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Re: [PATCH 1/5] Add gcc-auto-profile script
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Andi Kleen <andi at firstfloor dot org>
- Cc: gcc-patches at gcc dot gnu dot org, Andi Kleen <ak at linux dot intel dot com>
- Date: Mon, 30 May 2016 02:39:06 +0200
- Subject: Re: [PATCH 1/5] Add gcc-auto-profile script
- Authentication-results: sourceware.org; auth=none
- References: <1463848586-19259-1-git-send-email-andi at firstfloor dot org> <1463848586-19259-2-git-send-email-andi at firstfloor dot org>
Andi,
thanks a lot for working on the auto-fdo bootstrap. It is badly needed to
have some coverage for this feature. I don't think I can approve the
build machinery changes.
> From: Andi Kleen <ak@linux.intel.com>
>
> Using autofdo is currently something difficult. It requires using the
> model specific branches taken event, which differs on different CPUs.
> The example shown in the manual requires a special patched version of
> perf that is non standard, and also will likely not work everywhere.
>
> This patch adds a new gcc-auto-profile script that figures out the
> correct event and runs perf.
>
> This is needed to actually make use of autofdo in a generic way
> in the build system and in the test suite.
>
> Since maintaining the script would be somewhat tedious (needs changes
> every time a new CPU comes out) I auto generated it from the online
> Intel event database. The script to do that is in contrib and can be
> rerun.
I guess we need to figure out how to ship this to users. At the moment
the script will tell you to rebuild when it meets new CPU, but it reffers
to gcc sources which is not the best place.
Also the script should insteall when it is documented in invoke.texi
What happens when you ahve wrong perf?
Honza