New flag is added that allows to specify CPU profiler sampling rate in microseconds as command line argument. It was tested to work fine with 100us interval(currently it is 1ms). Default values are kept the same as in the current implementation. The new implementation is enabled only on POSIX platforms which use signals to collect samples. Other platforms that pause thread being sampled are to follow.
SIGPROF signals are now sent on the profiler event processor thread to make sure that the processing thread does fall far behind the sampling.
The patch is based on the previous one that was rolled out in r13851. The main difference is that the circular queue is not modified for now.
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 probably replace 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 be 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=v8:2814
R=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/21101002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16310 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Their values are not used neither by the tick processor nor by CpuProfiler so it is just a waste of space.
TickSample used to be a transport for grabbed register values to TickSample::Trace, now they are passed in a special structure RegisterState which is allocated on the stack for the sampling period.
Some common pieces were moved from platform-dependent code into Sampler::SampleStack and TickSample::Init.
BUG=None
R=jkummerow@chromium.org, loislo@chromium.org
Review URL: https://codereview.chromium.org/18620002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15484 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
When pc is inside FunctionApply builtin function the top frame may be either
2) Internal stack frame created by FunctionApply itself.
In this case we know its caller's pc and can correctly resolve calling function.
1) Frame of the calling JavaScript function that invoked .apply(). In this case we have no practical reliable way to find out the caller's pc so we mark the caller's frame as 'unresolved'.
All this logic is implemented in ProfileGenerator. SafeStackFrameIterator is extended to provide type of the current top stack frame (iteration actually starts from the caller's frame as we know top function from pc).
BUG=252097
R=jkummerow@chromium.org, loislo@chromium.org
Review URL: https://codereview.chromium.org/18269003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15468 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This is a first step to having profiler sampler implementation in one file with platform capabilities guarded with #ifdef. Otherwise we have very similar implementations scattered over platform-*.cc files which makes it hard to see differences and make changes.
The next steps will be to merge win32, Mac OS X and Cygwin implementations into sampler.cc They suspend profiled thread instead of sending a signal but apart from that the logic is pretty much the same. Then I'm going to move sampler-related code from log.* into sampler.*
BUG=None
Review URL: https://codereview.chromium.org/13852005
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14265 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
