Re: Upcoming Debian multiarch support (amd64, sparc64, s390x, mips64) [affects sarge slightly]

[Colin Watson <cjwatson@debian.org>]

On Tue, Jan 13, 2004 at 09:25:31AM +0100, Goswin von Brederlow wrote:
> Colin Watson <cjwatson@debian.org> writes:
> > It's not necessarily that simple; many applications are disk-bound
> > anyway, and furthermore in 64-bit mode you spend more time shuffling
> > pointers around. When I was doing benchmarking work on the Opteron at
> > AMD early last year (albeit on web servers, so perhaps not a good
> > analogy for desktops), it was becoming clear to me that having the
> > flexibility of 32-bit mode for some applications and 64-bit for others
> > was useful, and the results of some of those benchmarks were slightly in
> > favour of 32-bit mode.
> > 
> > I haven't touched an Opteron for nearly a year now, though ...
> 
> I think in the end a pure 64 bit system would win that last bit of
> speed because less code needs to be cached.

You're probably right there.

> Running a 32bit biary might be faster than the 64bit flavour but it
> might slow down all the other 64bit apps.

I'm not sure how ...? Presumably you have lots of memory so the extra
copy of libc in RAM isn't going to be a problem.

> As with all benchmarks the truth lies in the eye of the testcase
> creator. I'm sure you can make a perfectly reproducible and meaning
> full test either way.

Amen. :-) (I don't do benchmarks any more, for which I am truly
thankful.)

-- 
Colin Watson                                  [cjwatson@flatline.org.uk]