RFR: 7903696: JMH: Add xctrace-based perfasm profiler for macOS [v3]

[Filipp Zhinkin]

On Fri, 19 Apr 2024 17:45:19 GMT, Dmitry Tsitelov <duke at openjdk.org> wrote:

>>> Could you add any hints for an early adopter on how to check it from a development branch?
>> 
>> Look at PR body, "Reviewing", there is a section how to fetch the dev-branch.
>
>> > Could you add any hints for an early adopter on how to check it from a development branch?
>> 
>> Look at PR body, "Reviewing", there is a section how to fetch the dev-branch.
> 
> Thank you for the hint, Alexey. 
> My question was mostly about the prerequisites required to use the xctrace profiling feature:
> - do I need to install any prerequisites except XCode?
> - shall I create some specific instruments.app profile? 
> 
> Extra: can Instruments' CPU counters facility be used to profile cache misses and so on?

@tsitelov, first of all, thanks for your interest in the profiler!

> My question was mostly about the prerequisites required to use the xctrace profiling feature:
> 
> - do I need to install any prerequisites except XCode?
> - shall I create some specific instruments.app profile?

`Xcode` is the only prerequisite. You can use either `Time Profiler` (it will be used by default) or `CPU Profiler` templates without configuring anything in the `Instruments.app`. A template name could be specified using `template` parameter.

> Extra: can Instruments' CPU counters facility be used to profile cache misses and so on?

In that case you have to configure and save a new template in the `Instruments.app` and then supply its name or a path to it to xctraceprof's `template` parameter. The only caveat is that the same PMU counter should be configured as both a PMI trigger and a sampled event in Instrument's recording settings.

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PR Comment: https://git.openjdk.org/jmh/pull/130#issuecomment-2067089169