Send SIGPROF signals on the profiler event processor thread

Send SIGPROF signals on the profiler event processor thread

The patch is based on the previous one that was rolled out: https://code.google.com/p/v8/source/detail?r=12985

On Linux sampling for CPU profiler is initiated on the profiler event processor thread, other platforms to follow.

CPU profiler continues to use SamplingCircularQueue, we will replave it with a single sample buffer when Mac and Win ports support profiling on the event processing thread.

When --prof option is specified profiling is initiated either on the profiler event processor thread if CPU profiler is on or on the  SignalSender thread as it used to if no CPU profiles are being collected.

ProfilerEventsProcessor::ProcessEventsAndDoSample now waits in a tight loop, processing collected samples until sampling interval expires. To save CPU resources I'm planning to change that to use nanosleep as only one sample is expected in the queue at any point.

BUG=v8:2364
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=13735

[loislo, 2013-02-21 12:42:39]

https://codereview.chromium.org/12321046/diff/2001/src/circular-queue.cc
File src/circular-queue.cc (right):

https://codereview.chromium.org/12321046/diff/2001/src/circular-queue.cc#newc...
src/circular-queue.cc:39: int producer_consumer_distance)
I'd pass a boolean or enum flag instead of a magic variable.

[yurys, 2013-02-21 12:45:48]

https://codereview.chromium.org/12321046/diff/2001/src/circular-queue.cc
File src/circular-queue.cc (right):

https://codereview.chromium.org/12321046/diff/2001/src/circular-queue.cc#newc...
src/circular-queue.cc:39: int producer_consumer_distance)
On 2013/02/21 12:42:39, loislo wrote:
> I'd pass a boolean or enum flag instead of a magic variable.

Done.

[Jakob Kummerow, 2013-02-21 13:32:17]

LGTM with a nit.

https://codereview.chromium.org/12321046/diff/5002/src/platform.h
File src/platform.h (right):

https://codereview.chromium.org/12321046/diff/5002/src/platform.h#newcode797
src/platform.h:797: static bool CanSampleOnProflerEventsProcessorThread();
s/Profler/Profiler/

[yurys, 2013-02-21 13:45:40]

https://codereview.chromium.org/12321046/diff/5002/src/platform.h
File src/platform.h (right):

https://codereview.chromium.org/12321046/diff/5002/src/platform.h#newcode797
src/platform.h:797: static bool CanSampleOnProflerEventsProcessorThread();
On 2013/02/21 13:32:17, Jakob wrote:
> s/Profler/Profiler/

Done.

[yurys, 2013-02-26 16:15:47]

Committed patchset #4 manually as r13735 (presubmit successful).