From: William Lee Irwin III <wli@holomorphy.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <andi@firstfloor.org>,
Satyam Sharma <satyam.sharma@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [patch] i386, numaq: enable TSCs again
Date: Fri, 25 May 2007 01:19:44 -0700 [thread overview]
Message-ID: <20070525081944.GZ31925@holomorphy.com> (raw)
In-Reply-To: <20070525080827.GA22399@elte.hu>
On Fri, May 25, 2007 at 10:08:27AM +0200, Ingo Molnar wrote:
> Andi, Andrew, do you remember why we disabled TSCs on NUMAQ? It was
> slightly async between CPUs, right? In that case we should try the patch
> below.
I remember. It was far beyond "slightly async;" they would drift
minutes apart during reasonable amounts of uptime, though it would take
at least several days to drift so far (I don't recall how long it took).
TSC synchronization is uniformly impossible on NUMA-Q. Bootlogs showing
the results of the attempts are still extant. They shouldn't end up too
far apart right after booting, but I don't have even ballpark estimates.
I'd hazard a guess of a few seconds.
NUMA-Q's also supported mixed CPU models in hardware, though that's
not really expected to be handled by Linux. I suspect DYNIX/ptx would
be used by anyone interested in that.
-- wli
next prev parent reply other threads:[~2007-05-25 8:19 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-25 7:10 [patch] sched_clock(): cleanups Ingo Molnar
2007-05-25 7:22 ` Satyam Sharma
2007-05-25 7:25 ` Ingo Molnar
2007-05-25 7:26 ` Ingo Molnar
2007-05-25 7:35 ` Satyam Sharma
2007-05-25 7:39 ` Peter Zijlstra
2007-05-25 7:58 ` Andi Kleen
2007-05-25 8:02 ` Ingo Molnar
2007-05-25 8:16 ` Peter Zijlstra
2007-05-25 8:21 ` Andi Kleen
2007-05-25 7:38 ` Andi Kleen
2007-05-25 7:31 ` Andi Kleen
2007-05-25 7:39 ` Ingo Molnar
2007-05-25 7:43 ` Ingo Molnar
2007-05-25 7:49 ` Ingo Molnar
2007-05-25 7:54 ` [patch] x86_64: fix sched_clock() Ingo Molnar
2007-05-25 8:02 ` Andi Kleen
2007-05-25 8:04 ` Ingo Molnar
2007-05-25 8:20 ` Andi Kleen
2007-05-25 8:34 ` Ingo Molnar
2007-05-25 8:41 ` Andi Kleen
2007-05-25 8:44 ` Ingo Molnar
2007-05-25 8:45 ` Andi Kleen
2007-05-25 8:55 ` Ingo Molnar
2007-05-25 8:55 ` Andrew Morton
2007-05-25 9:03 ` Andi Kleen
2007-05-25 9:19 ` Ingo Molnar
2007-05-25 9:46 ` Andi Kleen
2007-05-25 10:12 ` Ingo Molnar
2007-05-25 11:20 ` Andi Kleen
2007-05-25 11:26 ` Ingo Molnar
2007-05-25 11:31 ` Ingo Molnar
2007-05-25 11:46 ` [patch] sched_clock: fix preempt count imbalance Ingo Molnar
2007-05-25 11:50 ` [patch] sched_clock(): cleanups, #2 Ingo Molnar
2007-05-25 11:55 ` Andi Kleen
2007-05-25 12:02 ` Ingo Molnar
2007-05-25 12:15 ` Andi Kleen
2007-05-25 16:17 ` Andrew Morton
2007-05-25 16:26 ` Daniel Walker
2007-05-25 16:33 ` Andi Kleen
2007-05-25 16:49 ` Linus Torvalds
2007-05-25 18:08 ` Andi Kleen
2007-05-25 19:14 ` Ingo Molnar
2007-05-25 19:45 ` Linus Torvalds
2007-05-25 10:27 ` [patch] x86_64: fix sched_clock() Ingo Molnar
2007-05-25 11:05 ` Andi Kleen
2007-05-28 3:12 ` Rusty Russell
2007-05-25 8:08 ` [patch] i386, numaq: enable TSCs again Ingo Molnar
2007-05-25 8:19 ` William Lee Irwin III [this message]
2007-05-25 8:22 ` Andi Kleen
2007-05-25 8:25 ` William Lee Irwin III
2007-05-25 8:31 ` Ingo Molnar
2007-05-25 8:38 ` William Lee Irwin III
2007-05-25 8:41 ` Ingo Molnar
2007-05-25 18:16 ` Dave Hansen
2007-05-25 18:23 ` john stultz
2007-05-25 8:15 ` [patch] x86_64: fix sched_clock() Peter Zijlstra
2007-05-25 8:16 ` Ingo Molnar
2007-05-25 8:22 ` [patch] sched_clock(): cleanups Peter Zijlstra
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