[wasm] Implement GC support. Embedder must provide main loop pumping function request...
[mono.git] / mono / sgen / sgen-gc.c
index 3d04584377b8597dfc32aa46fb6f49483c1ab4b7..4c3454823fdd42c2f5e0073a87f650601d6b84bf 100644 (file)
 #include <errno.h>
 #include <assert.h>
 #include <stdlib.h>
+#include <glib.h>
 
 #include "mono/sgen/sgen-gc.h"
 #include "mono/sgen/sgen-cardtable.h"
 
 #include <mono/utils/memcheck.h>
 #include <mono/utils/mono-mmap-internals.h>
+#include <mono/utils/unlocked.h>
 
 #undef pthread_create
 #undef pthread_join
@@ -282,7 +284,8 @@ static guint64 time_major_pre_collection_fragment_clear = 0;
 static guint64 time_major_pinning = 0;
 static guint64 time_major_scan_pinned = 0;
 static guint64 time_major_scan_roots = 0;
-static guint64 time_major_scan_mod_union = 0;
+static guint64 time_major_scan_mod_union_blocks = 0;
+static guint64 time_major_scan_mod_union_los = 0;
 static guint64 time_major_finish_gray_stack = 0;
 static guint64 time_major_free_bigobjs = 0;
 static guint64 time_major_los_sweep = 0;
@@ -334,13 +337,6 @@ nursery_canaries_enabled (void)
 
 #define safe_object_get_size   sgen_safe_object_get_size
 
-#if defined(HAVE_CONC_GC_AS_DEFAULT)
-/* Use concurrent major on deskstop platforms */
-#define DEFAULT_MAJOR SGEN_MAJOR_CONCURRENT
-#else
-#define DEFAULT_MAJOR SGEN_MAJOR_SERIAL
-#endif
-
 typedef enum {
        SGEN_MAJOR_DEFAULT,
        SGEN_MAJOR_SERIAL,
@@ -454,7 +450,7 @@ sgen_workers_get_job_gray_queue (WorkerData *worker_data, SgenGrayQueue *default
 static void
 gray_queue_redirect (SgenGrayQueue *queue)
 {
-       sgen_workers_take_from_queue (queue);
+       sgen_workers_take_from_queue (current_collection_generation, queue);
 }
 
 void
@@ -1279,7 +1275,8 @@ init_stats (void)
        mono_counters_register ("Major pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pinning);
        mono_counters_register ("Major scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_pinned);
        mono_counters_register ("Major scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_roots);
-       mono_counters_register ("Major scan mod union", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union);
+       mono_counters_register ("Major scan mod union blocks", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union_blocks);
+       mono_counters_register ("Major scan mod union los", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union_los);
        mono_counters_register ("Major finish gray stack", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_finish_gray_stack);
        mono_counters_register ("Major free big objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_free_bigobjs);
        mono_counters_register ("Major LOS sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_los_sweep);
@@ -1361,6 +1358,7 @@ typedef struct {
 typedef struct {
        ScanJob scan_job;
        int job_index, job_split_count;
+       int data;
 } ParallelScanJob;
 
 static ScanCopyContext
@@ -1375,7 +1373,7 @@ scan_copy_context_for_scan_job (void *worker_data_untyped, ScanJob *job)
                 * object ops changes, like forced concurrent finish.
                 */
                SGEN_ASSERT (0, sgen_workers_is_worker_thread (mono_native_thread_id_get ()), "We need a context for the scan job");
-               job->ops = sgen_workers_get_idle_func_object_ops ();
+               job->ops = sgen_workers_get_idle_func_object_ops (worker_data);
        }
 
        return CONTEXT_FROM_OBJECT_OPERATIONS (job->ops, sgen_workers_get_job_gray_queue (worker_data, job->gc_thread_gray_queue));
@@ -1444,9 +1442,12 @@ job_scan_major_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
        ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, (ScanJob*)job_data);
 
