Oilpan: tweak heuristics for forcing conservative GC.

Oilpan: tweak heuristics for forcing conservative GC.

Keep track of collection rate. If we collect less than 50% of objects,
use a factor of 4 instead of 2 allocation to force conservative GCs.

This will only have an effect when you do not get back to the event
loop in a timely manner. That happens a lot in benchmarks and almost
never in reality.

R=erik.corry@gmail.com, zerny@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=179949

[Erik Corry, 2014-08-11 10:24:06]

lgtm

https://codereview.chromium.org/460593002/diff/1/Source/platform/heap/ThreadS...
File Source/platform/heap/ThreadState.cpp (right):

https://codereview.chromium.org/460593002/diff/1/Source/platform/heap/ThreadS...
Source/platform/heap/ThreadState.cpp:627: // but not for less than 4Mbytes.
// If we are in low collection rate mode, then require a 300% increase in size.

[zerny-chromium, 2014-08-11 10:29:42]

lgtm

[haraken, 2014-08-11 10:46:14]

LGTM

[Mads Ager (chromium), 2014-08-11 12:21:31]

https://codereview.chromium.org/460593002/diff/1/Source/platform/heap/ThreadS...
File Source/platform/heap/ThreadState.cpp (right):

https://codereview.chromium.org/460593002/diff/1/Source/platform/heap/ThreadS...
Source/platform/heap/ThreadState.cpp:627: // but not for less than 4Mbytes.
On 2014/08/11 10:24:06, Erik Corry wrote:
> // If we are in low collection rate mode, then require a 300% increase in
size.

Done.

[Mads Ager (chromium), 2014-08-11 12:21:34]

The CQ bit was checked by ager@chromium.org

[commit-bot: I haz the power, 2014-08-11 12:22:34]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ager@chromium.org/460593002/20001

[commit-bot: I haz the power, 2014-08-11 13:35:02]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/22045)

[commit-bot: I haz the power, 2014-08-11 14:10:09]

Change committed as 179949