mono/sgen/sgen-workers.c

   1 /**
   2  * \file
   3  * Worker threads for parallel and concurrent GC.
   4  *
   5  * Copyright 2001-2003 Ximian, Inc
   6  * Copyright 2003-2010 Novell, Inc.
   7  * Copyright (C) 2012 Xamarin Inc
   8  *
   9  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  10  */
  11
  12 #include "config.h"
  13 #ifdef HAVE_SGEN_GC
  14
  15 #include <string.h>
  16
  17 #include "mono/sgen/sgen-gc.h"
  18 #include "mono/sgen/sgen-workers.h"
  19 #include "mono/sgen/sgen-thread-pool.h"
  20 #include "mono/utils/mono-membar.h"
  21 #include "mono/sgen/sgen-client.h"
  22
  23 static WorkerContext worker_contexts [GENERATION_MAX];
  24
  25 /*
  26  * Allowed transitions:
  27  *
  28  * | from \ to          | NOT WORKING | WORKING | WORK ENQUEUED |
  29  * |--------------------+-------------+---------+---------------+
  30  * | NOT WORKING        | -           | -       | main / worker |
  31  * | WORKING            | worker      | -       | main / worker |
  32  * | WORK ENQUEUED      | -           | worker  | -             |
  33  *
  34  * The WORK ENQUEUED state guarantees that the worker thread will inspect the queue again at
  35  * least once.  Only after looking at the queue will it go back to WORKING, and then,
  36  * eventually, to NOT WORKING.  After enqueuing work the main thread transitions the state
  37  * to WORK ENQUEUED.  Signalling the worker thread to wake up is only necessary if the old
  38  * state was NOT WORKING.
  39  */
  40
  41 enum {
  42         STATE_NOT_WORKING,
  43         STATE_WORKING,
  44         STATE_WORK_ENQUEUED
  45 };
  46
  47 #define SGEN_WORKER_MIN_SECTIONS_SIGNAL 4
  48
  49 static guint64 stat_workers_num_finished;
  50
  51 static gboolean
  52 set_state (WorkerData *data, State old_state, State new_state)
  53 {
  54         SGEN_ASSERT (0, old_state != new_state, "Why are we transitioning to the same state?");
  55         if (new_state == STATE_NOT_WORKING)
  56                 SGEN_ASSERT (0, old_state == STATE_WORKING, "We can only transition to NOT WORKING from WORKING");
  57         else if (new_state == STATE_WORKING)
  58                 SGEN_ASSERT (0, old_state == STATE_WORK_ENQUEUED, "We can only transition to WORKING from WORK ENQUEUED");
  59
  60         return InterlockedCompareExchange (&data->state, new_state, old_state) == old_state;
  61 }
  62
  63 static gboolean
  64 state_is_working_or_enqueued (State state)
  65 {
  66         return state == STATE_WORKING || state == STATE_WORK_ENQUEUED;
  67 }
  68
  69 static void
  70 sgen_workers_ensure_awake (WorkerContext *context)
  71 {
  72         int i;
  73         gboolean need_signal = FALSE;
  74
  75         /*
  76          * All workers are awaken, make sure we reset the parallel context.
  77          * We call this function only when starting the workers so nobody is running,
  78          * or when the last worker is enqueuing preclean work. In both cases we can't
  79          * have a worker working using a nopar context, which means it is safe.
