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         binary_protocol_worker_finish (sgen_timestamp (), context->forced_stop);
 171
 172         sgen_gray_object_queue_trim_free_list (&data->private_gray_queue);
 173         return;
 174
 175 work_available:
 176         mono_os_mutex_unlock (&context->finished_lock);
 177 }
 178
 179 void
 180 sgen_workers_enqueue_job (int generation, SgenThreadPoolJob *job, gboolean enqueue)
 181 {
 182         if (!enqueue) {
 183                 job->func (NULL, job);
 184                 sgen_thread_pool_job_free (job);
 185                 return;
 186         }
 187
 188         sgen_thread_pool_job_enqueue (worker_contexts [generation].thread_pool_context, job);
 189 }
 190
 191 static gboolean
 192 workers_get_work (WorkerData *data)
 193 {
 194         SgenMajorCollector *major = sgen_get_major_collector ();
 195         SgenMinorCollector *minor = sgen_get_minor_collector ();
 196         GrayQueueSection *section;
 197
 198         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 199         g_assert (major->is_concurrent || minor->is_parallel);
 200
 201         section = sgen_section_gray_queue_dequeue (&data->context->workers_distribute_gray_queue);
 202         if (section) {
 203                 sgen_gray_object_enqueue_section (&data->private_gray_queue, section, major->is_parallel);
 204                 return TRUE;
 205         }
 206
 207         /* Nobody to steal from */
 208         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 209         return FALSE;
 210 }
 211
 212 static gboolean
 213 workers_steal_work (WorkerData *data)
 214 {
 215         SgenMajorCollector *major = sgen_get_major_collector ();
 216         SgenMinorCollector *minor = sgen_get_minor_collector ();
 217         int generation = sgen_get_current_collection_generation ();
 218         GrayQueueSection *section = NULL;
 219         WorkerContext *context = data->context;
 220         int i, current_worker;
 221
 222         if ((generation == GENERATION_OLD && !major->is_parallel) ||
 223                         (generation == GENERATION_NURSERY && !minor->is_parallel))
 224                 return FALSE;
 225
 226         /* If we're parallel, steal from other workers' private gray queues  */
 227         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 228
 229         current_worker = (int) (data - context->workers_data);
 230
 231         for (i = 1; i < context->active_workers_num && !section; i++) {
 232                 int steal_worker = (current_worker + i) % context->active_workers_num;
 233                 if (state_is_working_or_enqueued (context->workers_data [steal_worker].state))
 234                         section = sgen_gray_object_steal_section (&context->workers_data [steal_worker].private_gray_queue);
 235         }
 236
 237         if (section) {
 238                 sgen_gray_object_enqueue_section (&data->private_gray_queue, section, TRUE);
 239                 return TRUE;
 240         }
 241
 242         /* Nobody to steal from */
 243         g_assert (sgen_gray_object_queue_is_empty (&data->private_gray_queue));
 244         return FALSE;
 245 }
 246
 247 static void
 248 concurrent_enqueue_check (GCObject *obj)
 249 {
 250         g_assert (sgen_concurrent_collection_in_progress ());
 251         g_assert (!sgen_ptr_in_nursery (obj));
 252         g_assert (SGEN_LOAD_VTABLE (obj));
 253 }
 254
 255 static void
 256 init_private_gray_queue (WorkerData *data)
 257 {
 258         sgen_gray_object_queue_init (&data->private_gray_queue,
 259                         sgen_get_major_collector ()->is_concurrent ? concurrent_enqueue_check : NULL,
 260                         FALSE);
 261 }
 262
 263 static void
 264 thread_pool_init_func (void *data_untyped)
 265 {
 266         WorkerData *data = (WorkerData *)data_untyped;
 267         SgenMajorCollector *major = sgen_get_major_collector ();
 268         SgenMinorCollector *minor = sgen_get_minor_collector ();
 269
 270         if (!major->is_concurrent && !minor->is_parallel)
 271                 return;
 272
 273         init_private_gray_queue (data);
 274
 275         /* Separate WorkerData for same thread share free_block_lists */
 276         if (major->is_parallel || minor->is_parallel)
 277                 major->init_block_free_lists (&data->free_block_lists);
 278 }
 279
 280 static gboolean
 281 sgen_workers_are_working (WorkerContext *context)
 282 {
 283         int i;
 284
 285         for (i = 0; i < context->active_workers_num; i++) {
 286                 if (state_is_working_or_enqueued (context->workers_data [i].state))
 287                         return TRUE;
 288         }
 289         return FALSE;
 290 }
 291
 292 static gboolean
 293 continue_idle_func (void *data_untyped, int thread_pool_context)
 294 {
 295         if (data_untyped)
 296                 return state_is_working_or_enqueued (((WorkerData*)data_untyped)->state);
 297
 298         /* Return if any of the threads is working in the context */
 299         if (worker_contexts [GENERATION_NURSERY].workers_num && worker_contexts [GENERATION_NURSERY].thread_pool_context == thread_pool_context)
 300                 return sgen_workers_are_working (&worker_contexts [GENERATION_NURSERY]);
