Date: Thu, 6 May 2004 22:55:46 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: 4.7 vs 5.2.1 SMP/UP bridging performance Message-ID: <Pine.NEB.3.96L.1040506225450.90990D-100000@fledge.watson.org> In-Reply-To: <200405061447.14406.jhb@FreeBSD.org>
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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
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