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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/51798] [4.7 regression] libstdc++ atomicity performance regression due to __sync_fetch_and_add
Date: Fri, 27 Jan 2012 10:09:00 -0000	[thread overview]
Message-ID: <bug-51798-4-a9Gks9yyXg@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-51798-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51798

--- Comment #17 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-27 09:33:11 UTC ---
(In reply to comment #13)
> Any code that explicitly calls __sync_* in
> libstdc++-v3 has introduced a performance regression.

But if it happens in code that is executed only rarely (e.g. the EH code will
be dominated by time spent in the unwinder, not any barriers), then it might
not be even measurable.  So I think we should first change atomicity.h and only
if you can come up with a testcase which shows a significant regression for the
libsupc++ or parallel bits, we should change those too at this point.  We are
in stage4.


  parent reply	other threads:[~2012-01-27  9:33 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-09 14:31 [Bug libstdc++/51798] New: " dje at gcc dot gnu.org
2012-01-09 14:36 ` [Bug libstdc++/51798] " dje at gcc dot gnu.org
2012-01-09 14:38 ` dje at gcc dot gnu.org
2012-01-09 15:43 ` rguenth at gcc dot gnu.org
2012-01-09 17:12 ` dje at gcc dot gnu.org
2012-01-24  7:45 ` amacleod at redhat dot com
2012-01-24 16:46 ` dje at gcc dot gnu.org
2012-01-24 16:51 ` amacleod at redhat dot com
2012-01-25 14:27 ` jakub at gcc dot gnu.org
2012-01-25 15:39 ` dje at gcc dot gnu.org
2012-01-25 16:09 ` amacleod at redhat dot com
2012-01-25 16:17 ` dje at gcc dot gnu.org
2012-01-26 13:52 ` jakub at gcc dot gnu.org
2012-01-26 14:38 ` amacleod at redhat dot com
2012-01-26 15:50 ` dje at gcc dot gnu.org
2012-01-26 15:53 ` redi at gcc dot gnu.org
2012-01-26 21:50 ` dje at gcc dot gnu.org
2012-01-26 22:08 ` redi at gcc dot gnu.org
2012-01-27 10:09 ` jakub at gcc dot gnu.org [this message]
2012-01-27 11:37 ` jakub at gcc dot gnu.org
2012-01-27 13:03 ` amacleod at redhat dot com
2012-01-27 14:55 ` dje at gcc dot gnu.org
2012-01-27 15:01 ` jakub at gcc dot gnu.org
2012-01-27 15:26 ` dje at gcc dot gnu.org
2012-01-27 20:15 ` bkoz at gcc dot gnu.org
2012-01-27 21:05 ` jakub at gcc dot gnu.org
2012-01-27 21:08 ` jakub at gcc dot gnu.org
2012-02-09  8:46 ` bkoz at gcc dot gnu.org
2012-02-09  9:16 ` redi at gcc dot gnu.org
2012-02-09 20:08 ` bkoz at gcc dot gnu.org
2012-02-09 23:22 ` bkoz at gcc dot gnu.org
2012-02-10 18:21 ` bkoz at gcc dot gnu.org
2012-02-13 21:31 ` rth at gcc dot gnu.org
2012-02-17 21:03 ` bkoz at gcc dot gnu.org

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