How figure out v8 execute Javascript (real-world pages) in detail, i.e. when interpret? when compile?

[michael lee]

Hi guys,

I want to find out the JavaScript execution details by V8.  Anyone knows how to  figure out  v8 execute Javascript (real-world pages) in detail, i.e. when interprets? when compiles?

For example, running a Telemetry benchmark with tracing:

 $ tools/perf/run_benchmark --browser=android-chromium smoothness.top_25_smooth --story-filter=yahoo --output-format html --output-format json 

then 4 html trace files and 1 json file are generated: 
 http___answers_yahoo_com22017-09-01_15-36-05.html 

This trace file provides the overall JavaScript execution information, but not the details.

Title	Tab.ExecuteJavaScript
User Friendly Category	other
Start	7,861.667 ms
Wall Duration	466.510 ms
Self Time	0.166 ms

How can I get the information of JavaScript execution details? Do you have any advice for this?

Thanks in advance!

Best Regards,

Michael

[Camillo Bruni]

Hi Micheal,

You have to enable additional tracing categories to get the detailed RuntimeCallStats, see this slidedeck for detailed instructions: https://docs.google.com/presentation/d/1Lq2DD28CGa7bxawVH_2OcmyiTiBn74dvC6vn2essroY/edit?usp=sharing

As for the telemetry tests, I think you'd have to manually go and change the benchmark to add the additional tracing categories.

We currently don't distinguish when optimizing/interpreted code is run, essentially this is all grouped under "JavaScript".

I hope this helps.

Cheers,

Camillo

[michael lee]

Hi Camillo,

Thanks for your reply! Now it works. As you said, add the "v8" into the categories in the measurement file in perf/measurement/.

Best Regards,

Michael