        SGEN_TV_GETTIME (atv);
-       major_collector.scan_card_table (CARDTABLE_SCAN_GLOBAL, ctx, job_data->job_index, job_data->job_split_count);
+       major_collector.scan_card_table (CARDTABLE_SCAN_GLOBAL, ctx, job_data->job_index, job_data->job_split_count, job_data->data);
        SGEN_TV_GETTIME (btv);
        time_minor_scan_major_blocks += SGEN_TV_ELAPSED (atv, btv);
+
+       if (worker_data_untyped)
+               ((WorkerData*)worker_data_untyped)->major_scan_time += SGEN_TV_ELAPSED (atv, btv);
 }
 
 static void
@@ -1461,48 +1462,79 @@ job_scan_los_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
        sgen_los_scan_card_table (CARDTABLE_SCAN_GLOBAL, ctx, job_data->job_index, job_data->job_split_count);
        SGEN_TV_GETTIME (btv);
        time_minor_scan_los += SGEN_TV_ELAPSED (atv, btv);
+
+       if (worker_data_untyped)
+               ((WorkerData*)worker_data_untyped)->los_scan_time += SGEN_TV_ELAPSED (atv, btv);
 }
 
 static void
 job_scan_major_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
 {
+       SGEN_TV_DECLARE (atv);
+       SGEN_TV_DECLARE (btv);
        ParallelScanJob *job_data = (ParallelScanJob*)job;
        ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, (ScanJob*)job_data);
 
        g_assert (concurrent_collection_in_progress);
-       major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx, job_data->job_index, job_data->job_split_count);
+       SGEN_TV_GETTIME (atv);
+       major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx, job_data->job_index, job_data->job_split_count, job_data->data);
+       SGEN_TV_GETTIME (btv);
+       time_major_scan_mod_union_blocks += SGEN_TV_ELAPSED (atv, btv);
+
+       if (worker_data_untyped)
+               ((WorkerData*)worker_data_untyped)->major_scan_time += SGEN_TV_ELAPSED (atv, btv);
 }
 
 static void
 job_scan_los_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
 {
+       SGEN_TV_DECLARE (atv);
+       SGEN_TV_DECLARE (btv);
        ParallelScanJob *job_data = (ParallelScanJob*)job;
        ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, (ScanJob*)job_data);
 
        g_assert (concurrent_collection_in_progress);
+       SGEN_TV_GETTIME (atv);
        sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx, job_data->job_index, job_data->job_split_count);
+       SGEN_TV_GETTIME (btv);
+       time_major_scan_mod_union_los += SGEN_TV_ELAPSED (atv, btv);
+
+       if (worker_data_untyped)
+               ((WorkerData*)worker_data_untyped)->los_scan_time += SGEN_TV_ELAPSED (atv, btv);
 }
 
 static void
 job_major_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
 {
+       SGEN_TV_DECLARE (atv);
+       SGEN_TV_DECLARE (btv);
        ParallelScanJob *job_data = (ParallelScanJob*)job;
        ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, (ScanJob*)job_data);
 
        g_assert (concurrent_collection_in_progress);
+       SGEN_TV_GETTIME (atv);
+       major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx, job_data->job_index, job_data->job_split_count, job_data->data);
+       SGEN_TV_GETTIME (btv);
 
-       major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx, job_data->job_index, job_data->job_split_count);
+       g_assert (worker_data_untyped);
+       ((WorkerData*)worker_data_untyped)->major_scan_time += SGEN_TV_ELAPSED (atv, btv);
 }
 
 static void
 job_los_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
 {
+       SGEN_TV_DECLARE (atv);
+       SGEN_TV_DECLARE (btv);
        ParallelScanJob *job_data = (ParallelScanJob*)job;
        ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, (ScanJob*)job_data);
 
        g_assert (concurrent_collection_in_progress);
-
+       SGEN_TV_GETTIME (atv);
        sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx, job_data->job_index, job_data->job_split_count);
+       SGEN_TV_GETTIME (btv);
+
+       g_assert (worker_data_untyped);
+       ((WorkerData*)worker_data_untyped)->los_scan_time += SGEN_TV_ELAPSED (atv, btv);
 }
 
