Date: Tue, 15 Apr 2008 21:43:04 -0700 From: "Peter Wemm" <peter@wemm.org> To: "David Malone" <dwmalone@maths.tcd.ie> Cc: gnn@freebsd.org, Jeff Roberson <jroberson@jroberson.net>, Andrew Gallatin <gallatin@cs.duke.edu>, current@freebsd.org Subject: Re: TSC Timecounter and multi-core/SMP Message-ID: <e7db6d980804152143x4dcd17efn15bd37632ec42108@mail.gmail.com> In-Reply-To: <20080415084602.GA44129@walton.maths.tcd.ie> References: <m2d4oy8n30.wl%gnn@neville-neil.com> <18431.23276.913397.188219@grasshopper.cs.duke.edu> <m27iezwonx.wl%gnn@neville-neil.com> <20080414215057.B959@desktop> <20080415084602.GA44129@walton.maths.tcd.ie>
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On Tue, Apr 15, 2008 at 1:46 AM, David Malone <dwmalone@maths.tcd.ie> wrote: > On Mon, Apr 14, 2008 at 09:51:42PM -1000, Jeff Roberson wrote: > > I think we should confirm whether this is the case with earlier opterson. > > I have seen two processors on the same die out of sync. > > This can definitely happen according to this note from AMD, which > someone posted a link to earlier in the thread: > > > http://lkml.org/lkml/2005/11/4/173 > > it can happen when you hlt one core, but don't hlt the other on > some processors. AMD even ship a special program / driver / hack / whatever that synchronizes the TSC on multi-core systems. The Athlon64 X2 that I have at home for games needs it for older programs to run correctly. I'm not in front of it right now, but I think it is called 'dual core cpu optimizer' or something vague like that. -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5 "If Java had true garbage collection, most programs would delete themselves upon execution." -- Robert Sewell
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