 301         if (worker_contexts [GENERATION_OLD].workers_num && worker_contexts [GENERATION_OLD].thread_pool_context == thread_pool_context)
 302                 return sgen_workers_are_working (&worker_contexts [GENERATION_OLD]);
 303
 304         g_assert_not_reached ();
 305         return FALSE;
 306 }
 307
 308 static gboolean
 309 should_work_func (void *data_untyped)
 310 {
 311         WorkerData *data = (WorkerData*)data_untyped;
 312         WorkerContext *context = data->context;
 313         int current_worker = (int) (data - context->workers_data);
 314
 315         return context->started && current_worker < context->active_workers_num && state_is_working_or_enqueued (data->state);
 316 }
 317
 318 static void
 319 marker_idle_func (void *data_untyped)
 320 {
 321         WorkerData *data = (WorkerData *)data_untyped;
 322         WorkerContext *context = data->context;
 323
 324         SGEN_ASSERT (0, continue_idle_func (data_untyped, context->thread_pool_context), "Why are we called when we're not supposed to work?");
 325
 326         if (data->state == STATE_WORK_ENQUEUED) {
 327                 set_state (data, STATE_WORK_ENQUEUED, STATE_WORKING);
 328                 SGEN_ASSERT (0, data->state != STATE_NOT_WORKING, "How did we get from WORK ENQUEUED to NOT WORKING?");
 329         }
 330
 331         if (!context->forced_stop && (!sgen_gray_object_queue_is_empty (&data->private_gray_queue) || workers_get_work (data) || workers_steal_work (data))) {
 332                 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (context->idle_func_object_ops, &data->private_gray_queue);
 333
 334                 SGEN_ASSERT (0, !sgen_gray_object_queue_is_empty (&data->private_gray_queue), "How is our gray queue empty if we just got work?");
 335
 336                 sgen_drain_gray_stack (ctx);
 337
 338                 if (data->private_gray_queue.num_sections >= SGEN_WORKER_MIN_SECTIONS_SIGNAL
 339                                 && context->workers_finished && context->worker_awakenings < context->active_workers_num) {
 340                         /* We bound the number of worker awakenings just to be sure */
 341                         context->worker_awakenings++;
 342                         mono_os_mutex_lock (&context->finished_lock);
 343                         sgen_workers_ensure_awake (context);
 344                         mono_os_mutex_unlock (&context->finished_lock);
 345                 }
 346         } else {
 347                 worker_try_finish (data);
 348         }
 349 }
 350
 351 static void
 352 init_distribute_gray_queue (WorkerContext *context)
 353 {
 354         sgen_section_gray_queue_init (&context->workers_distribute_gray_queue, TRUE,
 355                         sgen_get_major_collector ()->is_concurrent ? concurrent_enqueue_check : NULL);
 356 }
 357
 358 void
 359 sgen_workers_create_context (int generation, int num_workers)
 360 {
 361         static gboolean stat_inited = FALSE;
 362         int i;
 363         WorkerData **workers_data_ptrs = (WorkerData**)sgen_alloc_internal_dynamic (num_workers * sizeof(WorkerData*), INTERNAL_MEM_WORKER_DATA, TRUE);
 364         WorkerContext *context = &worker_contexts [generation];
 365
 366         SGEN_ASSERT (0, !context->workers_num, "We can't init the worker context for a generation twice");
 367
 368         mono_os_mutex_init (&context->finished_lock);
 369
 370         context->generation = generation;
 371         context->workers_num = num_workers;
 372         context->active_workers_num = num_workers;
 373
 374         context->workers_data = (WorkerData *)sgen_alloc_internal_dynamic (sizeof (WorkerData) * num_workers, INTERNAL_MEM_WORKER_DATA, TRUE);
 375         memset (context->workers_data, 0, sizeof (WorkerData) * num_workers);
 376
 377         init_distribute_gray_queue (context);
 378
 379         for (i = 0; i < num_workers; ++i) {
 380                 workers_data_ptrs [i] = &context->workers_data [i];
 381                 context->workers_data [i].context = context;
 382         }
 383
 384         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);
 385
 386         if (!stat_inited) {
 387                 mono_counters_register ("# workers finished", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_workers_num_finished);
 388                 stat_inited = TRUE;
 389         }
 390 }
 391
 392 /* This is called with thread pool lock so no context switch can happen */
 393 static gboolean
 394 continue_idle_wait (int calling_context, int *threads_context)
 395 {
 396         WorkerContext *context;
 397         int i;
 398
 399         if (worker_contexts [GENERATION_OLD].workers_num && calling_context == worker_contexts [GENERATION_OLD].thread_pool_context)
 400                 context = &worker_contexts [GENERATION_OLD];
 401         else if (worker_contexts [GENERATION_NURSERY].workers_num && calling_context == worker_contexts [GENERATION_NURSERY].thread_pool_context)
 402                 context = &worker_contexts [GENERATION_NURSERY];
 403         else
 404                 g_assert_not_reached ();
 405
 406         /*
 407          * We assume there are no pending jobs, since this is called only after
 408          * we waited for all the jobs.
