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compile time regressions (was: merging for 3.4)
- From: Gerald Pfeifer <pfeifer at dbai dot tuwien dot ac dot at>
- To: Matt Austern <austern at apple dot com>
- Cc: Eric Christopher <echristo at redhat dot com>, Neil Booth <neil at daikokuya dot co dot uk>, Jan Hubicka <hubicka at ucw dot cz>, Joe Buck <jbuck at synopsys dot com>, Diego Novillo <dnovillo at redhat dot com>, Mark Mitchell <mark at codesourcery dot com>, Benjamin Kosnik <bkoz at redhat dot com>, Gabriel Dos Reis <gdr at integrable-solutions dot net>, "pcarlini at unitus dot it" <pcarlini at unitus dot it>, "libstdc++ at gcc dot gnu dot org" <libstdc++ at gcc dot gnu dot org>, "" <gcc at gcc dot gnu dot org>
- Date: Thu, 5 Dec 2002 21:39:15 +0100 (CET)
- Subject: compile time regressions (was: merging for 3.4)
- References: <F65E3CFB-07D4-11D7-A567-00039390D9E0@apple.com>
On Wed, 4 Dec 2002, Matt Austern wrote:
> Are there good test cases for the 3.1 -> 3.3 compile time
> regressions? It would be interesting to study them and find out
> just what has gotten slower.
PR 3083 (yes, that old) basically still applies, but has been superseded
by PR 8361 (http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=8361).
> If the numbers people have been tossing around are real then these are
> very serious regressions and we should consider slipping the schedule
> rather than releasing a compiler with those sorts of performance
> problems.
Here are some timings from that PR:
gcc-3.0.4/bin/g++ 45.45 user
gcc-3.1.1/bin/g++ 57.79 user +27%
gcc-3.2.1/bin/g++ 59.30 user +30%
gcc-current/bin/g++ 72.29 user +59%
Devang asked me wrt. to number w/o optimization:
On Fri, 25 Oct 2002, Devang Patel wrote:
> Is it possible to get numbers for compilations without optimization?
Now, that's quite interesting:
/sw/gcc-3.0.4/bin/g++
25.60 real 24.66 user 0.63 sys
/sw/gcc-3.1.1/bin/g++
28.44 real 26.88 user 0.98 sys
/sw/gcc-3.2.1/bin/g++
28.71 real 27.17 user 0.65 sys
/sw/gcc-current/bin/g++
32.14 real 31.06 user 0.59 sys
That is, we are already quite bad (and regress) without optimization.
Gerald
--
Gerald "Jerry" pfeifer@dbai.tuwien.ac.at http://www.pfeifer.com/gerald/