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SubjectRe: Prerelease of 2.1.0


On Tue, 24 Sep 1996, Hans-Georg von Zezschwitz wrote:
>
> SMC Ultra is fine running 2.1.0

Thanks for the report..

> Another report about speed:
>
> Recompiling a clean pre2.1.0-tree with my configuration took:
>
> using Linux 2.0.21:
> 554.28user 36.98system 10:18.67elapsed 95%CPU (0avgtext+0avgdata
> 0maxresident)k
> 0inputs+0outputs (0major+0minor)pagefaults 0swaps
>
> using Linux 2.1.0:
> 553.11user 36.07system 10:15.06elapsed 95%CPU (0avgtext+0avgdata
> 0maxresident)k
> 0inputs+0outputs (0major+0minor)pagefaults 0swaps
>
> Well, that's 0,6%. Of cause, I can't claim that my single pass test
> has any relevance. Who Bever thinks, that this is very little, should
> consider that the German magazine c't was already delighted when
> Maple ran 10-15% faster using Linux instead of Windows.

Well, to be quite frank, I didn't expect all that much of a speed increase.
After all, the segment override stuff is generally just a few clock cycles,
and you end up spending more time just waiting for memory anyway (unless you
have a slow machine, and then you have a slow machine ;)

Also, I haven't actually gotten rid of the %fs stuff - I'll be able to shave
off a few ten clock cycles off the kernel entry routines by not having to
load %fs (and making "get_fs()"/"set_fs()" work like they do on the alpha).

But more important than the potential speed advantage (which is likely to
become more marked on newer CPU's) is the fact that I got rid of maintaining
a lot of inline assembly (look at <asm-i386/segment.h> before and after the
operation), and that the new setup works the same way on x86 (the bread and
butter of the Linux world) as on most other ports.

I'll try to produce better numbers (your differences are definitely within
the error limits),

Linus

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