Re: compiling linux kernels with GCC 3.0

["Tim Prince" <tprince@computer.org>]

The partial register stalls, blocked store forwarding, et al,
penalize the P4 much more severely than the AMD processors.
Honza has corrected several of these problems in gcc-3.1, so,
although 3.0.x perform much worse than 2.95.x, performance is
more than recovered in 3.1.  I've found a few popular public
benchmarks where gcc-3.1/g77 beats all of the commercial
compilers on p4, when appropriate compiler options are chosen; of
course there are more where that is not so.  AMD may be paying
more than their share of the bill for the improvements in gcc,
but the developers have not failed to make improvements which
have more benefit for Intel processors than for AMD.
----- Original Message -----
From: "Paolo Carlini" <pcarlini@unitus.it>
To: "Richard Henderson" <rth@redhat.com>
Cc: <gcc@gcc.gnu.org>
Sent: Wednesday, October 10, 2001 5:09 PM
Subject: Re: compiling linux kernels with GCC 3.0


> Richard Henderson wrote:
>
> > >     http://gcc.gnu.org/ml/gcc/2001-09/msg00217.html
> >
> > This is actually a new bug.  It very much post-dates the
> > back end rewrite.
>
> Sure, between 3.0 and 3.0.1.
>
> However, I'm still wondering if perhaps such kind of specific
problems my
> slightly penalize Intel processors with respect to AMD ones in
both absolute and
> relative terms (Joe Buck argued for a progress from 2.95.3 to
3.0 to 3.0.1 on
> AMD). What do you believe?
>
> Thanks for introducing me to partial register stall issues!!
> Paolo Carlini.
>