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Date: Thu, 6 May 2004 22:55:46 -0400 (EDT)
From: Robert Watson <rwatson@FreeBSD.org>
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Subject: Re: 4.7 vs 5.2.1 SMP/UP bridging performance
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On Thu, 6 May 2004, John Baldwin wrote:

> > According to http://www.sandpile.org/ia32/coherent.htm,
> > both mfence and lfence require SSE2, so sfence has the broadest
> > coverage.
> >
> > But since only P4 needs it, and since lfence is ~25% cheaper, maybe
> > there should be a separate config option for it, and it should be a
> > straight conditional compile option for those of us cursed w/P4s.
> 
> That could work I guess.  Just can't stick it in GENERIC.
> 
> options	INTEL_MADE_MY_PIV_A_TORTOISE
> 
> or some such. :)

On occasion, I've had conversations with Peter Wemm about providing HAL
modules with optimized versions of various common routines for specific
hardware platforms.  However, that would require us to make a trade-off
between the performance benefits of inlining and the performance benefits
of a HAL module...

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Senior Research Scientist, McAfee Research