From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Yonghong Song <yhs@fb.com>, bpf <bpf@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next] selftests/bpf: fix test_progs send_signal flakiness with nmi mode
Date: Thu, 16 Jan 2020 13:31:54 -0800 [thread overview]
Message-ID: <CAADnVQJRD1Wb6rhwfx1Te6oyAfpAk_A8fuM7T5FPicv9Z7mckA@mail.gmail.com> (raw)
In-Reply-To: <CAEf4Bzbi0T5P=Dnja=pz3Nj0jhO9S+q_q1U4vfBwYP8enX+Zag@mail.gmail.com>
On Thu, Jan 16, 2020 at 10:25 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Jan 16, 2020 at 10:06 AM Yonghong Song <yhs@fb.com> 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@fb.com>
> > ---
>
> Good not to have to rely on arbitrary timeout!
Indeed.
Applied. Thanks
prev parent reply other threads:[~2020-01-16 21:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 17:40 [PATCH bpf-next] selftests/bpf: fix test_progs send_signal flakiness with nmi mode Yonghong Song
2020-01-16 18:24 ` Andrii Nakryiko
2020-01-16 21:31 ` Alexei Starovoitov [this message]
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