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Re: serious (5x) link-time regression in 3.3.5-12 on ia64


How about collecting some profiles (e.g., with qprof or q-syscollect)?
That might be a quick way to get some idea as to what's causing the


>>>>> On Sun, 3 Apr 2005 16:04:48 +0200, Matthias Klose <doko@cs.tu-berlin.de> said:

  Matthias> according to the changelog, nothing really has changed
  Matthias> ... CCing to the ia64 list.

  Matthias> Duraid Madina writes:
  >> Hi Mathias, Gerhard and others,
  >> I want to report a nasty performance regression in
  >> 3.3.5-12. Moving from:
  >> gcc version 3.3.5 (Debian 1:3.3.5-11)
  >> to:
  >> gcc version 3.3.5 (Debian 1:3.3.5-12)
  >> leads to a large reduction in C++ software build speeds, due to
  >> something that apparently makes 'ld' spend much, much more time
  >> than it previously did. I reproduced this problem going backwards
  >> and forwards between these versions by commands like:
  >> dpkg -i g++-3.3_3.3.5-11_ia64.deb gcc-3.3-base_3.3.5-11_ia64.deb
  >> gcc-3.3_3.3.5-11_ia64.deb
  >> so, as far as I understand, neither libstdc++ nor binutils
  >> changed.
  >> How bad is the problem? Trying to build the LLVM compiler suite,
  >> (say, version 1.4 from http://llvm.cs.uiuc.edu/releases/ ) on a
  >> 2-way IA64 system with a simple ./configure; time make -j2 with
  >> gcc 3.3.5-11 gives:
  >> real 1048.03 user 1979.93 sys 54.37
  >> but with gcc 3.3.5-12 gives:
  >> real 1641.14 user 3037.64 sys 49.62
  >> Nasty! The build takes 60% longer with 3.3.5-12, and while I
  >> haven't timed it accurately, the time spent in linking has
  >> _greatly_ increased, by a factor of at least 5x, perhaps
  >> 10x. LLVM is fairly "normal" and portable C++, though it is a
  >> large source base. (not quite mozilla-sized, though)
  >> Unfortunately, build times from (gcc version 3.4.4 20050314
  >> (prerelease) (Debian 3.4.3-12)) are more or less the same as
  >> those of 3.3.5-12, i.e. slow. Again, components of LLVM take
  >> literally minutes to link on a rather snappy Itanium system. I
  >> have not tested older versions of 3.4 to see if these too have
  >> the performance regression from 3.3.5-11.
  >> I would appreciate it if you could bring this to the attention of
  >> the relevant people, and I hope I'm posting this in the right
  >> place! If anyone wants an even more painless way of reproducing
  >> this problem, please contact me and I will provide a tarball that
  >> you can simply unpack, configure, make. I'd also appreciate it if
  >> someone could confirm exactly what has changed between the
  >> 3.3.5-11 and 3.3.5-12 packages of gcc, gcc-base and g++. diffing
  >> gcc-3.3_3.3.5-11.diff and gcc-3.3_3.3.5-12.diff, I can't see
  >> anything obviously responsible for this regression, so I wonder
  >> if perhaps some sort of changed environment on whatever machine
  >> built gcc-3.3.5-12 might be responsible for this regression.
  >> Finally, note that this is all on ia64. I imagine it is likely
  >> that this regression is platform specific, but the only Debian
  >> systems I have ready access to are ia64 ones, so I can't test
  >> this.
  >> Many thanks in advance,
  >> Duraid
  >> -- 
  >> To UNSUBSCRIBE, email to debian-gcc-REQUEST@lists.debian.org with
  >> a subject of "unsubscribe". Trouble? Contact
  >> listmaster@lists.debian.org

  Matthias> -- To UNSUBSCRIBE, email to
  Matthias> debian-ia64-REQUEST@lists.debian.org with a subject of
  Matthias> "unsubscribe". Trouble? Contact
  Matthias> listmaster@lists.debian.org

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