i486 base architecture
Alan Cox
alan at redhat.com
Tue Nov 30 17:23:33 UTC 2004
On Tue, Nov 30, 2004 at 12:05:51PM -0500, William M. Quarles wrote:
> this case irrelevant instruction set), I'd really like to see that
> performance difference. Now were you saying that this cmov is part of
> i486 or i686? I'd like to try rebuilding everything to see if it makes
> a difference.
cmov is an optional instruction for i686 - it turns up on the PPro, PII, PIII,
PIV and Pentium M at least. By PIV its as slow or slower than not using it.
> Is the advantage still there, or is it just no longer a significant
> advantage? Or is it a cost? Unless it's a cost, I don't see what's
> wrong with putting in the advantage, unless it's a lot more work on your
> part. Is it more work?
Its a cost because some processors we support today lack this instruction but
are otherwise 686.
Alan
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