linux-kernel - Re: [PATCH v2 2/5] perf record: Prevent override of attr->sample

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Date:   Fri, 11 Sep 2020 15:34:11 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v2 2/5] perf record: Prevent override of
 attr->sample_period for libpfm4 events

On Fri, Sep 4, 2020 at 11:51 AM Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
>
> Em Fri, Sep 04, 2020 at 03:50:13PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Fri, Sep 04, 2020 at 03:48:03PM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Fri, Sep 04, 2020 at 09:22:10AM -0700, Ian Rogers escreveu:
> > > > On Fri, Sep 4, 2020 at 9:03 AM Jiri Olsa <jolsa@...hat.com> wrote:
> > > > > On Thu, Sep 03, 2020 at 10:41:14PM -0700, Ian Rogers wrote:
> > > > > > On Wed, Jul 29, 2020 at 4:24 PM Ian Rogers <irogers@...gle.com> wrote:
> > > > > > > On Tue, Jul 28, 2020 at 9:10 AM Jiri Olsa <jolsa@...hat.com> wrote:
> > > > > > > > On Tue, Jul 28, 2020 at 05:59:46PM +0200, Jiri Olsa wrote:
> > > > > > > > > On Tue, Jul 28, 2020 at 01:57:31AM -0700, Ian Rogers wrote:
> > > > > > > > [jolsa@...va perf]$ sudo ./perf test 17 -v
> > > > > > > > 17: Setup struct perf_event_attr                          :
> > >
> > > > > > > > running './tests/attr/test-record-C0'
> > > > > > > > expected sample_period=4000, got 3000
> > > > > > > > FAILED './tests/attr/test-record-C0' - match failure
> > >
> > > > > > > I'm not able to reproduce this. Do you have a build configuration or
> > > > > > > something else to look at? The test doesn't seem obviously connected
> > > > > > > with this patch.
> > >
> > > > > > Jiri, any update? Thanks,
> > >
> > > > > sorry, I rebased and ran it again and it passes for me now,
> > > > > so it got fixed along the way
> > >
> > > > No worries, thanks for the update! It'd be nice to land this and the
> > > > other libpfm fixes.
> > >
> > > I applied it and it generated this regression:
> > >
> > > FAILED '/home/acme/libexec/perf-core/tests/attr/test-record-pfm-period' - match failure
> > >
> > > I'll look at the other patches that are pending in this regard to see
> > > what needs to be squashed so that we don't break bisect.
> >
> > So, more context:
> >
> > running '/home/acme/libexec/perf-core/tests/attr/test-record-pfm-period'
> > expected exclude_hv=0, got 1
> > FAILED '/home/acme/libexec/perf-core/tests/attr/test-record-pfm-period' - match failure
> > test child finished with -1
> > ---- end ----
> > Setup struct perf_event_attr: FAILED!
> > [root@...e ~]#
> >
> > Ian, can you take a look at this?
>
> Further tests I've performed:
>
>     Committer testing:
>
>     Not linking with libpfm:
>
>       # ldd ~/bin/perf | grep libpfm
>       #
>
>     Before:
>
>       # perf record -c 10000 -e cycles/period=12345/,instructions sleep 0.0001
>       [ perf record: Woken up 1 times to write data ]
>       [ perf record: Captured and wrote 0.052 MB perf.data (258 samples) ]
>       # perf evlist -v
>       cycles/period=12345/: size: 120, { sample_period, sample_freq }: 12345, sample_type: IP|TID|TIME|ID, read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
>       instructions: size: 120, config: 0x1, { sample_period, sample_freq }: 10000, sample_type: IP|TID|TIME|ID, read_format: ID, disabled: 1, inherit: 1, enable_on_exec: 1, sample_id_all: 1, exclude_guest: 1
>       #
>
>     After:
>
>       #
>       # perf record -c 10000 -e cycles/period=12345/,instructions sleep 0.0001
>       [ perf record: Woken up 1 times to write data ]
>       [ perf record: Captured and wrote 0.053 MB perf.data (284 samples) ]
>       # perf evlist -v
>       cycles/period=12345/: size: 120, { sample_period, sample_freq }: 12345, sample_type: IP|TID|TIME|ID, read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
>       instructions: size: 120, config: 0x1, { sample_period, sample_freq }: 10000, sample_type: IP|TID|TIME|ID, read_format: ID, disabled: 1, inherit: 1, enable_on_exec: 1, sample_id_all: 1, exclude_guest: 1
>       #
>
>     Linking with libpfm:
>
>       # ldd ~/bin/perf | grep libpfm
>             libpfm.so.4 => /lib64/libpfm.so.4 (0x00007f54c7d75000)
>       #
>
>       # perf record -c 10000 --pfm-events=cycles:period=77777 sleep 1
>       [ perf record: Woken up 1 times to write data ]
>       [ perf record: Captured and wrote 0.043 MB perf.data (141 samples) ]
>       # perf evlist -v
>       cycles:period=77777: size: 120, { sample_period, sample_freq }: 10000, sample_type: IP|TID|TIME, read_format: ID, disabled: 1, inherit: 1, exclude_hv: 1, mmap: 1, comm: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
>       #
>
>     After:
>
>       # perf record -c 10000 --pfm-events=cycles:period=77777 sleep 1
>       [ perf record: Woken up 1 times to write data ]
>       [ perf record: Captured and wrote 0.039 MB perf.data (19 samples) ]
>       # perf evlist -v
>       cycles:period=77777: size: 120, { sample_period, sample_freq }: 77777, sample_type: IP|TID|TIME, read_format: ID, disabled: 1, inherit: 1, exclude_hv: 1, mmap: 1, comm: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
>       #
>
Hi Arnaldo,

I've been trying to reproduce the test failure you mention and I've
not been able to. This follow up e-mail seems to show things working
as intended. Did the issue resolve itself?

Thanks,
Ian