_collector ();
+ SgenMinorCollector *minor = sgen_get_minor_collector ();
sgen_client_thread_register_worker ();
- if (!major->is_concurrent)
+ if (!major->is_concurrent && !minor->is_parallel)
return;
init_private_gray_queue (data);
+
+ if (worker_init_cb)
+ worker_init_cb (data);
+}
+
+static gboolean
+continue_idle_func (void *data_untyped)
+{
+ if (data_untyped) {
+ WorkerData *data = (WorkerData *)data_untyped;
+ return state_is_working_or_enqueued (data->state);
+ } else {
+ /* Return if any of the threads is working */
+ return !sgen_workers_all_done ();
+ }
}
static gboolean
-continue_idle_func (void)
+should_work_func (void *data_untyped)
{
- return state_is_working_or_enqueued (workers_state);
+ WorkerData *data = (WorkerData*)data_untyped;
+ int current_worker = (int) (data - workers_data);
+
+ return started && current_worker < active_workers_num;
}
static void
{
WorkerData *data = (WorkerData *)data_untyped;
- SGEN_ASSERT (0, continue_idle_func (), "Why are we called when we're not supposed to work?");
- SGEN_ASSERT (0, sgen_concurrent_collection_in_progress (), "The worker should only mark in concurrent collections.");
+ SGEN_ASSERT (0, continue_idle_func (data_untyped), "Why are we called when we're not supposed to work?");
- if (workers_state == STATE_WORK_ENQUEUED) {
- set_state (STATE_WORK_ENQUEUED, STATE_WORKING);
- SGEN_ASSERT (0, workers_state != STATE_NOT_WORKING, "How did we get from WORK ENQUEUED to NOT WORKING?");
+ if (data->state == STATE_WORK_ENQUEUED) {
+ set_state (data, STATE_WORK_ENQUEUED, STATE_WORKING);
+ SGEN_ASSERT (0, data->state != STATE_NOT_WORKING, "How did we get from WORK ENQUEUED to NOT WORKING?");
}
- if (!forced_stop && (!sgen_gray_object_queue_is_empty (&data->private_gray_queue) || workers_get_work (data))) {
+ if (!forced_stop && (!sgen_gray_object_queue_is_empty (&data->private_gray_queue) || workers_get_work (data) || workers_steal_work (data))) {
ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (idle_func_object_ops, &data->private_gray_queue);
SGEN_ASSERT (0, !sgen_gray_object_queue_is_empty (&data->private_gray_queue), "How is our gray queue empty if we just got work?");
sgen_drain_gray_stack (ctx);
- } else {
- SgenThreadPoolJob *job = preclean_job;
- if (job) {
- sgen_thread_pool_job_enqueue (job);
- preclean_job = NULL;
- } else {
- worker_try_finish ();
+
+ if (data->private_gray_queue.num_sections >= SGEN_WORKER_MIN_SECTIONS_SIGNAL
+ && workers_finished && worker_awakenings < active_workers_num) {
+ /* We bound the number of worker awakenings just to be sure */
+ worker_awakenings++;
+ mono_os_mutex_lock (&finished_lock);
+ sgen_workers_ensure_awake ();
+ mono_os_mutex_unlock (&finished_lock);
}
+ } else {
+ worker_try_finish (data);
}
}
void
sgen_workers_init_distribute_gray_queue (void)
{
- SGEN_ASSERT (0, sgen_get_major_collector ()->is_concurrent,
+ SGEN_ASSERT (0, sgen_get_major_collector ()->is_concurrent || sgen_get_minor_collector ()->is_parallel,
"Why should we init the distribute gray queue if we don't need it?");
init_distribute_gray_queue ();
}
void
-sgen_workers_init (int num_workers)
+sgen_workers_init (int num_workers, SgenWorkerCallback callback)
{
int i;
- void **workers_data_ptrs = (void **)alloca(num_workers * sizeof(void *));
-
- if (!sgen_get_major_collector ()->is_concurrent) {
- sgen_thread_pool_init (num_workers, thread_pool_init_func, NULL, NULL, NULL);
- return;
- }
+ WorkerData **workers_data_ptrs = (WorkerData**)alloca(num_workers * sizeof(WorkerData*));
+ mono_os_mutex_init (&finished_lock);
//g_print ("initing %d workers\n", num_workers);
workers_num = num_workers;
+ active_workers_num = num_workers;
workers_data = (WorkerData *)sgen_alloc_internal_dynamic (sizeof (WorkerData) * num_workers, INTERNAL_MEM_WORKER_DATA, TRUE);
memset (workers_data, 0, sizeof (WorkerData) * num_workers);
init_distribute_gray_queue ();
- for (i = 0; i < workers_num; ++i)
- workers_data_ptrs [i] = (void *) &workers_data [i];
+ for (i = 0; i < num_workers; ++i)
+ workers_data_ptrs [i] = &workers_data [i];
- sgen_thread_pool_init (num_workers, thread_pool_init_func, marker_idle_func, continue_idle_func, workers_data_ptrs);
+ worker_init_cb = callback;
+
+ pool = &pool_inst;
+ sgen_thread_pool_init (pool, num_workers, thread_pool_init_func, marker_idle_func, continue_idle_func, should_work_func, (SgenThreadPoolData**)workers_data_ptrs);
mono_counters_register ("# workers finished", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_workers_num_finished);
}
+void
+sgen_workers_shutdown (void)
+{
+ if (pool)
+ sgen_thread_pool_shutdown (pool);
+}
+
void
sgen_workers_stop_all_workers (void)
{
- preclean_job = NULL;
+ finish_callback = NULL;
mono_memory_write_barrier ();
