[ale] Which Distro should I use?

Chris Ricker kaboom at gatech.edu
Thu Jan 30 11:35:14 EST 2003


On Thu, 30 Jan 2003, Michael D. Hirsch wrote:

> On Thursday 30 January 2003 09:13 am, ChangingLINKS.com wrote:
> > 1. Is Gentoo "faster?"
> 
> Yes.  All packages get compiled for your specific hardware with as much 
> speed optimization as possible.  You will see more speed-ups on a p4 than 
> on a 486.

Does Gentoo or anybody else hyping the "compiled for your hardware" marketing
fluff actually have benchmarks showing speed increases? I'm curious b/c
I know both Caldera^WSCO and Red Hat have done internal tree builds optimized
for the exact CPU and found that in most cases it makes no difference.
Debian's currently in the process of rebuilding all of Sid compiled with
i686 optimization to see whether its worth doing, but it'll be a few weeks
before those results are available....

I'd be kinda surprised if it actually makes a difference for most packages;
gcc is fairly sucky at optimizing for specific chipsets....

> RH is compiled for a 486, so it doesn't take advantage of many 
> possible optimizations.

Wrong. Overall, Red Hat is compiled with i686 ordering optimization, but
using only i386+ compatible instructions. If you're familiar with gcc target
specification, Red Hat is compiled with:

gcc -mcpu=i686 -march=i386

so it runs optimally on i686, but still will execute on 386, 486, 586, K6-2,
Cyrix, Athlon, etc. cpus.

For a few packages where benchmarking shows a marked difference
(glibc, kernel, etc.), the Red Hat packages are compiled with both mcpu and
march set to specific machines (i686, athlon, i586, etc.) and the installer
and associated tools install the machine-specific version of the package.

Most other distros work similarly. I don't think anyone, other than
possibly Slackware, optimizes for i386 any more, and certainly no one ships
a 486-optimized distro.

later,
chris
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