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Re: AutoFDO profile toolchain is open-sourced
- From: Dehao Chen <dehao at google dot com>
- To: Andi Kleen <andi at firstfloor dot org>
- Cc: Ilya Palachev <i dot palachev at samsung dot com>, Diego Novillo <dnovillo at google dot com>, GCC Development <gcc at gcc dot gnu dot org>, David Li <davidxl at google dot com>, Jan Hubicka <hubicka at ucw dot cz>, Sebastian Pop <sebpop at gmail dot com>, Vyacheslav Barinov <v dot barinov at samsung dot com>
- Date: Tue, 21 Apr 2015 08:43:44 -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> <552E1613 dot 2040405 at samsung dot com> <5536278E dot 3090706 at samsung dot com> <CAD_=9DQEqCqzyBKT8nZ1_uEt5gU589hSpLiOHUqLXKctJTaVHA at mail dot gmail dot com> <553653CA dot 9070009 at samsung dot com> <87wq15mud5 dot fsf at tassilo dot jf dot intel dot com>
On Tue, Apr 21, 2015 at 7:25 AM, Andi Kleen <andi@firstfloor.org> wrote:
> Ilya Palachev <i.palachev@samsung.com> writes:
>>
>> But why create_gcov does not inform about that (no branch events were
>> found)? It creates empty gcov file and says nothing :(
>>
>> Moreover, in the mentioned README it is said that perf should also be
>> executed with option -e BR_INST_RETIRED:TAKEN.
>
> Standard perf doesn't have a full event list
> This assumes a perf patched with the libpfm patch.
>
> Also I suspect it really wants to use PEBS events, so pp should be added.
>
> Alternatively you can use ocperf (from
> http://github.com/andikleen/pmu-tools) which is just a wrapper:
>
> ocperf.py record -e br_inst_retired.near_taken:pp -b ...
>
> or specify the event manually (depending on your CPU, like)
>
> perf record -e
> cpu/event=0xc4,umask=0x20,name=br_inst_retired_near_taken,period=400009/pp
> -b ...
>
> BTW the biggest problem with autofdo currently is that it is
> quite bitrotten and supports only several years old perf.
> So all of this above will only work with old distributions,
> unless you compile an old perf utility first.
Do you mean newer perf does not support LBR (-b) any more?
Dehao
>
> -Andi
>
> --
> ak@linux.intel.com -- Speaking for myself only