forced_stop = TRUE;
- sgen_thread_pool_wait_for_all_jobs ();
- sgen_thread_pool_idle_wait ();
- SGEN_ASSERT (0, workers_state == STATE_NOT_WORKING, "Can only signal enqueue work when in no work state");
+ sgen_thread_pool_wait_for_all_jobs (pool);
+ sgen_thread_pool_idle_wait (pool);
+ SGEN_ASSERT (0, sgen_workers_all_done (), "Can only signal enqueue work when in no work state");
+
+ started = FALSE;
+}
+
+void
+sgen_workers_set_num_active_workers (int num_workers)
+{
+ if (num_workers) {
+ SGEN_ASSERT (0, active_workers_num <= workers_num, "We can't start more workers than we initialized");
+ active_workers_num = num_workers;
+ } else {
+ active_workers_num = workers_num;
+ }
}
void
-sgen_workers_start_all_workers (SgenObjectOperations *object_ops, SgenThreadPoolJob *job)
+sgen_workers_start_all_workers (SgenObjectOperations *object_ops_nopar, SgenObjectOperations *object_ops_par, SgenWorkersFinishCallback callback)
{
+ SGEN_ASSERT (0, !started, "Why are we starting to work without finishing previous cycle");
+
+ idle_func_object_ops_par = object_ops_par;
+ idle_func_object_ops_nopar = object_ops_nopar;
forced_stop = FALSE;
- idle_func_object_ops = object_ops;
- preclean_job = job;
+ finish_callback = callback;
+ worker_awakenings = 0;
+ started = TRUE;
mono_memory_write_barrier ();
+ /*
+ * We expect workers to start finishing only after all of them were awaken.
+ * Otherwise we might think that we have fewer workers and use wrong context.
+ */
+ mono_os_mutex_lock (&finished_lock);
sgen_workers_ensure_awake ();
+ mono_os_mutex_unlock (&finished_lock);
}
void
{
int i;
- sgen_thread_pool_wait_for_all_jobs ();
- sgen_thread_pool_idle_wait ();
- SGEN_ASSERT (0, workers_state == STATE_NOT_WORKING, "Can only signal enqueue work when in no work state");
+ sgen_thread_pool_wait_for_all_jobs (pool);
+ sgen_thread_pool_idle_wait (pool);
+ SGEN_ASSERT (0, sgen_workers_all_done (), "Can only signal enqueue work when in no work state");
/* At this point all the workers have stopped. */
SGEN_ASSERT (0, sgen_section_gray_queue_is_empty (&workers_distribute_gray_queue), "Why is there still work left to do?");
- for (i = 0; i < workers_num; ++i)
+ for (i = 0; i < active_workers_num; ++i)
SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&workers_data [i].private_gray_queue), "Why is there still work left to do?");
+
+ started = FALSE;
}
/*
if (!sgen_section_gray_queue_is_empty (&workers_distribute_gray_queue))
return TRUE;
- for (i = 0; i < workers_num; ++i) {
+ for (i = 0; i < active_workers_num; ++i) {
if (!sgen_gray_object_queue_is_empty (&workers_data [i].private_gray_queue))
return TRUE;
}
gboolean
sgen_workers_all_done (void)
{
- return workers_state == STATE_NOT_WORKING;
+ int i;
+
+ for (i = 0; i < active_workers_num; i++) {
+ if (state_is_working_or_enqueued (workers_data [i].state))
+ return FALSE;
+ }
+ return TRUE;
}
/* Must only be used for debugging */
gboolean
sgen_workers_are_working (void)
{
- return state_is_working_or_enqueued (workers_state);
+ return !sgen_workers_all_done ();
}
void
}
void
-sgen_workers_take_from_queue_and_awake (SgenGrayQueue *queue)
+sgen_workers_take_from_queue (SgenGrayQueue *queue)
{
- gboolean wake = FALSE;
+ sgen_gray_object_spread (queue, sgen_workers_get_job_split_count ());
for (;;) {
GrayQueueSection *section = sgen_gray_object_dequeue_section (queue);
if (!section)
break;
sgen_section_gray_queue_enqueue (&workers_distribute_gray_queue, section);
- wake = TRUE;
}
- if (wake) {
- SGEN_ASSERT (0, sgen_concurrent_collection_in_progress (), "Why is there work to take when there's no concurrent collection in progress?");
- sgen_workers_ensure_awake ();
- }
+ SGEN_ASSERT (0, !sgen_workers_are_working (), "We should fully populate the distribute gray queue before we start the workers");
+}
+
+SgenObjectOperations*
+sgen_workers_get_idle_func_object_ops (void)
+{
+ return (idle_func_object_ops_par) ? idle_func_object_ops_par : idle_func_object_ops_nopar;
+}
+
+/*
+ * If we have a single worker, splitting into multiple jobs makes no sense. With
+ * more than one worker, we split into a larger number of jobs so that, in case
+ * the work load is uneven, a worker that finished quickly can take up more jobs
+ * than another one.
+ */
+int
+sgen_workers_get_job_split_count (void)
+{
+ return (active_workers_num > 1) ? active_workers_num * 4 : 1;
+}
+
+void
+sgen_workers_foreach (SgenWorkerCallback callback)
+{
+ int i;
+
+ for (i = 0; i < workers_num; i++)
+ callback (&workers_data [i]);
+}
+
+gboolean
+sgen_workers_is_worker_thread (MonoNativeThreadId id)
+{
+ if (!pool)
+ return FALSE;
+ return sgen_thread_pool_is_thread_pool_thread (pool, id);
}
#endif
projects / mono.git / blobdiff