Disable page navigation GC

third_party/WebKit/Source/platform/heap/ThreadState.cpp

Index: third_party/WebKit/Source/platform/heap/ThreadState.cpp
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.cpp b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
index 2b953d83646578b3e9c5c7f0e7d59d4642783a4a..8336e8c4faef4092eff8b2fcd51bc215fbe8e06c 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -563,7 +563,10 @@ bool ThreadState::shouldScheduleV8FollowupGC()
 
 bool ThreadState::shouldSchedulePageNavigationGC(float estimatedRemovalRatio)
 {
-    return judgeGCThreshold(1024 * 1024, 1.5 * (1 - estimatedRemovalRatio));
+    // If estimatedRemovalRatio is low we should let IdleGC handle this.
+    if (estimatedRemovalRatio == 0.01)

[haraken, 2016/02/14 23:23:04]

I'm confused with this branch.

- Are you intending 'estimatedRemovalRatio < 0.01'?

- I think estimatedRemovalRatio should be renamed to estimatedLiveNodesRatio. If
so, 'estimatedLiveNodesRatio < 0.01' means that "don't schedule a page
navigation GC if # of live nodes is small". This doesn't make sense.

- 'return false' won't schedule an idle GC.

[keishi, 2016/02/15 01:40:50]

Yes, sorry.
FrameLoader is calculating (# of nodes in detaching document) / (# of nodes) so
this isn't a live node ratio.

My thinking was that PageNavigationGC has penalties like impact on PLT and jank
so we should let normal IdleGC logic handle most of the time. If the
estimatedRemovalRatio is low this isn't really a PageNavigationGC, more like a
IdleGC with the extra penalties.

I'll fix the estimatedRemovalRatio and measure some more.

+        return false;
+    return judgeGCThreshold(32 * 1024 * 1024, 1.5 * (1 - estimatedRemovalRatio));
 }
 
 bool ThreadState::shouldForceConservativeGC()
@@ -660,7 +663,6 @@ void ThreadState::schedulePageNavigationGCIfNeeded(float estimatedRemovalRatio)
         dataLogF("Scheduled PageNavigationGC\n");
 #endif
         schedulePageNavigationGC();
-        return;
     }
 }