Date: Mon, 14 Jun 2004 14:21:20 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: "David E. O'Brien" <obrien@FreeBSD.org> Subject: Re: cvs commit: src/sys/amd64/conf GENERIC Message-ID: <Pine.NEB.3.96L.1040614141907.34947B-100000@fledge.watson.org> In-Reply-To: <200406141418.16848.jhb@FreeBSD.org>
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On Mon, 14 Jun 2004, John Baldwin wrote: > On Sunday 13 June 2004 07:03 pm, David E. O'Brien wrote: > > obrien 2004-06-13 23:03:57 UTC > > > > FreeBSD src repository > > > > Modified files: > > sys/amd64/conf GENERIC > > Log: > > The majority of FreeBSD/amd64 machines are SMP, so use ADAPTIVE_MUTEXES > > by default to improve performance. > > We don't know if it improves performance yet. :) Yeah, as I was mentioning to David over the weekend, it's believed to help performance anecdotally in a number of interesting cases, and if we can show it helps in a majority of interesting cases (and doesn't substantially hurt the others) then I think this should actually be in GENERIC across all platforms, not just amd64. I also found I misunderstood his commit message as it seems to suggest it helps SMP at the cost of UP, but in fact does not say that. Kris reported that he experienced some apparent hangs related to running with ADAPTIVE_MUTEXES and we should resolve if it was actually the cause or whether it just triggered an existing race. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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