Re: [PATCH v2 4/4] perf test: Don't starve per-process tests with system-wide events

[sashiko-bot@kernel.org]

> Some tests intermittently fail when run in parallel, for example "Check
> branch stack sampling" fails with no branches recorded at all.
> 
> The default event is cycles:P which there may only be 1 or 2 HW counters
> for on Intel because it's precise. System wide or per-core precise
> events hog the HW counter leaving other per-process tests with no
> samples. Rather than make all the tests that use default record commands
> run serially, just make the system wide ones use a software event which
> has the greatest possible compatibility. They don't need precise
> sampling or HW counters anyway. The per-process tests can be left alone
> as their events/processes never run concurrently on any one core.
> 
> The LBR filter is another resource shared by all events on a CPU, and
> the system-wide LBR test uses different filters to the per-process
> branch stack test, so mark the LBR test as exclusive.
> [ ... ]
>   ...
>   ---- end(-1) ----
>   138: Check branch stack sampling : FAILED!
> 
> Signed-off-by: James Clark <james.clark@linaro.org>

Sashiko has reviewed this patch and found no issues.

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