  80          */
  81         context->idle_func_object_ops = (context->active_workers_num > 1) ? context->idle_func_object_ops_par : context->idle_func_object_ops_nopar;
  82         context->workers_finished = FALSE;
  83
  84         for (i = 0; i < context->active_workers_num; i++) {
  85                 State old_state;
  86                 gboolean did_set_state;
  87
  88                 do {
  89                         old_state = context->workers_data [i].state;
  90
  91                         if (old_state == STATE_WORK_ENQUEUED)
  92                                 break;
  93
  94                         did_set_state = set_state (&context->workers_data [i], old_state, STATE_WORK_ENQUEUED);
  95
  96                         if (did_set_state && old_state == STATE_NOT_WORKING)
  97                                 context->workers_data [i].last_start = sgen_timestamp ();
  98                 } while (!did_set_state);
  99
 100                 if (!state_is_working_or_enqueued (old_state))
 101                         need_signal = TRUE;
 102         }
 103
 104         if (need_signal)
 105                 sgen_thread_pool_idle_signal (context->thread_pool_context);
 106 }
 107
 108 static void
 109 worker_try_finish (WorkerData *data)
 110 {
 111         State old_state;
 112         int i, working = 0;
 113         WorkerContext *context = data->context;
 114         gint64 last_start = data->last_start;
 115
 116         ++stat_workers_num_finished;
 117
 118         mono_os_mutex_lock (&context->finished_lock);
 119
 120         for (i = 0; i < context->active_workers_num; i++) {
 121                 if (state_is_working_or_enqueued (context->workers_data [i].state))
 122                         working++;
 123         }
 124
 125         if (working == 1) {
 126                 SgenWorkersFinishCallback callback = context->finish_callback;
 127                 SGEN_ASSERT (0, context->idle_func_object_ops == context->idle_func_object_ops_nopar, "Why are we finishing with parallel context");
 128                 /* We are the last one left. Enqueue preclean job if we have one and awake everybody */
 129                 SGEN_ASSERT (0, data->state != STATE_NOT_WORKING, "How did we get from doing idle work to NOT WORKING without setting it ourselves?");
 130                 if (callback) {
 131                         context->finish_callback = NULL;
 132                         callback ();
 133                         context->worker_awakenings = 0;
 134                         /* Make sure each worker has a chance of seeing the enqueued jobs */
 135                         sgen_workers_ensure_awake (context);
 136                         SGEN_ASSERT (0, data->state == STATE_WORK_ENQUEUED, "Why did we fail to set our own state to ENQUEUED");
 137
 138                         /*
 139                          * Log to be able to get the duration of normal concurrent M&S phase.
 140                          * Worker indexes are 1 based, since 0 is logically considered gc thread.
 141                          */
 142                         binary_protocol_worker_finish_stats (data - &context->workers_data [0] + 1, context->generation, context->forced_stop, data->major_scan_time, data->los_scan_time, data->total_time + sgen_timestamp () - last_start);
 143                         goto work_available;
 144                 }
 145         }
 146
 147         do {
 148                 old_state = data->state;
 149
 150                 SGEN_ASSERT (0, old_state != STATE_NOT_WORKING, "How did we get from doing idle work to NOT WORKING without setting it ourselves?");
 151                 if (old_state == STATE_WORK_ENQUEUED)
 152                         goto work_available;
 153                 SGEN_ASSERT (0, old_state == STATE_WORKING, "What other possibility is there?");
 154         } while (!set_state (data, old_state, STATE_NOT_WORKING));
 155
 156         /*
 157          * If we are second to last to finish, we set the scan context to the non-parallel
 158          * version so we can speed up the last worker. This helps us maintain same level
 159          * of performance as non-parallel mode even if we fail to distribute work properly.
 160          */
 161         if (working == 2)
 162                 context->idle_func_object_ops = context->idle_func_object_ops_nopar;
 163
 164         context->workers_finished = TRUE;
 165         mono_os_mutex_unlock (&context->finished_lock);
 166
 167         data->total_time += (sgen_timestamp () - last_start);
 168         binary_protocol_worker_finish_stats (data - &context->workers_data [0] + 1, context->generation, context->forced_stop, data->major_scan_time, data->los_scan_time, data->total_time);
 169
 170         sgen_gray_object_queue_trim_free_list (&data->private_gray_queue);
 171         return;
 172
 173 work_available:
 174         mono_os_mutex_unlock (&context->finished_lock);
 175 }
 176
 177 void
 178 sgen_workers_enqueue_job (int generation, SgenThreadPoolJob *job, gboolean enqueue)
 179 {
 180         if (!enqueue) {