 409          */
 410         for (i = 0; i < context->active_workers_num; i++) {
 411                 if (threads_context [i] == calling_context)
 412                         return TRUE;
 413         }
 414
 415         if (sgen_workers_have_idle_work (context->generation) && !context->forced_stop)
 416                 return TRUE;
 417
 418         /*
 419          * At this point there are no jobs to be done, and no objects to be scanned
 420          * in the gray queues. We can simply asynchronously finish all the workers
 421          * from the context that were not finished already (due to being stuck working
 422          * in another context)
 423          */
 424
 425         for (i = 0; i < context->active_workers_num; i++) {
 426                 if (context->workers_data [i].state == STATE_WORK_ENQUEUED)
 427                         set_state (&context->workers_data [i], STATE_WORK_ENQUEUED, STATE_WORKING);
 428                 if (context->workers_data [i].state == STATE_WORKING)
 429                         worker_try_finish (&context->workers_data [i]);
 430         }
 431
 432         return FALSE;
 433 }
 434
 435
 436 void
 437 sgen_workers_stop_all_workers (int generation)
 438 {
 439         WorkerContext *context = &worker_contexts [generation];
 440
 441         mono_os_mutex_lock (&context->finished_lock);
 442         context->finish_callback = NULL;
 443         mono_os_mutex_unlock (&context->finished_lock);
 444
 445         context->forced_stop = TRUE;
 446
 447         sgen_thread_pool_wait_for_all_jobs (context->thread_pool_context);
 448         sgen_thread_pool_idle_wait (context->thread_pool_context, continue_idle_wait);
 449         SGEN_ASSERT (0, !sgen_workers_are_working (context), "Can only signal enqueue work when in no work state");
 450
 451         context->started = FALSE;
 452 }
 453
 454 void
 455 sgen_workers_set_num_active_workers (int generation, int num_workers)
 456 {
 457         WorkerContext *context = &worker_contexts [generation];
 458         if (num_workers) {
 459                 SGEN_ASSERT (0, num_workers <= context->workers_num, "We can't start more workers than we initialized");
 460                 context->active_workers_num = num_workers;
 461         } else {
 462                 context->active_workers_num = context->workers_num;
 463         }
 464 }
 465
 466 void
 467 sgen_workers_start_all_workers (int generation, SgenObjectOperations *object_ops_nopar, SgenObjectOperations *object_ops_par, SgenWorkersFinishCallback callback)
 468 {
 469         WorkerContext *context = &worker_contexts [generation];
 470         int i;
 471         SGEN_ASSERT (0, !context->started, "Why are we starting to work without finishing previous cycle");
 472
 473         context->idle_func_object_ops_par = object_ops_par;
 474         context->idle_func_object_ops_nopar = object_ops_nopar;
 475         context->forced_stop = FALSE;
 476         context->finish_callback = callback;
 477         context->worker_awakenings = 0;
 478         context->started = TRUE;
 479
 480         for (i = 0; i < context->active_workers_num; i++) {
 481                 context->workers_data [i].major_scan_time = 0;
 482                 context->workers_data [i].los_scan_time = 0;
 483                 context->workers_data [i].total_time = 0;
 484                 context->workers_data [i].last_start = 0;
 485         }
 486         mono_memory_write_barrier ();
 487
 488         /*
 489          * We expect workers to start finishing only after all of them were awaken.
 490          * Otherwise we might think that we have fewer workers and use wrong context.
