From: Rong Xu <xur@google.com>
To: Jan Hubicka <hubicka@ucw.cz>
Cc: gcc-patches@gcc.gnu.org, davidxl@google.com, pinskia@gmail.com,
reply@codereview.appspotmail.com
Subject: Re: atomic update of profile counters (issue7000044)
Date: Fri, 28 Dec 2012 19:33:00 -0000 [thread overview]
Message-ID: <CAF1bQ=Qs8uSHmPp01vwYm-vU4XD+wYrB4cEAcAib8i7LDAS3og@mail.gmail.com> (raw)
In-Reply-To: <CAF1bQ=R7pXzBq08E7PiXKwahpM8Lx0gergnXvGtr6wk+M8-nKA@mail.gmail.com>
Hi Honza,
In the other thread of discussion (similar patch in google-4_7
branch), you said you were thinking if to let this patch into trunk in
stage 3. Can you give some update?
Thanks,
-Rong
On Fri, Dec 21, 2012 at 10:37 AM, Rong Xu <xur@google.com> wrote:
> On Fri, Dec 21, 2012 at 1:25 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>>> Hi,
>>>
>>> This patch adds support of atomic update of profiles counters. The goal is to improve
>>> the poor counter values for highly thread programs.
>>>
>>> The atomic update is under a new option -fprofile-gen-atomic=<N>
>>> N=0: default, no atomic update
>>> N=1: atomic update edge counters.
>>> N=2: atomic update some of value profile counters (currently indirect-call and one value profile).
>>> N=3: both edge counter and the above value profile counters.
>>> Other value: fall back to the default.
>>>
>>> This patch is a simple porting of the version in google-4_7 branch. It uses __atomic_fetch_add
>>> based on Andrew Pinski's suggestion. Note I did not apply to all the value profiles as
>>> the indirect-call profile is the most relevant one here.
>>>
>>> Test with bootstrap.
>>>
>>> Comments and suggestions are welcomed.
>>>
>>> Thanks,
>>>
>>> -Rong
>>>
>>>
>>> 2012-12-20 Rong Xu <xur@google.com>
>>>
>>> * libgcc/libgcov.c (__gcov_one_value_profiler_body_atomic): New
>>> function. Atomic update profile counters.
>>> (__gcov_one_value_profiler_atomic): Ditto.
>>> (__gcov_indirect_call_profiler_atomic): Ditto.
>>> * gcc/gcov-io.h: Macros for atomic update.
>>> * gcc/common.opt: New option.
>>> * gcc/tree-profile.c (gimple_init_edge_profiler): Atomic
>>> update profile counters.
>>> (gimple_gen_edge_profiler): Ditto.
>>
>> The patch looks resonable. Eventually we probably should provide rest of the value counters
>> in thread safe manner. What happens on targets not having atomic operations?
>
> From http://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html#_005f_005fsync-Builtins,
> it says:
> "If a particular operation cannot be implemented on the target
> processor, a warning is generated and a call an external function is
> generated. "
>
> So I think there will be a warning and eventually a link error of unsat.
>
> Thanks,
>
> -Rong
>
>
>>
>> Honza
next prev parent reply other threads:[~2012-12-28 19:33 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-21 6:45 Rong Xu
2012-12-21 9:25 ` Jan Hubicka
2012-12-21 18:38 ` Rong Xu
2012-12-28 19:33 ` Rong Xu [this message]
2012-12-28 19:35 ` Xinliang David Li
2013-01-03 1:16 ` Rong Xu
2013-01-03 1:25 ` Andrew Pinski
2013-01-03 1:29 ` Rong Xu
2013-01-03 1:31 ` Andrew Pinski
2013-01-03 9:05 ` Richard Biener
2013-01-04 0:42 ` Rong Xu
2013-01-07 20:36 ` Richard Henderson
2013-01-07 20:56 ` Rong Xu
2013-11-20 7:03 ` Rong Xu
2013-11-20 7:20 ` Andrew Pinski
2013-11-20 19:59 ` Rong Xu
2013-11-20 20:08 ` Andrew Pinski
2013-11-20 20:31 ` Andrew Pinski
2013-11-20 23:18 ` Joseph S. Myers
2013-11-21 0:07 ` Rong Xu
2013-11-21 0:14 ` Andrew Pinski
2013-11-21 1:24 ` Rong Xu
2014-05-26 6:01 ` Jan Hubicka
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