From b0a16305a8948fc939113db4a0c760859dabae70 Mon Sep 17 00:00:00 2001
From: Terrence Cole <terrence@mozilla.com>
Date: Mon, 23 Feb 2015 14:25:37 -0800
Subject: [PATCH] Bug 1135141 - Do not do background sweeping for zealous GCs
 to avoid fragmentation; r=jonco

--HG--
extra : rebase_source : 4bdc6c9af1b6a34fb7394e2f8d0c884b114b3fee
---
 js/src/jsgc.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index 5995ab666a66..1211f469c95a 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -5576,8 +5576,13 @@ GCRuntime::finishCollection(JS::gcreason::Reason reason)
     lastGCTime = currentTime;
 
     // If this is an OOM GC reason, wait on the background sweeping thread
-    // before returning to ensure that we free as much as possible.
-    if (reason == JS::gcreason::LAST_DITCH || reason == JS::gcreason::MEM_PRESSURE) {
+    // before returning to ensure that we free as much as possible. If this is
+    // a zeal-triggered GC, we want to ensure that the mutator can continue
+    // allocating on the same pages to reduce fragmentation.
+    if (reason == JS::gcreason::LAST_DITCH ||
+        reason == JS::gcreason::MEM_PRESSURE ||
+        reason == JS::gcreason::DEBUG_GC)
+    {
         gcstats::AutoPhase ap(stats, gcstats::PHASE_WAIT_BACKGROUND_THREAD);
         rt->gc.waitBackgroundSweepOrAllocEnd();
     }