 static void
@@ -1521,7 +1553,8 @@ workers_finish_callback (void)
 {
        ParallelScanJob *psj;
        ScanJob *sj;
-       int split_count = sgen_workers_get_job_split_count ();
+       size_t num_major_sections = major_collector.get_num_major_sections ();
+       int split_count = sgen_workers_get_job_split_count (GENERATION_OLD);
        int i;
        /* Mod union preclean jobs */
        for (i = 0; i < split_count; i++) {
@@ -1529,7 +1562,8 @@ workers_finish_callback (void)
                psj->scan_job.gc_thread_gray_queue = NULL;
                psj->job_index = i;
                psj->job_split_count = split_count;
-               sgen_workers_enqueue_job (&psj->scan_job.job, TRUE);
+               psj->data = num_major_sections / split_count;
+               sgen_workers_enqueue_job (GENERATION_OLD, &psj->scan_job.job, TRUE);
        }
 
        for (i = 0; i < split_count; i++) {
@@ -1537,12 +1571,12 @@ workers_finish_callback (void)
                psj->scan_job.gc_thread_gray_queue = NULL;
                psj->job_index = i;
                psj->job_split_count = split_count;
-               sgen_workers_enqueue_job (&psj->scan_job.job, TRUE);
+               sgen_workers_enqueue_job (GENERATION_OLD, &psj->scan_job.job, TRUE);
        }
 
        sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan last pinned", job_scan_last_pinned, sizeof (ScanJob));
        sj->gc_thread_gray_queue = NULL;
-       sgen_workers_enqueue_job (&sj->job, TRUE);
+       sgen_workers_enqueue_job (GENERATION_OLD, &sj->job, TRUE);
 }
 
 static void
@@ -1554,13 +1588,14 @@ init_gray_queue (SgenGrayQueue *gc_thread_gray_queue)
 static void
 enqueue_scan_remembered_set_jobs (SgenGrayQueue *gc_thread_gray_queue, SgenObjectOperations *ops, gboolean enqueue)
 {
-       int i, split_count = sgen_workers_get_job_split_count ();
+       int i, split_count = sgen_workers_get_job_split_count (GENERATION_NURSERY);
+       size_t num_major_sections = major_collector.get_num_major_sections ();
        ScanJob *sj;
 
        sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan wbroots", job_scan_wbroots, sizeof (ScanJob));
        sj->ops = ops;
        sj->gc_thread_gray_queue = gc_thread_gray_queue;
-       sgen_workers_enqueue_job (&sj->job, enqueue);
+       sgen_workers_enqueue_job (GENERATION_NURSERY, &sj->job, enqueue);
 
        for (i = 0; i < split_count; i++) {
                ParallelScanJob *psj;
@@ -1570,14 +1605,15 @@ enqueue_scan_remembered_set_jobs (SgenGrayQueue *gc_thread_gray_queue, SgenObjec
                psj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
                psj->job_index = i;
                psj->job_split_count = split_count;
-               sgen_workers_enqueue_job (&psj->scan_job.job, enqueue);
+               psj->data = num_major_sections / split_count;
+               sgen_workers_enqueue_job (GENERATION_NURSERY, &psj->scan_job.job, enqueue);
 
                psj = (ParallelScanJob*)sgen_thread_pool_job_alloc ("scan LOS remsets", job_scan_los_card_table, sizeof (ParallelScanJob));
                psj->scan_job.ops = ops;
                psj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
                psj->job_index = i;
                psj->job_split_count = split_count;
-               sgen_workers_enqueue_job (&psj->scan_job.job, enqueue);
+               sgen_workers_enqueue_job (GENERATION_NURSERY, &psj->scan_job.job, enqueue);
        }
 }
 
@@ -1596,7 +1632,7 @@ enqueue_scan_from_roots_jobs (SgenGrayQueue *gc_thread_gray_queue, char *heap_st
        scrrj->heap_start = heap_start;
        scrrj->heap_end = heap_end;
        scrrj->root_type = ROOT_TYPE_NORMAL;
-       sgen_workers_enqueue_job (&scrrj->scan_job.job, enqueue);
+       sgen_workers_enqueue_job (current_collection_generation, &scrrj->scan_job.job, enqueue);
 
        if (current_collection_generation == GENERATION_OLD) {
                /* During minors we scan the cardtable for these roots instead */
@@ -1606,7 +1642,7 @@ enqueue_scan_from_roots_jobs (SgenGrayQueue *gc_thread_gray_queue, char *heap_st
                scrrj->heap_start = heap_start;
                scrrj->heap_end = heap_end;
                scrrj->root_type = ROOT_TYPE_WBARRIER;
-               sgen_workers_enqueue_job (&scrrj->scan_job.job, enqueue);
+               sgen_workers_enqueue_job (current_collection_generation, &scrrj->scan_job.job, enqueue);
        }
 