 181                 job->func (NULL, job);
 182                 sgen_thread_pool_job_free (job);
 183                 return;
 184         }
 185
 186         sgen_thread_pool_job_enqueue (worker_contexts [generation].thread_pool_context, job);
 187 }
 188
 189 static gboolean
 190 workers_get_work (WorkerData *data)
 191 {
 192         SgenMajorCollector *major = sgen_get_major_collector ();
 193         SgenMinorCollector *minor = sgen_get_minor_collector ();
 194         GrayQueueSection *section;
 195
 196         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 197         g_assert (major->is_concurrent || minor->is_parallel);
 198
 199         section = sgen_section_gray_queue_dequeue (&data->context->workers_distribute_gray_queue);
 200         if (section) {
 201                 sgen_gray_object_enqueue_section (&data->private_gray_queue, section, major->is_parallel);
 202                 return TRUE;
 203         }
 204
 205         /* Nobody to steal from */
 206         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 207         return FALSE;
 208 }
 209
 210 static gboolean
 211 workers_steal_work (WorkerData *data)
 212 {
 213         SgenMajorCollector *major = sgen_get_major_collector ();
 214         SgenMinorCollector *minor = sgen_get_minor_collector ();
 215         int generation = sgen_get_current_collection_generation ();
 216         GrayQueueSection *section = NULL;
 217         WorkerContext *context = data->context;
 218         int i, current_worker;
 219
 220         if ((generation == GENERATION_OLD && !major->is_parallel) ||
 221                         (generation == GENERATION_NURSERY && !minor->is_parallel))
 222                 return FALSE;
 223
 224         /* If we're parallel, steal from other workers' private gray queues  */
 225         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 226
 227         current_worker = (int) (data - context->workers_data);
 228
 229         for (i = 1; i < context->active_workers_num && !section; i++) {
 230                 int steal_worker = (current_worker + i) % context->active_workers_num;
 231                 if (state_is_working_or_enqueued (context->workers_data [steal_worker].state))
 232                         section = sgen_gray_object_steal_section (&context->workers_data [steal_worker].private_gray_queue);
 233         }
 234
 235         if (section) {
 236                 sgen_gray_object_enqueue_section (&data->private_gray_queue, section, TRUE);
 237                 return TRUE;
 238         }
 239
 240         /* Nobody to steal from */
 241         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 242         return FALSE;
 243 }
 244
 245 static void
 246 concurrent_enqueue_check (GCObject *obj)
 247 {
 248         g_assert (sgen_concurrent_collection_in_progress ());
 249         g_assert (!sgen_ptr_in_nursery (obj));
 250         g_assert (SGEN_LOAD_VTABLE (obj));
 251 }
 252
 253 static void
 254 init_private_gray_queue (WorkerData *data)
 255 {
 256         sgen_gray_object_queue_init (&data->private_gray_queue,
 257                         sgen_get_major_collector ()->is_concurrent ? concurrent_enqueue_check : NULL,
 258                         FALSE);
 259 }
 260
 261 static void
 262 thread_pool_init_func (void *data_untyped)
 263 {
 264         WorkerData *data = (WorkerData *)data_untyped;
 265         SgenMajorCollector *major = sgen_get_major_collector ();
 266         SgenMinorCollector *minor = sgen_get_minor_collector ();
 267
 268         if (!major->is_concurrent && !minor->is_parallel)
 269                 return;
 270
 271         init_private_gray_queue (data);
 272
 273         /* Separate WorkerData for same thread share free_block_lists */
 274         if (major->is_parallel || minor->is_parallel)
 275                 major->init_block_free_lists (&data->free_block_lists);
 276 }
 277
 278 static gboolean
 279 sgen_workers_are_working (WorkerContext *context)
 280 {
 281         int i;
 282
 283         for (i = 0; i < context->active_workers_num; i++) {
 284                 if (state_is_working_or_enqueued (context->workers_data [i].state))
 285                         return TRUE;
 286         }
 287         return FALSE;
 288 }
 289
 290 static gboolean
 291 continue_idle_func (void *data_untyped, int thread_pool_context)
 292 {
 293         if (data_untyped)
 294                 return state_is_working_or_enqueued (((WorkerData*)data_untyped)->state);
 295
 296         /* Return if any of the threads is working in the context */
 297         if (worker_contexts [GENERATION_NURSERY].workers_num && worker_contexts [GENERATION_NURSERY].thread_pool_context == thread_pool_context)
 298                 return sgen_workers_are_working (&worker_contexts [GENERATION_NURSERY]);
 299         if (worker_contexts [GENERATION_OLD].workers_num && worker_contexts [GENERATION_OLD].thread_pool_context == thread_pool_context)
 300                 return sgen_workers_are_working (&worker_contexts [GENERATION_OLD]);
 301
 302         g_assert_not_reached ();
 303         return FALSE;
