From: Vlad Brezae <brezaevlad@gmail.com>
Date: Tue, 31 May 2016 20:55:41 +0000 (+0300)
Subject: [sgen] Enqueue preclean through a worker finish callback
X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=commitdiff_plain;h=5f2d0db2babca3623a67a11d2b26198281a93b65;p=mono.git

[sgen] Enqueue preclean through a worker finish callback

It moves enqueuing back to the main gc giving more flexibility.
---

diff --git a/mono/sgen/sgen-gc.c b/mono/sgen/sgen-gc.c
index a58213f6c9a..0f98b228f88 100644
--- a/mono/sgen/sgen-gc.c
+++ b/mono/sgen/sgen-gc.c
@@ -1417,6 +1417,18 @@ job_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
 	sgen_scan_pin_queue_objects (ctx);
 }
 
+static void
+workers_finish_callback (void)
+{
+	ScanJob *sj;
+	/* Mod union preclean job */
+	sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_mod_union_preclean, sizeof (ScanJob));
+	sj->ops = sgen_workers_get_idle_func_object_ops ();
+	sj->gc_thread_gray_queue = NULL;
+
+	sgen_workers_enqueue_job (&sj->job, TRUE);
+}
+
 static void
 init_gray_queue (SgenGrayQueue *gc_thread_gray_queue, gboolean use_workers)
 {
@@ -1852,12 +1864,7 @@ major_copy_or_mark_from_roots (SgenGrayQueue *gc_thread_gray_queue, size_t *old_
 	 */
 	if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
 		if (precleaning_enabled) {
-			ScanJob *sj;
-			/* Mod union preclean job */
-			sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_mod_union_preclean, sizeof (ScanJob));
-			sj->ops = object_ops;
-			sj->gc_thread_gray_queue = NULL;
-			sgen_workers_start_all_workers (object_ops, &sj->job);
+			sgen_workers_start_all_workers (object_ops, workers_finish_callback);
 		} else {
 			sgen_workers_start_all_workers (object_ops, NULL);
 		}
diff --git a/mono/sgen/sgen-workers.c b/mono/sgen/sgen-workers.c
index f884d79a1d6..49f5ccf3548 100644
--- a/mono/sgen/sgen-workers.c
+++ b/mono/sgen/sgen-workers.c
@@ -59,7 +59,11 @@ enum {
 typedef gint32 State;
 
 static SgenObjectOperations * volatile idle_func_object_ops;
-static SgenThreadPoolJob * volatile preclean_job;
+/*
+ * 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;
 
@@ -126,12 +130,13 @@ worker_try_finish (WorkerData *data)
 	}
 
 	if (working == 1) {
-		SgenThreadPoolJob *job = preclean_job;
+		SgenWorkersFinishCallback callback = finish_callback;
 		/* 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 (job) {
-			preclean_job = NULL;
-			sgen_thread_pool_job_enqueue (job);
+		if (callback) {
+			finish_callback = NULL;
+			callback ();
+			/* 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;
@@ -326,7 +331,7 @@ sgen_workers_init (int num_workers)
 void
 sgen_workers_stop_all_workers (void)
 {
-	preclean_job = NULL;
+	finish_callback = NULL;
 	mono_memory_write_barrier ();
 	forced_stop = TRUE;
 
@@ -336,11 +341,11 @@ sgen_workers_stop_all_workers (void)
 }
 
 void
-sgen_workers_start_all_workers (SgenObjectOperations *object_ops, SgenThreadPoolJob *job)
+sgen_workers_start_all_workers (SgenObjectOperations *object_ops, SgenWorkersFinishCallback callback)
 {
 	forced_stop = FALSE;
 	idle_func_object_ops = object_ops;
-	preclean_job = job;
+	finish_callback = callback;
 	mono_memory_write_barrier ();
 
 	sgen_workers_ensure_awake ();
@@ -428,4 +433,10 @@ sgen_workers_take_from_queue_and_awake (SgenGrayQueue *queue)
 	}
 }
 
+SgenObjectOperations*
+sgen_workers_get_idle_func_object_ops (void)
+{
+	return idle_func_object_ops;
+}
+
 #endif
diff --git a/mono/sgen/sgen-workers.h b/mono/sgen/sgen-workers.h
index f13444691e6..cae2da50123 100644
--- a/mono/sgen/sgen-workers.h
+++ b/mono/sgen/sgen-workers.h
@@ -12,6 +12,9 @@
 
 #include "mono/sgen/sgen-thread-pool.h"
 
+
+typedef void (*SgenWorkersFinishCallback) (void);
+
 typedef struct _WorkerData WorkerData;
 struct _WorkerData {
 	gint32 state;
@@ -20,7 +23,7 @@ struct _WorkerData {
 
 void sgen_workers_init (int num_workers);
 void sgen_workers_stop_all_workers (void);
-void sgen_workers_start_all_workers (SgenObjectOperations *object_ops, SgenThreadPoolJob *finish_job);
+void sgen_workers_start_all_workers (SgenObjectOperations *object_ops, SgenWorkersFinishCallback finish_job);
 void sgen_workers_init_distribute_gray_queue (void);
 void sgen_workers_enqueue_job (SgenThreadPoolJob *job, gboolean enqueue);
 void sgen_workers_wait_for_jobs_finished (void);
@@ -32,5 +35,6 @@ gboolean sgen_workers_all_done (void);
 gboolean sgen_workers_are_working (void);
 void sgen_workers_assert_gray_queue_is_empty (void);
 void sgen_workers_take_from_queue_and_awake (SgenGrayQueue *queue);
+SgenObjectOperations* sgen_workers_get_idle_func_object_ops (void);
 
 #endif