        /* Threads */
@@ -1616,7 +1652,7 @@ enqueue_scan_from_roots_jobs (SgenGrayQueue *gc_thread_gray_queue, char *heap_st
        stdj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
        stdj->heap_start = heap_start;
        stdj->heap_end = heap_end;
-       sgen_workers_enqueue_job (&stdj->scan_job.job, enqueue);
+       sgen_workers_enqueue_job (current_collection_generation, &stdj->scan_job.job, enqueue);
 
        /* Scan the list of objects ready for finalization. */
 
@@ -1624,13 +1660,13 @@ enqueue_scan_from_roots_jobs (SgenGrayQueue *gc_thread_gray_queue, char *heap_st
        sfej->scan_job.ops = ops;
        sfej->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
        sfej->queue = &fin_ready_queue;
-       sgen_workers_enqueue_job (&sfej->scan_job.job, enqueue);
+       sgen_workers_enqueue_job (current_collection_generation, &sfej->scan_job.job, enqueue);
 
        sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan critical finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
        sfej->scan_job.ops = ops;
        sfej->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
        sfej->queue = &critical_fin_queue;
-       sgen_workers_enqueue_job (&sfej->scan_job.job, enqueue);
+       sgen_workers_enqueue_job (current_collection_generation, &sfej->scan_job.job, enqueue);
 }
 
 /*
@@ -1650,6 +1686,9 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
        TV_DECLARE (btv);
        SGEN_TV_DECLARE (last_minor_collection_start_tv);
        SGEN_TV_DECLARE (last_minor_collection_end_tv);
+       guint64 major_scan_start = time_minor_scan_major_blocks;
+       guint64 los_scan_start = time_minor_scan_los;
+       guint64 finish_gray_start = time_minor_finish_gray_stack;
 
        if (disable_minor_collections)
                return TRUE;
@@ -1657,17 +1696,16 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
        TV_GETTIME (last_minor_collection_start_tv);
        atv = last_minor_collection_start_tv;
 
-       binary_protocol_collection_begin (gc_stats.minor_gc_count, GENERATION_NURSERY);
+       binary_protocol_collection_begin (InterlockedRead (&gc_stats.minor_gc_count), GENERATION_NURSERY);
 
-       if (sgen_concurrent_collection_in_progress ()) {
-               /* FIXME Support parallel nursery collections with concurrent major */
-               object_ops_nopar = &sgen_minor_collector.serial_ops_with_concurrent_major;
-       } else {
-               object_ops_nopar = &sgen_minor_collector.serial_ops;
-               if (sgen_minor_collector.is_parallel && sgen_nursery_size >= SGEN_PARALLEL_MINOR_MIN_NURSERY_SIZE) {
-                       object_ops_par = &sgen_minor_collector.parallel_ops;
-                       is_parallel = TRUE;
-               }
+       object_ops_nopar = sgen_concurrent_collection_in_progress ()
+                               ? &sgen_minor_collector.serial_ops_with_concurrent_major
+                               : &sgen_minor_collector.serial_ops;
+       if (sgen_minor_collector.is_parallel && sgen_nursery_size >= SGEN_PARALLEL_MINOR_MIN_NURSERY_SIZE) {
+               object_ops_par = sgen_concurrent_collection_in_progress ()
+                                       ? &sgen_minor_collector.parallel_ops_with_concurrent_major
+                                       : &sgen_minor_collector.parallel_ops;
+               is_parallel = TRUE;
        }
 
        if (do_verify_nursery || do_dump_nursery_content)
@@ -1686,7 +1724,7 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
        degraded_mode = 0;
        objects_pinned = 0;
 
-       SGEN_LOG (1, "Start nursery collection %d %p-%p, size: %d", gc_stats.minor_gc_count, nursery_section->data, nursery_section->end_data, (int)(nursery_section->end_data - nursery_section->data));
+       SGEN_LOG (1, "Start nursery collection %" G_GINT32_FORMAT " %p-%p, size: %d", InterlockedRead (&gc_stats.minor_gc_count), nursery_section->data, nursery_section->end_data, (int)(nursery_section->end_data - nursery_section->data));
 
