FC3 and Pentium 4 optimization?
davej at redhat.com
Fri Jan 7 19:46:17 UTC 2005
On Fri, Jan 07, 2005 at 01:21:38PM -0600, Steve Bergman wrote:
> I am seeking clarification of a point made in the release notes. It
> states that FC3 is optimized for Pentium 4. However the kernels and
> glibc available are labeled as i686 and i386. I assume, since Pentium 1
> is the minimum hardware requirement, that the instruction set used is
> Pentium 1. So:
> 1. What optimization and instruction set are the general packages
> actually compiled with?
> 2. What optimization and instruction set are glibc-i686 and kernel-i686
> compiled with? (I seem to recall that the kernel is now optimized for size.)
> 3. How important is this to someone running a different processor? (Say
> Athlon XP.) IIRC p4 has very specific optimization requirements.
Currently, the kernel is compiled with -Os (size optimise),
with 686 instructions (so that it runs on early pentiums),
with instruction scheduling tuned for Pentium 4.
In tests I did, -mtune=pentium4 was a win on pretty much everything
I tried. Bizarrely in some cases, it even beat -mtune=athlon-xp
when I ran it on my athlon. VIA cpus didn't seem to be greatly
affected regardless of what the code was tuned for.
More information about the users