Re: [PATCH 7/9] perf test cs-etm: Test branch history on existing samples

Thank you for your contribution! Sashiko AI review found 1 potential issue(=
s) to consider:
- [Medium] `check_callchains` does not verify callchains for each process a=
s claimed in the commit message.
--

--- Patch [7]: [PATCH 7/9] perf test cs-etm: Test branch history on existin=
g samples ---
commit e252ec70028dd10b925f2e4ea78b626688f184d4
Author: Amir Ayupov <[email protected]>

perf test cs-etm: Test branch history on existing samples

This commit adds a CoreSight shell test to verify branch history on existing
samples using explicitly timestamped ETM traces. It decodes traces with L4 =
and
L64 depth settings and checks that pause samples contain valid multi-frame
callchains and bounded branch stacks.

> diff --git a/tools/perf/tests/shell/coresight/add_last_branch.sh b/tools/=
perf/tests/shell/coresight/add_last_branch.sh
> new file mode 100755
> --- /dev/null
> +++ b/tools/perf/tests/shell/coresight/add_last_branch.sh

[ ... ]

> +check_callchains()
> +{
> +	local output=3D"$tmpdir/script-callchain"
> +
> +	perf script -i "$tmpdir/data" -F comm,event,ip >"$output" 2>/dev/null
> +
> +	awk '
> +		/cycles\/aux-action=3Dpause/ {
> +			in_sample =3D 1
> +			frames =3D 0
> +			next
> +		}
> +		!NF {
> +			if (in_sample && frames >=3D 2)
> +				found =3D 1
> +			in_sample =3D 0
> +			next
> +		}

[Severity: Medium]
The commit message states the test will "check that the pause samples carry
both a multi-frame callchain and a non-empty branch stack for each of the
workload's two processes."

Does this awk script in check_callchains() verify the callchains for each
process?

Unlike check_process_samples(), which checks for proc1 and proc2, this
script appears to set found=3D1 as soon as any sample contains a multi-frame
callchain, without validating the comm field.

--=20
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