 304 }
 305
 306 static gboolean
 307 should_work_func (void *data_untyped)
 308 {
 309         WorkerData *data = (WorkerData*)data_untyped;
 310         WorkerContext *context = data->context;
 311         int current_worker = (int) (data - context->workers_data);
 312
 313         return context->started && current_worker < context->active_workers_num && state_is_working_or_enqueued (data->state);
 314 }
 315
 316 static void
 317 marker_idle_func (void *data_untyped)
 318 {
 319         WorkerData *data = (WorkerData *)data_untyped;
 320         WorkerContext *context = data->context;
 321
 322         SGEN_ASSERT (0, continue_idle_func (data_untyped, context->thread_pool_context), "Why are we called when we're not supposed to work?");
 323
 324         if (data->state == STATE_WORK_ENQUEUED) {
 325                 set_state (data, STATE_WORK_ENQUEUED, STATE_WORKING);
 326                 SGEN_ASSERT (0, data->state != STATE_NOT_WORKING, "How did we get from WORK ENQUEUED to NOT WORKING?");
 327         }
 328
 329         if (!context->forced_stop && (!sgen_gray_object_queue_is_empty (&data->private_gray_queue) || workers_get_work (data) || workers_steal_work (data))) {
 330                 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (context->idle_func_object_ops, &data->private_gray_queue);
 331
 332                 SGEN_ASSERT (0, !sgen_gray_object_queue_is_empty (&data->private_gray_queue), "How is our gray queue empty if we just got work?");
 333
 334                 sgen_drain_gray_stack (ctx);
 335
 336                 if (data->private_gray_queue.num_sections >= SGEN_WORKER_MIN_SECTIONS_SIGNAL
 337                                 && context->workers_finished && context->worker_awakenings < context->active_workers_num) {
 338                         /* We bound the number of worker awakenings just to be sure */
 339                         context->worker_awakenings++;
 340                         mono_os_mutex_lock (&context->finished_lock);
 341                         sgen_workers_ensure_awake (context);
 342                         mono_os_mutex_unlock (&context->finished_lock);
 343                 }
 344         } else {
 345                 worker_try_finish (data);
 346         }
 347 }
 348
 349 static void
 350 init_distribute_gray_queue (WorkerContext *context)
 351 {
 352         sgen_section_gray_queue_init (&context->workers_distribute_gray_queue, TRUE,
 353                         sgen_get_major_collector ()->is_concurrent ? concurrent_enqueue_check : NULL);
 354 }
 355
 356 void
 357 sgen_workers_create_context (int generation, int num_workers)
 358 {
 359         static gboolean stat_inited = FALSE;
 360         int i;
 361         WorkerData **workers_data_ptrs = (WorkerData**)sgen_alloc_internal_dynamic (num_workers * sizeof(WorkerData*), INTERNAL_MEM_WORKER_DATA, TRUE);
 362         WorkerContext *context = &worker_contexts [generation];
 363
 364         SGEN_ASSERT (0, !context->workers_num, "We can't init the worker context for a generation twice");
 365
 366         mono_os_mutex_init (&context->finished_lock);
 367
 368         context->generation = generation;
 369         context->workers_num = num_workers;
 370         context->active_workers_num = num_workers;
 371
 372         context->workers_data = (WorkerData *)sgen_alloc_internal_dynamic (sizeof (WorkerData) * num_workers, INTERNAL_MEM_WORKER_DATA, TRUE);
 373         memset (context->workers_data, 0, sizeof (WorkerData) * num_workers);
 374
 375         init_distribute_gray_queue (context);
 376
 377         for (i = 0; i < num_workers; ++i) {
 378                 workers_data_ptrs [i] = &context->workers_data [i];
 379                 context->workers_data [i].context = context;
 380         }
 381
 382         context->thread_pool_context = sgen_thread_pool_create_context (num_workers, thread_pool_init_func, marker_idle_func, continue_idle_func, should_work_func, (void**)workers_data_ptrs);
 383
 384         if (!stat_inited) {
 385                 mono_counters_register ("# workers finished", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_workers_num_finished);
 386                 stat_inited = TRUE;
 387         }
 388 }
 389
 390 /* This is called with thread pool lock so no context switch can happen */
 391 static gboolean
 392 continue_idle_wait (int calling_context, int *threads_context)
 393 {
 394         WorkerContext *context;
 395         int i;
 396
 397         if (worker_contexts [GENERATION_OLD].workers_num && calling_context == worker_contexts [GENERATION_OLD].thread_pool_context)
 398                 context = &worker_contexts [GENERATION_OLD];
 399         else if (worker_contexts [GENERATION_NURSERY].workers_num && calling_context == worker_contexts [GENERATION_NURSERY].thread_pool_context)
 400                 context = &worker_contexts [GENERATION_NURSERY];
 401         else
 402                 g_assert_not_reached ();
 403
 404         /*
 405          * We assume there are no pending jobs, since this is called only after
 406          * we waited for all the jobs.
