[Bug bootstrap/109310] New: --enable-link-mutex is quite duplicate to --enable-link-serialization

[Bug bootstrap/109310] New: --enable-link-mutex is quite duplicate to --enable-link-serialization

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109310

            Bug ID: 109310
           Summary: --enable-link-mutex is quite duplicate to
                    --enable-link-serialization
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org, rguenth at gcc dot gnu.org
  Target Milestone: ---

As mentioned in PR96794, --enable-link-mutex is problematic from LTO point of
view as each linker invocation holds a jobserver token, and thus LTRANS phase
runs with a limited number of jobs.

On the other hand, --enable-link-serialization works fine:
https://gist.githubusercontent.com/marxin/13895e6614c1d73301d05005ed4475b7/raw/bc5eb701024f3d0b912e4e3fb58b96e7abae327c/gcc13-serial-linking.svg

So my question is if we can drop --enable-link-mutex? Note the
--enable-link-serialization option is more generic as it accepts an option
argument (N).

I see only a minimal benefit of --enable-link-mutex and that's the fact it
periodically prints a message that it attempts to acquire a lock. That can be
useful for builder timeout when it comes to a very slow machine. But still, we
should be able to link a FE in a reasonable amount of time.

Jakub, what do you think?

[Bug bootstrap/109310] --enable-link-mutex is quite duplicate to --enable-link-serialization

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109310

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So perhaps for GCC13 emit some kind of deprecation message for it and suggest
using --enable-link-serialization instead and delete later?

[Bug bootstrap/109310] --enable-link-mutex is quite duplicate to --enable-link-serialization

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109310

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-03-29
           Keywords|                            |patch

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #1)
> So perhaps for GCC13 emit some kind of deprecation message for it and
> suggest using --enable-link-serialization instead and delete later?

Yes, I've just sent a patch:
https://gcc.gnu.org/pipermail/gcc-patches/2023-March/614841.html

[Bug bootstrap/109310] --enable-link-mutex is quite duplicate to --enable-link-serialization

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109310

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Martin Liska <marxin@gcc.gnu.org>:

https://gcc.gnu.org/g:8b2766e87dbf0d20808bc92d8e6ee7f876d19ab2

commit r13-6929-g8b2766e87dbf0d20808bc92d8e6ee7f876d19ab2
Author: Martin Liska <mliska@suse.cz>
Date:   Wed Mar 29 14:52:42 2023 +0200

    configure: deprecate --enable-link-mutex option

            PR bootstrap/109310

    gcc/ChangeLog:

            * configure.ac: Emit a warning for deprecated option
            --enable-link-mutex.
            * configure: Regenerate.