From: Vlad Brezae <brezaevlad@gmail.com>
Date: Fri, 7 Apr 2017 23:21:48 +0000 (+0300)
Subject: [sgen] Resize nursery according also to pause times
X-Git-Url: http://wien.tomnetworks.com/gitweb/?p=mono.git;a=commitdiff_plain;h=5c74ddb92de7e5ac9f534abd4ff50a7c692e38fc

[sgen] Resize nursery according also to pause times
---

diff --git a/mono/sgen/sgen-conf.h b/mono/sgen/sgen-conf.h
index 324009cc295..63e922c470e 100644
--- a/mono/sgen/sgen-conf.h
+++ b/mono/sgen/sgen-conf.h
@@ -211,4 +211,12 @@ typedef mword SgenDescriptor;
 #define SGEN_DEFAULT_NURSERY_SIZE	(1 << 22)
 #define SGEN_DEFAULT_NURSERY_MAX_SIZE	(1 << 25)
 
+/*
+ * We are trying to keep pauses lower than this (ms). We use it for dynamic nursery
+ * sizing heuristics. We are keeping leeway in order to be prepared for work-load
+ * variations.
+ */
+#define SGEN_MAX_PAUSE_TIME 30
+#define SGEN_MAX_PAUSE_MARGIN 0.66f
+
 #endif
diff --git a/mono/sgen/sgen-gc.c b/mono/sgen/sgen-gc.c
index 9f8a8aa63ff..2c0337d6a35 100644
--- a/mono/sgen/sgen-gc.c
+++ b/mono/sgen/sgen-gc.c
@@ -288,6 +288,9 @@ static guint64 time_major_fragment_creation = 0;
 
 static guint64 time_max = 0;
 
+static int sgen_max_pause_time = SGEN_MAX_PAUSE_TIME;
+static float sgen_max_pause_margin = SGEN_MAX_PAUSE_MARGIN;
+
 static SGEN_TV_DECLARE (time_major_conc_collection_start);
 static SGEN_TV_DECLARE (time_major_conc_collection_end);
 
@@ -1612,6 +1615,7 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
 	SgenGrayQueue gc_thread_gray_queue;
 	SgenObjectOperations *object_ops_nopar, *object_ops_par = NULL;
 	ScanCopyContext ctx;
+	int duration;
 	TV_DECLARE (atv);
 	TV_DECLARE (btv);
 	SGEN_TV_DECLARE (last_minor_collection_start_tv);
@@ -1743,7 +1747,13 @@ collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_
 	if (remset_consistency_checks)
 		sgen_check_remset_consistency ();
 
-	sgen_resize_nursery ();
+
+	TV_GETTIME (btv);
+	duration = (int)(TV_ELAPSED (last_minor_collection_start_tv, btv) / 10000);
+	if (duration > (sgen_max_pause_time * sgen_max_pause_margin))
+		sgen_resize_nursery (TRUE);
+	else
+		sgen_resize_nursery (FALSE);
 
 	/* walk the pin_queue, build up the fragment list of free memory, unmark
 	 * pinned objects as we go, memzero() the empty fragments so they are ready for the
diff --git a/mono/sgen/sgen-gc.h b/mono/sgen/sgen-gc.h
index 1a727a6d333..27727a537b6 100644
--- a/mono/sgen/sgen-gc.h
+++ b/mono/sgen/sgen-gc.h
@@ -897,7 +897,7 @@ void sgen_los_mark_mod_union_card (GCObject *mono_obj, void **ptr);
 void sgen_clear_nursery_fragments (void);
 void sgen_nursery_allocator_prepare_for_pinning (void);
 void sgen_nursery_allocator_set_nursery_bounds (char *nursery_start, size_t min_size, size_t max_size);
-void sgen_resize_nursery (void);
+void sgen_resize_nursery (gboolean need_shrink);
 mword sgen_build_nursery_fragments (GCMemSection *nursery_section, SgenGrayQueue *unpin_queue);
 void sgen_init_nursery_allocator (void);
 void sgen_nursery_allocator_init_heavy_stats (void);
diff --git a/mono/sgen/sgen-nursery-allocator.c b/mono/sgen/sgen-nursery-allocator.c
index 1452b6b7d79..53a7999a74e 100644
--- a/mono/sgen/sgen-nursery-allocator.c
+++ b/mono/sgen/sgen-nursery-allocator.c
@@ -920,7 +920,7 @@ sgen_nursery_allocator_set_nursery_bounds (char *start, size_t min_size, size_t
 }
 
 void
-sgen_resize_nursery (void)
+sgen_resize_nursery (gboolean need_shrink)
 {
 	size_t major_size;
 
@@ -938,11 +938,11 @@ sgen_resize_nursery (void)
 	 * section).
 	 */
 	if ((sgen_nursery_size * 2) < (major_size / SGEN_DEFAULT_ALLOWANCE_NURSERY_SIZE_RATIO) &&
-			(sgen_nursery_size * 2) <= sgen_nursery_max_size) {
+			(sgen_nursery_size * 2) <= sgen_nursery_max_size && !need_shrink) {
 		if ((nursery_section->end_data - nursery_section->data) == sgen_nursery_size)
 			nursery_section->end_data += sgen_nursery_size;
 		sgen_nursery_size *= 2;
-	} else if (sgen_nursery_size > (major_size / SGEN_DEFAULT_ALLOWANCE_NURSERY_SIZE_RATIO) &&
+	} else if ((sgen_nursery_size > (major_size / SGEN_DEFAULT_ALLOWANCE_NURSERY_SIZE_RATIO) || need_shrink) &&
 			(sgen_nursery_size / 2) >= sgen_nursery_min_size) {
 		sgen_nursery_size /= 2;
 	}