Tracing function optimizations and deoptimizations in embedded v8

[Petar Dobrev]

Hi!

How would one go about obtaining function optimization and deoptimization info from an application with embedded v8? Something similar to the output that one gets from "--trace-deopt" in Chrome or node.

Are there any resources online that I could consult?

Thanks!

Petar

[Ben Noordhuis]

If you mean a programmatic API, then include/v8-profiler.h is the file
you want. I don't believe there's a way to get optimization info but
you can get the deopt and bailout reasons. (Bailout means a function
has been deoptimized and won't be optimized again.)

[Petar Dobrev]

Thanks Ben!

From what I understand, I can the deoptimization information from CpuProfileNode::GetDeoptInfos(), which in turn I get from running and stopping the profiler (CpuProfiler::StopProfiling()). This works great for me!

Just out of curiosity, is there any way to get that info as it happens, without having to start and stop the profiler?

Thanks again!

Petar

 

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[Ben Noordhuis]

On Wed, Apr 6, 2016 at 6:39 PM, Petar Dobrev <pe...@chobolabs.com> wrote:
> On Wed, Apr 6, 2016 at 12:28 PM, Ben Noordhuis <in...@bnoordhuis.nl> wrote:
>>
>> On Wed, Apr 6, 2016 at 9:57 AM, Petar Dobrev <peter....@gmail.com>
>> wrote:
>> > Hi!
>> >
>> > How would one go about obtaining function optimization and
>> > deoptimization
>> > info from an application with embedded v8? Something similar to the
>> > output
>> > that one gets from "--trace-deopt" in Chrome or node.
>> >
>> > Are there any resources online that I could consult?
>>
>> If you mean a programmatic API, then include/v8-profiler.h is the file
>> you want. I don't believe there's a way to get optimization info but
>> you can get the deopt and bailout reasons. (Bailout means a function
>> has been deoptimized and won't be optimized again.)
>>
>
> Thanks Ben!
>
> From what I understand, I can the deoptimization information from
> CpuProfileNode::GetDeoptInfos(), which in turn I get from running and
> stopping the profiler (CpuProfiler::StopProfiling()). This works great for
> me!
>
> Just out of curiosity, is there any way to get that info as it happens,
> without having to start and stop the profiler?
>
> Thanks again!
> Petar

I don't think so, I don't believe it's recorded unless the profiler is active.