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Re: CPU specific/optimized Debian builds ?



On Wed, May 29, 2002 at 09:48:33AM +0200, Ulrich Eckhardt wrote:
> On Wednesday 29 May 2002 01:30, Adam Heath wrote:
> > On Wed, 29 May 2002, Ulrich Eckhardt wrote:
> > >
> > > Debian's debs:
> > > around 3.6 seconds
> > >
> > > compiled bzip2 and tar with DEBIAN_BUILDARCH=k6:
> > > around 3.5 seconds
> >
> > Noise.
> No. Marginal but visible.

No, it really is noise. At the accuracy you have given (one decimal
place), a change of 0.1 is statistically meaningless, especially since
you said "about". It can easily be attributed to aliasing effects (a
0.0001 shift about the 3.55 mark will result in a shift from 3.5 to
3.6).

The figures you have given here are not meaningful.

> > > compiled with DEBIAN_BUILDARCH=k6 and GCCVER=3.0
> > > around 3.3 seconds
> > >
> > > compiled with DEBIAN_BUILDARCH=athlon and GCCVER=3.0
> > > around 3.3 seconds
> >
> > No change for k6/athlon.  However, it appears that GCC=3.0 gives very good
> > numbers.
> >
> > What happens if you compile with just 3.0, but no BUILDARCH?
> >
> > Also, use a biggest test case.  This one is rather small.
> 
> Hmmm, everyone can do so on their own machines easily .... how are the 
> results on yours ? :)
> 
> I'll give it a more systematic try with a linux-kernel sourcetree instead of 
> my cvsroot, but that's later today.

That is not a deterministic test. It doesn't provide a particularly
useful benchmark; it involves a semi-random pattern of disk access
which is hopelessly skewed by environmental factors.

If you are trying to do a benchmark on processor-related performance
changes (which it seems like you are), you will have to construct a
benchmark which actually measures that (no, I don't have any
suggestions offhand).

-- 
  .''`.  ** Debian GNU/Linux ** | Andrew Suffield
 : :' :  http://www.debian.org/ | Dept. of Computing,
 `. `'                          | Imperial College,
   `-             -><-          | London, UK


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