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From: Robert Watson <rwatson@FreeBSD.org>
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Subject: Re: cvs commit: src/sys/i386/i386 pmap.c
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On Tue, 9 Nov 2004, Robert Watson wrote:

> > I've tried changing the store_rel() to just do a simple store since writes are 
> > ordered on x86, but benchmarks on SMP showed that it actually hurt.  However, 
> > it would probably be good to at least do that for UP.  The current patch to 
> > do it for all kernels is:

Interestingly, I've now run through some more "macro" benchmarks.  I saw a
couple of percent improvement on UP from the change, but indeed, I saw a
slight decrease in performance for the rapid packet send benchmark on SMP. 

So I guess my recommendation is to get this in the tree for UP, and see if
we can figure out why it's having the slow-down effect on SMP.

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