This is the mail archive of the
mailing list for the GCC project.
Re: AutoFDO profile toolchain is open-sourced
- From: Xinliang David Li <davidxl at google dot com>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: Ilya Palachev <i dot palachev at samsung dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, Vyacheslav Barinov <v dot barinov at samsung dot com>, Diego Novillo <dnovillo at google dot com>, Sebastian Pop <sebpop at gmail dot com>, Dehao Chen <dehao at google dot com>
- Date: Fri, 10 Apr 2015 15:49:33 -0700
- Subject: Re: AutoFDO profile toolchain is open-sourced
- Authentication-results: sourceware.org; auth=none
- References: <CAO2gOZWydpiBXb=1QDyCRt-ybDieqy8X4S_+uRZk2Y2v+cFdYQ at mail dot gmail dot com> <5523ED98 dot 8080007 at samsung dot com> <CAFk3UF8To5Qcz8NN5rUF3z6j8CCg_89A+62P=1U9YrtbZ5=mLg at mail dot gmail dot com> <20150410203927 dot GA18980 at atrey dot karlin dot mff dot cuni dot cz> <CAAkRFZ+2RK=-qKo4eCRmq0N1QjENm0tAe2PbX3xnC76UyuFrJA at mail dot gmail dot com> <CAAkRFZLMP3SvGZqCdyLbnZqfY6RUqwRJ3tpVRYKMA+ZCVt2u9A at mail dot gmail dot com> <20150410224327 dot GA87750 at kam dot mff dot cuni dot cz>
On Fri, Apr 10, 2015 at 3:43 PM, Jan Hubicka <email@example.com> wrote:
>> LBR is used for both cfg edge profiling and indirect call Target value
> I see, that makes sense ;) I guess if we want to support profile collection
> on targets w/o this feature we could still use one of the algorithms that
> try to guess edge profile from BB profile.
Our experience with sampling cycles or retired instructions to guess
BB profile has not been great -- the profile quality is significantly
worse than LBR (which can almost match instrumentation based profile).