        /* world must be stopped already */
        TV_GETTIME (btv);
@@ -1701,7 +1739,7 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
        init_gray_queue (&gc_thread_gray_queue);
        ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops_nopar, &gc_thread_gray_queue);
 
-       gc_stats.minor_gc_count ++;
+       InterlockedIncrement (&gc_stats.minor_gc_count);
 
        sgen_process_fin_stage_entries ();
 
@@ -1756,8 +1794,8 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
 
        if (is_parallel) {
                gray_queue_redirect (&gc_thread_gray_queue);
-               sgen_workers_start_all_workers (object_ops_nopar, object_ops_par, NULL);
-               sgen_workers_join ();
+               sgen_workers_start_all_workers (GENERATION_NURSERY, object_ops_nopar, object_ops_par, NULL);
+               sgen_workers_join (GENERATION_NURSERY);
        }
 
        TV_GETTIME (btv);
@@ -1818,9 +1856,9 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
        major_collector.finish_nursery_collection ();
 
        TV_GETTIME (last_minor_collection_end_tv);
-       gc_stats.minor_gc_time += TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
+       UnlockedAdd64 (&gc_stats.minor_gc_time, TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv));
 
-       sgen_debug_dump_heap ("minor", gc_stats.minor_gc_count - 1, NULL);
+       sgen_debug_dump_heap ("minor", InterlockedRead (&gc_stats.minor_gc_count) - 1, NULL);
 
        /* prepare the pin queue for the next collection */
        sgen_finish_pinning ();
@@ -1845,7 +1883,15 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
        current_collection_generation = -1;
        objects_pinned = 0;
 
-       binary_protocol_collection_end (gc_stats.minor_gc_count - 1, GENERATION_NURSERY, 0, 0);
+       if (is_parallel)
+               binary_protocol_collection_end_stats (0, 0, time_minor_finish_gray_stack - finish_gray_start);
+       else
+               binary_protocol_collection_end_stats (
+                       time_minor_scan_major_blocks - major_scan_start,
+                       time_minor_scan_los - los_scan_start,
+                       time_minor_finish_gray_stack - finish_gray_start);
+
+       binary_protocol_collection_end (InterlockedRead (&gc_stats.minor_gc_count) - 1, GENERATION_NURSERY, 0, 0);
 
        if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
                sgen_check_nursery_objects_pinned (unpin_queue != NULL);
@@ -1990,15 +2036,18 @@ major_copy_or_mark_from_roots (SgenGrayQueue *gc_thread_gray_queue, size_t *old_
        SGEN_ASSERT (0, sgen_workers_all_done (), "Why are the workers not done when we start or finish a major collection?");
        if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
                if (object_ops_par != NULL)
-                       sgen_workers_set_num_active_workers (0);
-               if (sgen_workers_have_idle_work ()) {
+                       sgen_workers_set_num_active_workers (GENERATION_OLD, 0);
+               if (object_ops_par == NULL && sgen_workers_have_idle_work (GENERATION_OLD)) {
                        /*
                         * We force the finish of the worker with the new object ops context
-                        * which can also do copying. We need to have finished pinning.
+                        * which can also do copying. We need to have finished pinning. On the
+                        * parallel collector, there is no need to drain the private queues
+                        * here, since we can do it as part of the finishing work, achieving
+                        * better work distribution.
                         */
-                       sgen_workers_start_all_workers (object_ops_nopar, object_ops_par, NULL);
+                       sgen_workers_start_all_workers (GENERATION_OLD, object_ops_nopar, object_ops_par, NULL);
 
-                       sgen_workers_join ();
+                       sgen_workers_join (GENERATION_OLD);
                }
        }
 
