Re: [PATCH] perf tools: Stop depending on .git files for building PERF-VERSION-FILE

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Wed, Mar 30, 2022 at 04:22:35PM +0200, Matthieu Baerts escreveu:
> Hi Arnaldo,
> 
> On 30/03/2022 16:12, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Mar 30, 2022 at 03:22:37PM +0200, Matthieu Baerts escreveu:
> >> Hi John,
> >>
> >> On 30/03/2022 12:22, John Garry wrote:
> >>> This essentially reverts commit c72e3f04b45fb2e50cdd81a50c3778c6a57251d8
> >>> and commit 4e666cdb06eede2069a7b1a96a1359d1c441a3eb.
> >>>
> >>> In commit c72e3f04b45f ("tools/perf/build: Speed up git-version test on
> >>> re-make"), a makefile dependency on .git/HEAD was added. The background is
> >>> that running PERF-VERSION-FILE is relatively slow, and commands like
> >>> "git describe" are particularly slow.
> >>>
> >>> In commit 4e666cdb06ee ("perf tools: Fix dependency for version file
> >>> creation"), an additional dependency on .git/ORIG_HEAD was added, as
> >>> .git/HEAD may not change for "git reset --hard HEAD^" command. However,
> >>> depending on whether we're on a branch or not, a "git cherry-pick" may
> >>> not lead to the version being updated.
> >>>
> >>> As discussed with the git community in [0], using git internal files for
> >>> dependencies is not reliable. Commit 4e666cdb06ee also breaks some build
> >>> scenarios [1].
> >>>
> >>> As mentioned, c72e3f04b45f was added to speed up the build. However in
> >>> commit 7572733b8499 ("perf tools: Fix version kernel tag") we removed the
> >>> call to "git describe", so just revert Makefile.perf back to same as pre
> >>> c72e3f04b45f and the build should not be so slow, as below:
> >>>
> >>> Pre 7572733b8499:
> >>> $> time util/PERF-VERSION-GEN
> >>>   PERF_VERSION = 5.17.rc8.g4e666cdb06ee
> >>>
> >>> real    0m0.110s
> >>> user    0m0.091s
> >>> sys     0m0.019s
> >>>
> >>> Post 7572733b8499:
> >>> $> time util/PERF-VERSION-GEN
> >>>   PERF_VERSION = 5.17.rc8.g7572733b8499
> >>>
> >>> real    0m0.039s
> >>> user    0m0.036s
> >>> sys     0m0.007s
> >>>
> >>> [0] https://lore.kernel.org/git/87wngkpddp.fsf@igel.home/T/#m4a4dd6de52fdbe21179306cd57b3761eb07f45f8
> >>> [1] https://lore.kernel.org/linux-perf-users/20220329093120.4173283-1-matthieu.baerts@tessares.net/T/#u
> >>>
> >>> Fixes: 4e666cdb06ee ("perf tools: Fix dependency for version file creation")
> >>> Reported-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> >>> Signed-off-by: John Garry <john.garry@huawei.com>
> >>
> >> Thank you for your patch, I just tested it and it also fixes the issue I
> >> reported!
> > 
> > I'm taking this as a:
> > 
> > Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> > 
> > Ok?
> 
> Yes, OK for me, thank you!
> 
> I never know what maintainers prefer when there is already a
> "Reported-by" tag so I didn't specify it but I will do next time.

Right, I'll stick both R-by and T-by.

There are cases where people just report and don't test, or just ack.

- Arnaldo