Suspend runtime profiler as soon as we exit JS.

Suspend runtime profiler as soon as we exit JS.

Lots of web pages have really frequently firing timers that keep the
profiler thread spinning if we require a period of JS inactivity
before suspending the profiler. While it's possible to throttle it by
increasing the sleep delay and adjusting the duration of the required
inactive period, it seemed much simpler to just stop it immediately on
exiting JS.

Stopping the profiler this way effectively turned off two optimization
heuristics: 1) eager optimization (it's reset on waking up the
profiler and now the profiler wakes up much more frequently) and 2)
optimization throttling based on JS to non-JS state ratio (the ratio
is now 100%). I removed these two heuristics and found no performance
regressions so far.


R=ager@chromium.org
BUG=crbug.com/77625
TEST=none

Committed: http://code.google.com/p/v8/source/detail?r=8472

[Mads Ager (chromium), 2011-06-28 13:46:40]

LGTM!

Nice simplifications. I think we need to just try this out and keep our eyes out
for regressions.

[Kasper Lund, 2011-06-28 13:49:45]

DBC:

http://codereview.chromium.org/7274024/diff/1/src/compilation-cache.cc
File src/compilation-cache.cc (left):

http://codereview.chromium.org/7274024/diff/1/src/compilation-cache.cc#oldcod...
src/compilation-cache.cc:482: uint32_t hash = function->SourceHash();
It would be nice if you could get rid of JSFunction::SourceHash too. It's pretty
weird and AFAIK only used for this code.

[Vitaly Repeshko, 2011-06-29 15:10:32]

Thanks guys! This is now landed.


-- Vitaly

http://codereview.chromium.org/7274024/diff/1/src/compilation-cache.cc
File src/compilation-cache.cc (left):

http://codereview.chromium.org/7274024/diff/1/src/compilation-cache.cc#oldcod...
src/compilation-cache.cc:482: uint32_t hash = function->SourceHash();
On 2011/06/28 13:49:45, Kasper Lund wrote:
> It would be nice if you could get rid of JSFunction::SourceHash too. It's
pretty
> weird and AFAIK only used for this code.

Removed.