Re: [PATCH] perf test: Restore sample rate for perf_event_attr

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Tue, Oct 01, 2024 at 10:31:38AM +0200, Veronika Molnarova wrote:
> Ping
> 
> On 8/28/24 15:46, vmolnaro@redhat.com wrote:
> > From: Veronika Molnarova <vmolnaro@redhat.com>
> > 
> > Test "Setup struct perf_event_attr" consists of multiple test cases that
> > can affect the max sample rate value for perf events. Some test cases
> > check this value as it should not be lowered under the set minimum for
> > the given test. Currently, it is possible for the test cases to affect
> > each other as the previous tests can lower the sample rate, leading to
> > a possible failure of some of the future test cases as the value is not
> > restored at any point.
> > 
> >  10: Setup struct perf_event_attr:
> > --- start ---
> > test child forked, pid 104220
> > Using CPUID 0x00000000413fd0c1
> > running './tests/attr/test-record-C0'
> > Current sample rate: 10000
> > running './tests/attr/test-record-basic'
> > Current sample rate: 900
> > running './tests/attr/test-record-branch-any'
> > Current sample rate: 600
> > running './tests/attr/test-record-dummy-C0'
> > Current sample rate: 600
> > expected sample_period=4000, got 600
> > FAILED './tests/attr/test-record-dummy-C0' - match failure

Please indent the shell output or source code by at least 2 spaces so
that git can distinguish it from other messages.  Typical problems are
having '#' at the beginning of a line.

In this case, '---' in the test output makes it think the rest is a
comment and ignored the messages.

Can you please resend with the change?

Thanks,
Namhyung

> > 
> > Restore the max sample rate value for perf events to a reasonable value
> > before each test case if its value was lowered too much to ensure the
> > same conditions for each test case.
> > 
> >  10: Setup struct perf_event_attr:
> > --- start ---
> > test child forked, pid 107222
> > Using CPUID 0x00000000413fd0c1
> > running './tests/attr/test-record-C0'
> > Current sample rate: 10000
> > running './tests/attr/test-record-basic'
> > Current sample rate: 800
> > running './tests/attr/test-record-branch-any'
> > Current sample rate: 700
> > unsupp  './tests/attr/test-record-branch-any'
> > running './tests/attr/test-record-branch-filter-any'
> > Current sample rate: 10000
> > running './tests/attr/test-record-count'
> > Current sample rate: 10000
> > running './tests/attr/test-record-data'
> > Current sample rate: 600
> > running './tests/attr/test-record-dummy-C0'
> > Current sample rate: 800
> > running './tests/attr/test-record-freq'
> > Current sample rate: 10000
> > ...
> > 
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> > Cc: Ian Rogers <irogers@google.com>
> > Cc: Jiri Olsa <jolsa@kernel.org>
> > Cc: Kan Liang <kan.liang@linux.intel.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Michael Petlan <mpetlan@redhat.com>
> > Cc: Radostin Stoyanov <rstoyano@redhat.com>
> > Signed-off-by: Veronika Molnarova <vmolnaro@redhat.com>
> > ---
> >  tools/perf/tests/attr.py | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> > 
> > diff --git a/tools/perf/tests/attr.py b/tools/perf/tests/attr.py
> > index e890c261ad26..3db9a7d78715 100644
> > --- a/tools/perf/tests/attr.py
> > +++ b/tools/perf/tests/attr.py
> > @@ -246,6 +246,23 @@ class Test(object):
> >                  return False
> >          return True
> >  
> > +    def restore_sample_rate(self, value=10000):
> > +        try:
> > +            # Check value of sample_rate
> > +            with open("/proc/sys/kernel/perf_event_max_sample_rate", "r") as fIn:
> > +                curr_value = fIn.readline()
> > +            # If too low restore to reasonable value
> > +            if not curr_value or int(curr_value) < int(value):
> > +                with open("/proc/sys/kernel/perf_event_max_sample_rate", "w") as fOut:
> > +                    fOut.write(str(value))
> > +
> > +        except IOError as e:
> > +            log.warning("couldn't restore sample_rate value: I/O error %s" % e)
> > +        except ValueError as e:
> > +            log.warning("couldn't restore sample_rate value: Value error %s" % e)
> > +        except TypeError as e:
> > +            log.warning("couldn't restore sample_rate value: Type error %s" % e)
> > +
> >      def load_events(self, path, events):
> >          parser_event = configparser.ConfigParser()
> >          parser_event.read(path)
> > @@ -283,6 +300,7 @@ class Test(object):
> >          if self.skip_test_kernel_until():
> >              raise Notest(self, "new kernel skip")
> >  
> > +        self.restore_sample_rate()
> >          cmd = "PERF_TEST_ATTR=%s %s %s -o %s/perf.data %s" % (tempdir,
> >                self.perf, self.command, tempdir, self.args)
> >          ret = os.WEXITSTATUS(os.system(cmd))
>