On Thu, Jan 16, 2020 at 10:25 AM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Thu, Jan 16, 2020 at 10:06 AM Yonghong Song <yhs@xxxxxx> wrote:
> >
> > Alexei observed that test_progs send_signal may fail if run
> > with command line "./test_progs" and the tests will pass
> > if just run "./test_progs -n 40".
> >
> > I observed similar issue with nmi subtest failure
> > and added a delay 100 us in Commit ab8b7f0cb358
> > ("tools/bpf: Add self tests for bpf_send_signal_thread()")
> > and the problem is gone for me. But the issue still exists
> > in Alexei's testing environment.
> >
> > The current code uses sample_freq = 50 (50 events/second), which
> > may not be enough. But if the sample_freq value is larger than
> > sysctl kernel/perf_event_max_sample_rate, the perf_event_open
> > syscall will fail.
> >
> > This patch changed nmi perf testing to use sample_period = 1,
> > which means trying to sampling every event. This seems fixing
> > the issue.
> >
> > Fixes: ab8b7f0cb358 ("tools/bpf: Add self tests for bpf_send_signal_thread()")
> > Signed-off-by: Yonghong Song <yhs@xxxxxx>
> > ---
>
> Good not to have to rely on arbitrary timeout!
Indeed.
Applied. Thanks