@@ -2024,17 +2073,18 @@ major_copy_or_mark_from_roots (SgenGrayQueue *gc_thread_gray_queue, size_t *old_
         * the roots.
         */
        if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
-               sgen_workers_set_num_active_workers (1);
+               sgen_workers_set_num_active_workers (GENERATION_OLD, 1);
                gray_queue_redirect (gc_thread_gray_queue);
                if (precleaning_enabled) {
-                       sgen_workers_start_all_workers (object_ops_nopar, object_ops_par, workers_finish_callback);
+                       sgen_workers_start_all_workers (GENERATION_OLD, object_ops_nopar, object_ops_par, workers_finish_callback);
                } else {
-                       sgen_workers_start_all_workers (object_ops_nopar, object_ops_par, NULL);
+                       sgen_workers_start_all_workers (GENERATION_OLD, object_ops_nopar, object_ops_par, NULL);
                }
        }
 
        if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
-               int i, split_count = sgen_workers_get_job_split_count ();
+               int i, split_count = sgen_workers_get_job_split_count (GENERATION_OLD);
+               size_t num_major_sections = major_collector.get_num_major_sections ();
                gboolean parallel = object_ops_par != NULL;
 
                /* If we're not parallel we finish the collection on the gc thread */
@@ -2050,14 +2100,15 @@ major_copy_or_mark_from_roots (SgenGrayQueue *gc_thread_gray_queue, size_t *old_
                        psj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
                        psj->job_index = i;
                        psj->job_split_count = split_count;
-                       sgen_workers_enqueue_job (&psj->scan_job.job, parallel);
+                       psj->data = num_major_sections / split_count;
+                       sgen_workers_enqueue_job (GENERATION_OLD, &psj->scan_job.job, parallel);
 
                        psj = (ParallelScanJob*)sgen_thread_pool_job_alloc ("scan LOS mod union cardtable", job_scan_los_mod_union_card_table, sizeof (ParallelScanJob));
                        psj->scan_job.ops = parallel ? NULL : object_ops_nopar;
                        psj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
                        psj->job_index = i;
                        psj->job_split_count = split_count;
-                       sgen_workers_enqueue_job (&psj->scan_job.job, parallel);
+                       sgen_workers_enqueue_job (GENERATION_OLD, &psj->scan_job.job, parallel);
                }
 
                if (parallel) {
@@ -2069,8 +2120,8 @@ major_copy_or_mark_from_roots (SgenGrayQueue *gc_thread_gray_queue, size_t *old_
                         * stack that contained roots and pinned objects and also scan the mod union card
                         * table.
                         */
-                       sgen_workers_start_all_workers (object_ops_nopar, object_ops_par, NULL);
-                       sgen_workers_join ();
+                       sgen_workers_start_all_workers (GENERATION_OLD, object_ops_nopar, object_ops_par, NULL);
+                       sgen_workers_join (GENERATION_OLD);
                }
        }
 
@@ -2091,11 +2142,11 @@ major_start_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason,
 {
        SgenObjectOperations *object_ops_nopar, *object_ops_par = NULL;
 
-       binary_protocol_collection_begin (gc_stats.major_gc_count, GENERATION_OLD);
+       binary_protocol_collection_begin (InterlockedRead (&gc_stats.major_gc_count), GENERATION_OLD);
 
        current_collection_generation = GENERATION_OLD;
 
-       sgen_workers_assert_gray_queue_is_empty ();
+       sgen_workers_assert_gray_queue_is_empty (GENERATION_OLD);
 
        if (!concurrent)
                sgen_cement_reset ();
@@ -2122,8 +2173,8 @@ major_start_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason,
        check_scan_starts ();
 
        degraded_mode = 0;
-       SGEN_LOG (1, "Start major collection %d", gc_stats.major_gc_count);
-       gc_stats.major_gc_count ++;
+       SGEN_LOG (1, "Start major collection %" G_GINT32_FORMAT, InterlockedRead (&gc_stats.major_gc_count));
+       InterlockedIncrement (&gc_stats.major_gc_count);
 
        if (major_collector.start_major_collection)
                major_collector.start_major_collection ();
@@ -2139,8 +2190,9 @@ major_finish_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason
        mword fragment_total;
        TV_DECLARE (atv);
        TV_DECLARE (btv);
-
-       TV_GETTIME (btv);
+       guint64 major_scan_start = time_major_scan_mod_union_blocks;
+       guint64 los_scan_start = time_major_scan_mod_union_los;
+       guint64 finish_gray_start = time_major_finish_gray_stack;
 
        if (concurrent_collection_in_progress) {
                SgenObjectOperations *object_ops_par = NULL;
@@ -2158,8 +2210,9 @@ major_finish_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason
                object_ops_nopar = &major_collector.major_ops_serial;
        }
 
