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

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Message-ID: <Z4vyvNChyXZx33xf@google.com>
Date: Sat, 18 Jan 2025 10:28:12 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Howard Chu <howardchu95@...il.com>, 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

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