Oilpan: Remove synchronous completeSweep() from V8's minor GC prologue

Oilpan: Remove synchronous completeSweep() from V8's minor GC prologue

Running completeSweep() in the minor GC prologue can increase the time
of the minor GC, which we really should avoid because minor GCs must be super fast.

The synchronous completeSweep() was added there to collect floating garbage
in the minor GC (i.e., to collect garbage that needs a sequence of
Oilpan's GC => V8's minor GC => Oilpan's GC). However, now that the new minor GC
has been landed which is agnostic to DOM-side reachability (i.e., the minor GC
collects unomdified V8 wrappers without taking into count the DOM-side reachability),
it's possible that we don't need to worry about the floating garbage as much as before.

So this CL removes the synchronous completeSweep() from the minor GC prologue.

BUG=582831
Committed: https://crrev.com/1afa199b6e7e5c9e33b121c02c7cfe9d240e7a4a
Cr-Commit-Position: refs/heads/master@{#372919}

[haraken, 2016-02-02 02:30:45]

haraken@chromium.org changed reviewers:
+ jochen@chromium.org, sigbjornf@opera.com

[haraken, 2016-02-02 02:30:45]

Not ready for review. I'm now measuring impact on memory.top_7_stress.

[haraken, 2016-02-02 04:16:35]

On 2016/02/02 02:30:45, haraken wrote:
> Not ready for review. I'm now measuring impact on memory.top_7_stress.

I don't observe any problematic regression: http://haraken.info/a/results.html

So PTAL.

[sof, 2016-02-02 08:19:27]

lgtm

https://codereview.chromium.org/1652103003/diff/1/third_party/WebKit/Source/p...
File third_party/WebKit/Source/platform/heap/ThreadState.cpp (right):

https://codereview.chromium.org/1652103003/diff/1/third_party/WebKit/Source/p...
third_party/WebKit/Source/platform/heap/ThreadState.cpp:645: completeSweep();
Unnecessary, already done in collectGarbage().

[haraken, 2016-02-02 08:26:34]

>
https://codereview.chromium.org/1652103003/diff/1/third_party/WebKit/Source/p...
> File third_party/WebKit/Source/platform/heap/ThreadState.cpp (right):
> 
>
https://codereview.chromium.org/1652103003/diff/1/third_party/WebKit/Source/p...
> third_party/WebKit/Source/platform/heap/ThreadState.cpp:645: completeSweep();
> Unnecessary, already done in collectGarbage().

Removed.

[haraken, 2016-02-02 08:26:38]

The CQ bit was checked by haraken@chromium.org

[haraken, 2016-02-02 08:26:38]

The patchset sent to the CQ was uploaded after l-g-t-m from sigbjornf@opera.com
Link to the patchset: https://codereview.chromium.org/1652103003/#ps20001
(title: " ")

[commit-bot: I haz the power, 2016-02-02 08:26:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1652103003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1652103003/20001

[commit-bot: I haz the power, 2016-02-02 10:00:24]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-02-02 10:01:46]

Description was changed from

==========
Oilpan: Remove synchronous completeSweep() from V8's minor GC prologue

Running completeSweep() in the minor GC prologue can increase the time
of the minor GC, which we really should avoid because minor GCs must be super
fast.

The synchronous completeSweep() was added there to collect floating garbage
in the minor GC (i.e., to collect garbage that needs a sequence of
Oilpan's GC => V8's minor GC => Oilpan's GC). However, now that the new minor GC
has been landed which is agnostic to DOM-side reachability (i.e., the minor GC
collects unomdified V8 wrappers without taking into count the DOM-side
reachability),
it's possible that we don't need to worry about the floating garbage as much as
before.

So this CL removes the synchronous completeSweep() from the minor GC prologue.

BUG=582831
==========

to

==========
Oilpan: Remove synchronous completeSweep() from V8's minor GC prologue

Running completeSweep() in the minor GC prologue can increase the time
of the minor GC, which we really should avoid because minor GCs must be super
fast.

The synchronous completeSweep() was added there to collect floating garbage
in the minor GC (i.e., to collect garbage that needs a sequence of
Oilpan's GC => V8's minor GC => Oilpan's GC). However, now that the new minor GC
has been landed which is agnostic to DOM-side reachability (i.e., the minor GC
collects unomdified V8 wrappers without taking into count the DOM-side
reachability),
it's possible that we don't need to worry about the floating garbage as much as
before.

So this CL removes the synchronous completeSweep() from the minor GC prologue.

BUG=582831

Committed: https://crrev.com/1afa199b6e7e5c9e33b121c02c7cfe9d240e7a4a
Cr-Commit-Position: refs/heads/master@{#372919}
==========

[commit-bot: I haz the power, 2016-02-02 10:01:47]

Patchset 2 (id:??) landed as
https://crrev.com/1afa199b6e7e5c9e33b121c02c7cfe9d240e7a4a
Cr-Commit-Position: refs/heads/master@{#372919}