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Re: GCC 4.1: Buildable on GHz machines only?
- From: "H. J. Lu" <hjl at lucon dot org>
- To: Andrew Haley <aph at redhat dot com>
- Cc: Joe Buck <Joe dot Buck at synopsys dot COM>,Alexandre Oliva <aoliva at redhat dot com>,David Edelsohn <dje at watson dot ibm dot com>, Andreas Schwab <schwab at suse dot de>,Richard Earnshaw <rearnsha at gcc dot gnu dot org>,Andrew Pinski <pinskia at physics dot uc dot edu>,Paul Koning <pkoning at equallogic dot com>, s dot bosscher at student dot tudelft dot nl,gcc at gcc dot gnu dot org, matt at 3am-software dot com, cow at compsoc dot man dot ac dot uk
- Date: Wed, 4 May 2005 06:41:59 -0700
- Subject: Re: GCC 4.1: Buildable on GHz machines only?
- References: <1114694844.2729.240.camel@pc960.cambridge.arm.com> <17008.59023.361787.925505@cuddles.cambridge.redhat.com> <jebr7z80nt.fsf@sykes.suse.de> <17009.2368.986169.753001@cuddles.cambridge.redhat.com> <200504281609.j3SG9ZD27524@makai.watson.ibm.com> <20050428164727.GB30649@synopsys.com> <200504281654.j3SGs0D27158@makai.watson.ibm.com> <oracncw0a1.fsf@livre.redhat.lsd.ic.unicamp.br> <20050503220342.GA23969@synopsys.com> <17016.41624.799846.161219@cuddles.cambridge.redhat.com>
On Wed, May 04, 2005 at 11:23:20AM +0100, Andrew Haley wrote:
> Joe Buck writes:
> > On Tue, May 03, 2005 at 04:57:10PM -0300, Alexandre Oliva wrote:
> > > At this point, it doesn't feel like switching to 1.5.16 is worth the
> > > effort. 2.0 should be far more maintainable, and hopefully
> > > significantly more efficient on hosts where the use of shell functions
> > > optimized for properties of the build machine and/or the host
> > > machine can bring us such improvement.
> >
> > > Thoughts?
> >
> > Richard Henderson showed that the libjava build spends 2/3 of its time
> > in libtool, and that his hand-hacked (but not portable) modification to
> > invoke the appropriate binutils commands directly gave a huge speedup.
>
> Yes, but please bear in mind that this *only* happens when you have a
> machine with huge RAM. For other people with small RAM, the link
> itself is an important factor. Also, other people have found that the
> libtool script consumes a smaller part of total execution time: rth's
> measurements are at one extreme of the scale.
>
We have been working on linker speed. If you have a number to show
that the GNU linker is very slow on certain things, I will take a
look.
H.J.