|It's 1997. Do you know where your scheduler is? email@example.com (D. J. Bernstein) (1997-12-19)|
|Re: It's 1997. Do you know where your scheduler is? firstname.lastname@example.org (David Chase) (1997-12-23)|
|Re: It's 1997. Do you know where your scheduler is? email@example.com (D. J. Bernstein) (1997-12-29)|
|Re: It's 1997. Do you know where your scheduler is? firstname.lastname@example.org (David Greene) (1998-01-04)|
|From:||"D. J. Bernstein" <email@example.com>|
|Date:||29 Dec 1997 21:05:06 -0500|
> which release of gcc,
It really doesn't matter. Here are some Pentium cycle counts for the
same hand-scheduled 256-point complex FFT code:
23085 (best) gcc 126.96.36.199 -O1 -fo-f-p
41913 gcc 188.8.131.52 -O6 -fo-f-p
47258 egcs 1.00 -O6 -fo-f-p -mpentiumpro
56383 egcs 1.00 -O6 -fo-f-p -mpentium
56860 (worst) egcs 1.00 -O6 -fo-f-p
I wonder what percentage of today's typical Pentium is wasted by bad
instruction scheduling, given that so many programmers rely on the C
compiler for optimization. Intel's compiler is allegedly not too
incompetent, but how many programs are actually compiled with it?
> which release of Pentium.
``Pentium'' refers to a specific chip design. All Pentium releases
use the same number of cycles for in-cache operations.
The Pentium Pro, as you noted, is a very different chip. Scheduling
code badly for the Pentium Pro would take quite a bit of effort.
Apparently the Pentium MMX is similar to a Pentium for optimization
purposes, and the Pentium II is just like a Pentium Pro; except, of
course, for the extra instructions and larger L1 caches.
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