-       sgen_workers_assert_gray_queue_is_empty ();
+       sgen_workers_assert_gray_queue_is_empty (GENERATION_OLD);
 
+       TV_GETTIME (btv);
        finish_gray_stack (GENERATION_OLD, CONTEXT_FROM_OBJECT_OPERATIONS (object_ops_nopar, gc_thread_gray_queue));
        TV_GETTIME (atv);
        time_major_finish_gray_stack += TV_ELAPSED (btv, atv);
@@ -2237,7 +2290,7 @@ major_finish_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason
        TV_GETTIME (atv);
        time_major_sweep += TV_ELAPSED (btv, atv);
 
-       sgen_debug_dump_heap ("major", gc_stats.major_gc_count - 1, reason);
+       sgen_debug_dump_heap ("major", InterlockedRead (&gc_stats.major_gc_count) - 1, reason);
 
        if (sgen_have_pending_finalizers ()) {
                SGEN_LOG (4, "Finalizer-thread wakeup");
@@ -2250,7 +2303,7 @@ major_finish_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason
        memset (&counts, 0, sizeof (ScannedObjectCounts));
        major_collector.finish_major_collection (&counts);
 
-       sgen_workers_assert_gray_queue_is_empty ();
+       sgen_workers_assert_gray_queue_is_empty (GENERATION_OLD);
 
        SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after major collection has finished");
        if (concurrent_collection_in_progress)
@@ -2261,8 +2314,15 @@ major_finish_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason
        binary_protocol_flush_buffers (FALSE);
 
        //consistency_check ();
+       if (major_collector.is_parallel)
+                binary_protocol_collection_end_stats (0, 0, time_major_finish_gray_stack - finish_gray_start);
+        else
+                binary_protocol_collection_end_stats (
+                        time_major_scan_mod_union_blocks - major_scan_start,
+                        time_major_scan_mod_union_los - los_scan_start,
+                        time_major_finish_gray_stack - finish_gray_start);
 
-       binary_protocol_collection_end (gc_stats.major_gc_count - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
+       binary_protocol_collection_end (InterlockedRead (&gc_stats.major_gc_count) - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
 }
 
 static gboolean
@@ -2290,7 +2350,7 @@ major_do_collection (const char *reason, gboolean is_overflow, gboolean forced)
        sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
 
        TV_GETTIME (time_end);
-       gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
+       UnlockedAdd64 (&gc_stats.major_gc_time, TV_ELAPSED (time_start, time_end));
 
        /* FIXME: also report this to the user, preferably in gc-end. */
        if (major_collector.get_and_reset_num_major_objects_marked)
@@ -2326,7 +2386,7 @@ major_start_concurrent_collection (const char *reason)
        num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
 
        TV_GETTIME (time_end);
-       gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
+       UnlockedAdd64 (&gc_stats.major_gc_time, TV_ELAPSED (time_start, time_end));
 
        current_collection_generation = -1;
 }
@@ -2354,7 +2414,7 @@ major_update_concurrent_collection (void)
        sgen_los_update_cardtable_mod_union ();
 
        TV_GETTIME (total_end);
-       gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
+       UnlockedAdd64 (&gc_stats.major_gc_time, TV_ELAPSED (total_start, total_end));
 }
 
 static void
@@ -2373,10 +2433,10 @@ major_finish_concurrent_collection (gboolean forced)
         * The workers will be resumed with a finishing pause context to avoid
         * additional cardtable and object scanning.
         */
-       sgen_workers_stop_all_workers ();
+       sgen_workers_stop_all_workers (GENERATION_OLD);
 
        SGEN_TV_GETTIME (time_major_conc_collection_end);
-       gc_stats.major_gc_time_concurrent += SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end);
+       UnlockedAdd64 (&gc_stats.major_gc_time_concurrent, SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end));
 
        major_collector.update_cardtable_mod_union ();
        sgen_los_update_cardtable_mod_union ();
@@ -2391,7 +2451,7 @@ major_finish_concurrent_collection (gboolean forced)
        sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
 
