Date: Fri, 18 Apr 2008 12:35:23 +0930 From: "Daniel O'Connor" <doconnor@gsoft.com.au> To: freebsd-current@freebsd.org Cc: gnn@freebsd.org, Julian Elischer <julian@elischer.org>, Andrew Gallatin <gallatin@cs.duke.edu> Subject: Re: TSC Timecounter and multi-core/SMP Message-ID: <200804181235.29530.doconnor@gsoft.com.au> In-Reply-To: <48080276.3040203@elischer.org> References: <m2d4oy8n30.wl%gnn@neville-neil.com> <20080418003203.GB11705@dragon.NUXI.org> <48080276.3040203@elischer.org>
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On Fri, 18 Apr 2008, Julian Elischer wrote: > David O'Brien wrote: > > The TSC on K8 is not invariant - its rate of change is affected by > > P-state changes. > > > > The TSC on Greyhound (Family 10h) is invariant. > > [but as stated above, is not synced with other cores] > > You'd think that an invariant sync'd clock (fast to read) of some > type would have been done by someone by now.. The software people > have been asking for this for the last decade at least. Probably because it's very very difficult to get right :) -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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