linux-kernel - Re: [PATCH V2] perf test: Fix test perf stat tests for virtualized machines

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Message-ID: <CAP-5=fUrqq5fH9DRtXM0KvYhG5LWzWMf0E4r+62=kAQgbzDHAA@mail.gmail.com>
Date: Thu, 8 Jan 2026 10:03:49 -0800
From: Ian Rogers <irogers@...gle.com>
To: James Clark <james.clark@...aro.org>
Cc: Thomas Richter <tmricht@...ux.ibm.com>, agordeev@...ux.ibm.com, gor@...ux.ibm.com, 
	sumanthk@...ux.ibm.com, hca@...ux.ibm.com, japo@...ux.ibm.com, 
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, acme@...nel.org, namhyung@...nel.org
Subject: Re: [PATCH V2] perf test: Fix test perf stat tests for virtualized machines

On Wed, Jan 7, 2026 at 7:30 AM James Clark <james.clark@...aro.org> wrote:
>
>
>
> On 07/01/2026 1:32 pm, Thomas Richter wrote:
> > V1 --> V2: Add correct Fixes: tag, suggested by James Clark
> >
> > On s390 perf test 'perf stat tests', subtest test_hybrid fails
> > for z/VM systems.
> > The root cause is this statement:
> >
> >    $(perf stat -a -- sleep 0.1 2>&1 |\
> >                    grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]* -c)
> >
> > The perf stat output on a s390 z/VM system is
> >
> >   # perf stat -a -- sleep 0.1 2>&1
> >   Performance counter stats for 'system wide':
> >
> >         56      context-switches  #     46.3 cs/sec  cs_per_second
> >   1,210.41 msec cpu-clock         #     11.9 CPUs  CPUs_utilized
> >         12      cpu-migrations    #      9.9 migrations/sec ...
> >         81      page-faults       #     66.9 faults/sec ...
> >
> >         0.100891009 seconds time elapsed
> >
> > The grep command does not match any single line and exits with error
> > code 1. As the bash script is executed with set -e, it aborts with the
> > first error code being non-zero.
> >
> > Fix this and use wc -l to count matching lines instead of grep ... -c.
> >
> > Output before:
> >   # perf test 102
> >   102: perf stat tests                      : FAILED!
> >   #
> > Output after:
> >   # perf test 102
> >   102: perf stat tests                      : Ok
> >   #
> >
> > Fixes: bb6e7cb11d97c ("perf tools: Add fallback for exclude_guest")
> > Cc: James Clark <james.clark@...aro.org>
> > Cc: Ian Rogers <irogers@...gle.com>
> > Cc: Namhyung Kim <namhyung@...nel.org>
> > Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
> > ---
> >   tools/perf/tests/shell/stat.sh | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/tests/shell/stat.sh b/tools/perf/tests/shell/stat.sh
> > index 0b2f0f88ca16..792a0b79f6b8 100755
> > --- a/tools/perf/tests/shell/stat.sh
> > +++ b/tools/perf/tests/shell/stat.sh
> > @@ -233,7 +233,7 @@ test_hybrid() {
> >     fi
> >
> >     # Run default Perf stat
> > -  cycles_events=$(perf stat -a -- sleep 0.1 2>&1 | grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]*  " -c)
> > +  cycles_events=$(perf stat -a -- sleep 0.1 2>&1 | grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]*  "  | wc -l)
> >
> >     # The expectation is that default output will have a cycles events on each
> >     # hybrid PMU. In situations with no cycles PMU events, like virtualized, this
>
> Reviewed-by: James Clark <james.clark@...aro.org>

Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian