Allow IdleNotification to trigger Scavenges.

Allow IdleNotification to trigger Scavenges.

BUG=
R=ulan@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=23979

[Hannes Payer (out of office), 2014-09-10 14:15:06]

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

[Hannes Payer (out of office), 2014-09-10 14:15:06]

Hey Ulan,
I am not going to land this cl before we turn on the new IdleNotification in
Chrome. But this should be a first step to have Scavenge events triggered by the
IdleNotification.

[ulan, 2014-09-10 14:25:00]

Looks good! Two comments:

https://codereview.chromium.org/563493002/diff/40001/src/heap/gc-idle-time-ha...
File src/heap/gc-idle-time-handler.cc (right):

https://codereview.chromium.org/563493002/diff/40001/src/heap/gc-idle-time-ha...
src/heap/gc-idle-time-handler.cc:82: if (heap_state.available_new_space_memory <
kNewSpaceAlmostFullTreshold &&
We should also check new space size now against new space size after last idle
scavenge. So that we do not do two scavenges in a row.

https://codereview.chromium.org/563493002/diff/40001/src/heap/heap.cc
File src/heap/heap.cc (right):

https://codereview.chromium.org/563493002/diff/40001/src/heap/heap.cc#newcode...
src/heap/heap.cc:4342: CollectGarbage(NEW_SPACE, "idle notification: scavenge");
It just occurred to me that this will trigger scavenge which will increment
scavenges_since_last_idle_round_, which might trigger another idle round. So we
probably want to NotifyIdleScavenge here and decrement
scavenges_since_last_idle_round_.

[ulan, 2014-09-16 12:47:23]

lgtm

[Hannes Payer (out of office), 2014-09-16 13:00:18]

Committed patchset #4 (id:60001) manually as 23979 (presubmit successful).