Re: Some very thought-provoking ideas about OS architecture.
Jeffrey B. Siegal (jbs@quiotix.com)
Tue, 22 Jun 1999 08:42:46 -0700
Jim Gettys wrote:
> More interesting may be Keith's recent results: while executing more
> instructions, but in a much more compact code base, he's seeing >10% kinds
> of speedups on the frame buffer coder (excluding text, where he's
> not worrying about speed; even so, dumb simple code is getting him
> 50K characters/second or more). Both the old code and the new code
> should be I/O bus cycle bound. Part of the speedup may be that he's
> able to use 64 bit constructs in the compiler, but part may be due to
> better instruction cache behavior.
Absolutely. In recent years, I have looked at the gross code expansion
done by the X server build (where some substantial code is compiled
multiple times, and in each case there is some pretty aggressive loop
unrolling) and thought that this might well be wrong given today's cache
issues. But I never did anything to test that theory. I'm glad to hear
that Keith has (as ever) been doing some good work in this area.
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