 407          */
 408         for (i = 0; i < context->active_workers_num; i++) {
 409                 if (threads_context [i] == calling_context)
 410                         return TRUE;
 411         }
 412
 413         if (sgen_workers_have_idle_work (context->generation) && !context->forced_stop)
 414                 return TRUE;
 415
 416         /*
 417          * At this point there are no jobs to be done, and no objects to be scanned
 418          * in the gray queues. We can simply asynchronously finish all the workers
 419          * from the context that were not finished already (due to being stuck working
 420          * in another context)
 421          */
 422
 423         for (i = 0; i < context->active_workers_num; i++) {
 424                 if (context->workers_data [i].state == STATE_WORK_ENQUEUED)
 425                         set_state (&context->workers_data [i], STATE_WORK_ENQUEUED, STATE_WORKING);
 426                 if (context->workers_data [i].state == STATE_WORKING)
 427                         worker_try_finish (&context->workers_data [i]);
 428         }
 429
 430         return FALSE;
 431 }
 432
 433
 434 void
 435 sgen_workers_stop_all_workers (int generation)
 436 {
 437         WorkerContext *context = &worker_contexts [generation];
 438
 439         mono_os_mutex_lock (&context->finished_lock);
 440         context->finish_callback = NULL;
 441         mono_os_mutex_unlock (&context->finished_lock);
 442
 443         context->forced_stop = TRUE;
 444
 445         sgen_thread_pool_wait_for_all_jobs (context->thread_pool_context);
 446         sgen_thread_pool_idle_wait (context->thread_pool_context, continue_idle_wait);
 447         SGEN_ASSERT (0, !sgen_workers_are_working (context), "Can only signal enqueue work when in no work state");
 448
 449         context->started = FALSE;
 450 }
 451
 452 void
 453 sgen_workers_set_num_active_workers (int generation, int num_workers)
 454 {
 455         WorkerContext *context = &worker_contexts [generation];
 456         if (num_workers) {
 457                 SGEN_ASSERT (0, num_workers <= context->workers_num, "We can't start more workers than we initialized");
 458                 context->active_workers_num = num_workers;
 459         } else {
 460                 context->active_workers_num = context->workers_num;
 461         }
 462 }
 463
 464 void
 465 sgen_workers_start_all_workers (int generation, SgenObjectOperations *object_ops_nopar, SgenObjectOperations *object_ops_par, SgenWorkersFinishCallback callback)
 466 {
 467         WorkerContext *context = &worker_contexts [generation];
 468         int i;
 469         SGEN_ASSERT (0, !context->started, "Why are we starting to work without finishing previous cycle");
 470
 471         context->idle_func_object_ops_par = object_ops_par;
 472         context->idle_func_object_ops_nopar = object_ops_nopar;
 473         context->forced_stop = FALSE;
 474         context->finish_callback = callback;
 475         context->worker_awakenings = 0;
 476         context->started = TRUE;
 477
 478         for (i = 0; i < context->active_workers_num; i++) {
 479                 context->workers_data [i].major_scan_time = 0;
 480                 context->workers_data [i].los_scan_time = 0;
 481                 context->workers_data [i].total_time = 0;
 482                 context->workers_data [i].last_start = 0;
 483         }
 484         mono_memory_write_barrier ();
 485
 486         /*
 487          * We expect workers to start finishing only after all of them were awaken.
 488          * Otherwise we might think that we have fewer workers and use wrong context.
