This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug libstdc++/51798] [4.7 regression] libstdc++ atomicity performance regression due to __sync_fetch_and_add
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 27 Jan 2012 09:33:11 +0000
- Subject: [Bug libstdc++/51798] [4.7 regression] libstdc++ atomicity performance regression due to __sync_fetch_and_add
- Auto-submitted: auto-generated
- References: <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.