linux-kernel - Re: [PATCH v4 0/2] perf trace: Add more tests for BTF-augmented perf trace

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Message-ID: <CAH0uvoiRTnT-=EeK1z6BajB9RE5F=f2S4e5a5ygo8kebyKyCqw@mail.gmail.com>
Date: Tue, 21 Jan 2025 16:19:35 -0800
From: Howard Chu <howardchu95@...il.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>, mark.rutland@....com, 
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org, irogers@...gle.com, 
	adrian.hunter@...el.com, kan.liang@...ux.intel.com, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/2] perf trace: Add more tests for BTF-augmented perf trace

Hello Namhyung,

On Sat, Jan 18, 2025 at 10:28 AM Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Mon, Jan 13, 2025 at 12:57:23PM -0300, Arnaldo Carvalho de Melo wrote:
> > On Fri, Jan 10, 2025 at 04:52:08PM -0800, Howard Chu wrote:
> > > Hello Arnaldo,
> > >
> > > On Mon, Dec 23, 2024 at 11:40 AM Arnaldo Carvalho de Melo
> > > <acme@...nel.org> wrote:
> > > >
> > > > On Mon, Dec 23, 2024 at 04:02:43PM -0300, Arnaldo Carvalho de Melo wrote:
> > > > > On Mon, Dec 16, 2024 at 11:58:46AM -0800, Namhyung Kim wrote:
> > > > > > On Sun, Dec 15, 2024 at 11:07:09AM -0800, Howard Chu wrote:
> > > > > > > Changes in v4:
> > > > > > >  - Use if -f to check the existence of vmlinux BTF, and exit if it
> > > > > > >    doesn't, so trace_test_string will not overwrite $err, and keep
> > > > > > >    running the test.
> > > > > > >
> > > > > > > Changes in v3:
> > > > > > >  - Add vmlinux BTF check, and skip the tests if it doesn't exist
> > > > > > >
> > > > > > > v1, v2:
> > > > > > >
> > > > > > > The previous version of the perf trace BTF general augmentation tests
> > > > > > > didn't pass Shellcheck (thanks to Arnaldo Carvalho de Melo
> > > > > > > <acme@...nel.org> for pointing this out), this version uses bash instead
> > > > > > > of POSIX shell to pass Shellcheck.
> > > > > > >
> > > > > > > This patch series also adds documentation for the new option
> > > > > > > --force-btf, which is used in the tests.
> > > > > > >
> > > > > > > Link: https://lore.kernel.org/linux-perf-users/Zt9yiQq-n-W6I274@x1/
> > > > > > >
> > > > > > > Howard Chu (2):
> > > > > > >   perf trace: Add tests for BTF general augmentation
> > > > > > >   perf docs: Add documentation for --force-btf option
> > > > > >
> > > > > > Acked-by: Namhyung Kim <namhyung@...nel.org>
> > > > >
> > > > > Thanks, applied to perf-tools-next,
> > > >
> > > > It fails when running in parallel mode, sometimes:
> > > >
> > > > 109: perf trace BTF general tests                                    : FAILED!
> > > >
> > > > Then:
> > > >
> > > > root@...ber:~# perf stat --null -r 10 perf test "BTF general"
> > > > 109: perf trace BTF general tests                                    : Ok
> > > > 109: perf trace BTF general tests                                    : Ok
> > > > 109: perf trace BTF general tests                                    : Ok
> > > > 109: perf trace BTF general tests                                    : Ok
> > > > 109: perf trace BTF general tests                                    : FAILED!
> > > > 109: perf trace BTF general tests                                    : Ok
> > > > 109: perf trace BTF general tests                                    : Ok
> > > > 109: perf trace BTF general tests                                    : FAILED!
> > > > 109: perf trace BTF general tests                                    : Ok
> > > > 109: perf trace BTF general tests                                    : Ok
> > > >
> > > >  Performance counter stats for 'perf test BTF general' (10 runs):
> > > >
> > > >              2.148 +- 0.293 seconds time elapsed  ( +- 13.63% )
> > > >
> > > > root@...ber:~#
> > > >
> > > >
> > > > So its not just when running in paralell, anyway, its merged, we can go
> > > > on from what we got there.
> > >
> > > It never fails on my machine, I think the reason is my machine is not
> > > fully-loaded. Can you please run
> > > ```
> > > perf stat --null -r 10 perf test -vv "BTF general"
> > > ```
> > > And provide the output?
> >
> > root@...ber:~# grep -m1 'model name' /proc/cpuinfo
> > model name    : Intel(R) Core(TM) i7-14700K
> > root@...ber:~#
> >
> > root@...ber:~# perf stat --null -r 10 perf test -vv "BTF general"
> > 106: perf trace BTF general tests:
> > --- start ---
> > test child forked, pid 47824
> > Checking if vmlinux BTF exists
> > Testing perf trace's string augmentation
> > String augmentation test failed
> > ---- end(-1) ----
> > 106: perf trace BTF general tests                                    : FAILED!
> > 106: perf trace BTF general tests:
> > --- start ---
> > test child forked, pid 47842
> > Checking if vmlinux BTF exists
> > Testing perf trace's string augmentation
> > String augmentation test failed
> > ---- end(-1) ----
> > 106: perf trace BTF general tests                                    : FAILED!
> > ...
>
> I also see the failure on not fully-loaded machines (both Intel and
> AMD).
>
>   $ sudo ./perf test -v BTF
>   --- start ---
>   test child forked, pid 525025
>   Checking if vmlinux BTF exists
>   Testing perf trace's string augmentation
>   String augmentation test failed
>   ---- end(-1) ----
>   106: perf trace BTF general tests                                    : FAILED!
>
> Thanks,
> Namhyung
>

Just wondering, did you and Arnaldo apply this patch:
https://lore.kernel.org/linux-perf-users/20241213023047.541218-1-howardchu95@gmail.com/

This seems to solve the problem for me...

Thanks,
Howard