        TV_GETTIME (total_end);
-       gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
+       UnlockedAdd64 (&gc_stats.major_gc_time, TV_ELAPSED (total_start, total_end));
 
        current_collection_generation = -1;
 }
@@ -2443,7 +2503,7 @@ sgen_ensure_free_space (size_t size, int generation)
  * LOCKING: Assumes the GC lock is held.
  */
 void
-sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish, gboolean stw)
+sgen_perform_collection_inner (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish, gboolean stw)
 {
        TV_DECLARE (gc_total_start);
        TV_DECLARE (gc_total_end);
@@ -2522,6 +2582,52 @@ sgen_perform_collection (size_t requested_size, int generation_to_collect, const
                sgen_restart_world (oldest_generation_collected);
 }
 
+#ifdef HOST_WASM
+
+typedef struct {
+       size_t requested_size;
+       int generation_to_collect;
+       const char *reason;
+} SgenGcRequest;
+
+static SgenGcRequest gc_request;
+static gboolean pending_request;
+
+extern void request_gc_cycle (void);
+
+#include <emscripten.h>
+
+EMSCRIPTEN_KEEPALIVE void
+mono_gc_pump_callback (void)
+{
+       if (!pending_request)
+               return;
+       pending_request = FALSE;
+       sgen_perform_collection_inner (gc_request.requested_size, gc_request.generation_to_collect, gc_request.reason, TRUE, TRUE);     
+}
+#endif
+
+void
+sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish, gboolean stw)
+{
+#ifdef HOST_WASM
+       g_assert (stw); //can't handle non-stw mode (IE, domain unload)
+       //we ignore wait_to_finish
+       if (!pending_request || gc_request.generation_to_collect <= generation_to_collect) { //no active request or request was for a smaller part of the heap
+               gc_request.requested_size = requested_size;
+               gc_request.generation_to_collect = generation_to_collect;
+               gc_request.reason = reason;
+               if (!pending_request) {
+                       request_gc_cycle ();
+                       pending_request = TRUE;
+               }
+       }
+
+       degraded_mode = 1; //enable degraded mode so allocation can continue
+#else
+       sgen_perform_collection_inner (requested_size, generation_to_collect, reason, wait_to_finish, stw);
+#endif
+}
 /*
  * ######################################################################
  * ########  Memory allocation from the OS
@@ -2988,9 +3094,7 @@ sgen_gc_collect (int generation)
 int
 sgen_gc_collection_count (int generation)
 {
-       if (generation == 0)
-               return gc_stats.minor_gc_count;
-       return gc_stats.major_gc_count;
+       return InterlockedRead (generation == GENERATION_NURSERY ? &gc_stats.minor_gc_count : &gc_stats.major_gc_count);
 }
 
 size_t
@@ -3172,9 +3276,8 @@ init_sgen_mode (SgenMode mode)
                /*
                 * Use concurrent major and dynamic nursery with a more
                 * aggressive shrinking relative to pause times.
-                * FIXME use parallel minors
                 */
-               minor = SGEN_MINOR_SIMPLE;
+               minor = SGEN_MINOR_SIMPLE_PARALLEL;
                major = SGEN_MAJOR_CONCURRENT;
                dynamic_nursery = TRUE;
                sgen_max_pause_margin = SGEN_PAUSE_MODE_MAX_PAUSE_MARGIN;
@@ -3607,19 +3710,7 @@ sgen_gc_init (void)
        if (major_collector.post_param_init)
                major_collector.post_param_init (&major_collector);
 
-       if (major_collector.is_concurrent || sgen_minor_collector.is_parallel) {
-               int num_workers = 1;
-               if (major_collector.is_parallel || sgen_minor_collector.is_parallel) {
-                       num_workers = mono_cpu_count ();
-                       if (num_workers <= 1) {
-                               num_workers = 1;
-                               major_collector.is_parallel = FALSE;
-                               sgen_minor_collector.is_parallel = FALSE;
-                       }
-               }
-               if (major_collector.is_concurrent || sgen_minor_collector.is_parallel)
-                       sgen_workers_init (num_workers, (SgenWorkerCallback) major_collector.worker_init_cb);
-       }
+       sgen_thread_pool_start ();
 
        sgen_memgov_init (max_heap, soft_limit, debug_print_allowance, allowance_ratio, save_target);