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Re: Hunting for performance regressions in libstdc++
- From: Jonathan Wakely <cow at compsoc dot man dot ac dot uk>
- To: Dan Kegel <dank at kegel dot com>
- Cc: libstdc++ at gcc dot gnu dot org
- Date: Thu, 16 Jun 2005 12:53:45 +0100
- Subject: Re: Hunting for performance regressions in libstdc++
- References: <42B0FB92.7040506@kegel.com>
On Wed, Jun 15, 2005 at 09:09:54PM -0700, Dan Kegel wrote:
> I have a sneaking suspicion that some of my app's
> performance problems might be due to gcc-3.4.3's libstdc++
> being somehow slower than SGI's STL, so I'm planning
> on doing some performance testing of various implementations
> of STL.
You aren't, by any chance, using std::set::insert() with hints ?
We changed the behaviour of that function recently to conform to the
standard, which contradicts the traditional meaning of the hint. If
you are supplying a hint that points just before the insertion point
you will not get any speed-up.
jon
--
"The tools we use have a profound (and devious!) influence on our
thinking habits, and, therefore, on our thinking abilities."
- Edsger Dijkstra