 489          */
 490         mono_os_mutex_lock (&context->finished_lock);
 491         sgen_workers_ensure_awake (context);
 492         mono_os_mutex_unlock (&context->finished_lock);
 493 }
 494
 495 void
 496 sgen_workers_join (int generation)
 497 {
 498         WorkerContext *context = &worker_contexts [generation];
 499         int i;
 500
 501         SGEN_ASSERT (0, !context->finish_callback, "Why are we joining concurrent mark early");
 502
 503         sgen_thread_pool_wait_for_all_jobs (context->thread_pool_context);
 504         sgen_thread_pool_idle_wait (context->thread_pool_context, continue_idle_wait);
 505         SGEN_ASSERT (0, !sgen_workers_are_working (context), "Can only signal enqueue work when in no work state");
 506
 507         /* At this point all the workers have stopped. */
 508
 509         SGEN_ASSERT (0, sgen_section_gray_queue_is_empty (&context->workers_distribute_gray_queue), "Why is there still work left to do?");
 510         for (i = 0; i < context->active_workers_num; ++i)
 511                 SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&context->workers_data [i].private_gray_queue), "Why is there still work left to do?");
 512
 513         context->started = FALSE;
 514 }
 515
 516 /*
 517  * Can only be called if the workers are not working in the
 518  * context and there are no pending jobs.
 519  */
 520 gboolean
 521 sgen_workers_have_idle_work (int generation)
 522 {
 523         WorkerContext *context = &worker_contexts [generation];
 524         int i;
 525
 526         if (!sgen_section_gray_queue_is_empty (&context->workers_distribute_gray_queue))
 527                 return TRUE;
 528
 529         for (i = 0; i < context->active_workers_num; ++i) {
 530                 if (!sgen_gray_object_queue_is_empty (&context->workers_data [i].private_gray_queue))
 531                         return TRUE;
 532         }
 533
 534         return FALSE;
 535 }
 536
 537 gboolean
 538 sgen_workers_all_done (void)
 539 {
 540         if (worker_contexts [GENERATION_NURSERY].workers_num && sgen_workers_are_working (&worker_contexts [GENERATION_NURSERY]))
 541                 return FALSE;
 542         if (worker_contexts [GENERATION_OLD].workers_num && sgen_workers_are_working (&worker_contexts [GENERATION_OLD]))
 543                 return FALSE;
 544
 545         return TRUE;
 546 }
 547
 548 void
 549 sgen_workers_assert_gray_queue_is_empty (int generation)
 550 {
 551         SGEN_ASSERT (0, sgen_section_gray_queue_is_empty (&worker_contexts [generation].workers_distribute_gray_queue), "Why is the workers gray queue not empty?");
 552 }
 553
 554 void
 555 sgen_workers_take_from_queue (int generation, SgenGrayQueue *queue)
 556 {
 557         WorkerContext *context = &worker_contexts [generation];
 558
 559         sgen_gray_object_spread (queue, sgen_workers_get_job_split_count (generation));
 560
 561         for (;;) {
 562                 GrayQueueSection *section = sgen_gray_object_dequeue_section (queue);
 563                 if (!section)
 564                         break;
 565                 sgen_section_gray_queue_enqueue (&context->workers_distribute_gray_queue, section);
 566         }
 567
 568         SGEN_ASSERT (0, !sgen_workers_are_working (context), "We should fully populate the distribute gray queue before we start the workers");
 569 }
 570
 571 SgenObjectOperations*
 572 sgen_workers_get_idle_func_object_ops (WorkerData *worker)
 573 {
 574         g_assert (worker->context->idle_func_object_ops);
 575         return worker->context->idle_func_object_ops;
 576 }
 577
 578 /*
 579  * If we have a single worker, splitting into multiple jobs makes no sense. With
 580  * more than one worker, we split into a larger number of jobs so that, in case
 581  * the work load is uneven, a worker that finished quickly can take up more jobs
 582  * than another one.
 583  *
 584  * We also return 1 if there is no worker context for that generation.
 585  */
 586 int
 587 sgen_workers_get_job_split_count (int generation)
 588 {
 589         return (worker_contexts [generation].active_workers_num > 1) ? worker_contexts [generation].active_workers_num * 4 : 1;
 590 }
 591
 592 void
 593 sgen_workers_foreach (int generation, SgenWorkerCallback callback)
 594 {
 595         WorkerContext *context = &worker_contexts [generation];
 596         int i;
 597
 598         for (i = 0; i < context->workers_num; i++)
 599                 callback (&context->workers_data [i]);
 600 }
 601
 602 gboolean
 603 sgen_workers_is_worker_thread (MonoNativeThreadId id)
 604 {
 605         return sgen_thread_pool_is_thread_pool_thread (id);
 606 }
 607
 608 #endif