 491          */
 492         mono_os_mutex_lock (&context->finished_lock);
 493         sgen_workers_ensure_awake (context);
 494         mono_os_mutex_unlock (&context->finished_lock);
 495 }
 496
 497 void
 498 sgen_workers_join (int generation)
 499 {
 500         WorkerContext *context = &worker_contexts [generation];
 501         int i;
 502
 503         SGEN_ASSERT (0, !context->finish_callback, "Why are we joining concurrent mark early");
 504
 505         sgen_thread_pool_wait_for_all_jobs (context->thread_pool_context);
 506         sgen_thread_pool_idle_wait (context->thread_pool_context, continue_idle_wait);
 507         SGEN_ASSERT (0, !sgen_workers_are_working (context), "Can only signal enqueue work when in no work state");
 508
 509         /* At this point all the workers have stopped. */
 510
 511         SGEN_ASSERT (0, sgen_section_gray_queue_is_empty (&context->workers_distribute_gray_queue), "Why is there still work left to do?");
 512         for (i = 0; i < context->active_workers_num; ++i)
 513                 SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&context->workers_data [i].private_gray_queue), "Why is there still work left to do?");
 514
 515         context->started = FALSE;
 516 }
 517
 518 /*
 519  * Can only be called if the workers are not working in the
 520  * context and there are no pending jobs.
 521  */
 522 gboolean
 523 sgen_workers_have_idle_work (int generation)
 524 {
 525         WorkerContext *context = &worker_contexts [generation];
 526         int i;
 527
 528         if (!sgen_section_gray_queue_is_empty (&context->workers_distribute_gray_queue))
 529                 return TRUE;
 530
 531         for (i = 0; i < context->active_workers_num; ++i) {
 532                 if (!sgen_gray_object_queue_is_empty (&context->workers_data [i].private_gray_queue))
 533                         return TRUE;
 534         }
 535
 536         return FALSE;
 537 }
 538
 539 gboolean
 540 sgen_workers_all_done (void)
 541 {
 542         if (worker_contexts [GENERATION_NURSERY].workers_num && sgen_workers_are_working (&worker_contexts [GENERATION_NURSERY]))
 543                 return FALSE;
 544         if (worker_contexts [GENERATION_OLD].workers_num && sgen_workers_are_working (&worker_contexts [GENERATION_OLD]))
 545                 return FALSE;
 546
 547         return TRUE;
 548 }
 549
 550 void
 551 sgen_workers_assert_gray_queue_is_empty (int generation)
 552 {
 553         SGEN_ASSERT (0, sgen_section_gray_queue_is_empty (&worker_contexts [generation].workers_distribute_gray_queue), "Why is the workers gray queue not empty?");
 554 }
 555
 556 void
 557 sgen_workers_take_from_queue (int generation, SgenGrayQueue *queue)
 558 {
 559         WorkerContext *context = &worker_contexts [generation];
 560
 561         sgen_gray_object_spread (queue, sgen_workers_get_job_split_count (generation));
 562
 563         for (;;) {
 564                 GrayQueueSection *section = sgen_gray_object_dequeue_section (queue);
 565                 if (!section)
 566                         break;
 567                 sgen_section_gray_queue_enqueue (&context->workers_distribute_gray_queue, section);
 568         }
 569
 570         SGEN_ASSERT (0, !sgen_workers_are_working (context), "We should fully populate the distribute gray queue before we start the workers");
 571 }
 572
 573 SgenObjectOperations*
 574 sgen_workers_get_idle_func_object_ops (WorkerData *worker)
 575 {
 576         g_assert (worker->context->idle_func_object_ops);
 577         return worker->context->idle_func_object_ops;
 578 }
 579
 580 /*
 581  * If we have a single worker, splitting into multiple jobs makes no sense. With
 582  * more than one worker, we split into a larger number of jobs so that, in case
 583  * the work load is uneven, a worker that finished quickly can take up more jobs
 584  * than another one.
 585  *
 586  * We also return 1 if there is no worker context for that generation.
 587  */
 588 int
 589 sgen_workers_get_job_split_count (int generation)
 590 {
 591         return (worker_contexts [generation].active_workers_num > 1) ? worker_contexts [generation].active_workers_num * 4 : 1;
 592 }
 593
 594 void
 595 sgen_workers_foreach (int generation, SgenWorkerCallback callback)
 596 {
 597         WorkerContext *context = &worker_contexts [generation];
 598         int i;
 599
 600         for (i = 0; i < context->workers_num; i++)
 601                 callback (&context->workers_data [i]);
 602 }
 603
 604 gboolean
 605 sgen_workers_is_worker_thread (MonoNativeThreadId id)
 606 {
 607         return sgen_thread_pool_is_thread_pool_thread (id);
 608 }
 609
 610 #endif