Re: [PATCH v9 9/9] perf test: Add Arm CoreSight callchain test

[Leo Yan <leo.yan@arm.com>]

On Wed, Jun 17, 2026 at 11:03:07AM +0100, James Clark wrote:

[...]

> > +	# It is safe to use 'i3i' with a three-instruction interval, since the
> > +	# workload is compiled with -O0.
> > +	perf script --itrace=g16i3il64 -i "$data" > "$script"
> 
> Is there a reason we don't generate callstacks on branch samples and use
> --itrace=g16bl64? That removes the magic number 3 and reduces the output
> file size and test runtime a bit.

I checked Intel-PT which does not generate callchain and branch stack for
branch samples. I just keep cs-etm aligned.

I can add callstack / branch stack for branch samples.

> All I had to do was copy the same "if (etm->synth_opts.callchain) { ..."
> block to cs_etm__synth_branch_sample(). It seems like the grepping doesn't
> exactly match the branch sample format so the test fails, but I'm sure that
> could be fixed.

This is likely caused by the regular expr.

> I suppose there is value in testing instruction output, but maybe we can add
> the option for users to add callstacks to branch samples, even if it's not
> tested.

I will try to update the test for branch samples.

Thanks,
Leo