[heap] Do not delay mark-compact by doing scavenge.

[heap] Do not delay mark-compact by doing scavenge.

This hack is causing false "last-resort" garbage collections.

When incremental marking is in progress and overshoots the limit,
our heuristics in the allocator request finishing the mark-compact
because V8 is in optimize-for-memory mode.

However, the mark-compact gets replaced by scavenger which leads to
retrying the allocation two times and eventually doing last resort GC
(which throws away all the marking info).


BUG=chromium:697119
Review-Url: https://codereview.chromium.org/2723003003
Cr-Commit-Position: refs/heads/master@{#43554}
Committed: https://chromium.googlesource.com/v8/v8/+/af55a29706703121f83837d0c9020649bb9ec6ce

[ulan, 2017-03-01 18:54:46]

ulan@chromium.org changed reviewers:
+ hpayer@chromium.org

[ulan, 2017-03-01 18:54:46]

PTAL. We tried to remove this in the past and had to revert (due to
regressions?). Let's try again. I'll fix regression if they show up by tweaking
the heuristics in the allocator.

[Hannes Payer (out of office), 2017-03-02 17:58:49]

lgtm

[ulan, 2017-03-02 17:59:59]

The CQ bit was checked by ulan@chromium.org

[commit-bot: I haz the power, 2017-03-02 18:00:06]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-02 18:27:50]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1488477599115750, "parent_rev":
"d003c2ad9cb2506bcdd69a1e43a87949c929e3d1", "commit_rev":
"af55a29706703121f83837d0c9020649bb9ec6ce"}

[commit-bot: I haz the power, 2017-03-02 18:27:54]

Description was changed from

==========
[heap] Do not delay mark-compact by doing scavenge.

This hack is causing false "last-resort" garbage collections.

When incremental marking is in progress and overshoots the limit,
our heuristics in the allocator request finishing the mark-compact
because V8 is in optimize-for-memory mode.

However, the mark-compact gets replaced by scavenger which leads to
retrying the allocation two times and eventually doing last resort GC
(which throws away all the marking info).


BUG=chromium:697119
==========

to

==========
[heap] Do not delay mark-compact by doing scavenge.

This hack is causing false "last-resort" garbage collections.

When incremental marking is in progress and overshoots the limit,
our heuristics in the allocator request finishing the mark-compact
because V8 is in optimize-for-memory mode.

However, the mark-compact gets replaced by scavenger which leads to
retrying the allocation two times and eventually doing last resort GC
(which throws away all the marking info).


BUG=chromium:697119

Review-Url: https://codereview.chromium.org/2723003003
Cr-Commit-Position: refs/heads/master@{#43554}
Committed:
https://chromium.googlesource.com/v8/v8/+/af55a29706703121f83837d0c9020649bb9...
==========

[commit-bot: I haz the power, 2017-03-02 18:27:55]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/af55a29706703121f83837d0c9020649bb9...