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From: Andi Kleen <ak@suse.de>
To: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>, Andrew Morton <akpm@osdl.org>,
	lkml <linux-kernel@vger.kernel.org>,
	discuss@x86-64.org
Subject: Re: [discuss] Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs
Date: Mon, 19 Sep 2005 21:49:34 +0200	[thread overview]
Message-ID: <20050919194934.GC12810@verdi.suse.de> (raw)
In-Reply-To: <1127158937.3455.214.camel@cog.beaverton.ibm.com>

On Mon, Sep 19, 2005 at 12:42:16PM -0700, john stultz wrote:
> On Mon, 2005-09-19 at 21:31 +0200, Andi Kleen wrote:
> > On Mon, Sep 19, 2005 at 12:16:43PM -0700, john stultz wrote:
> > > 	This patch should resolve the issue seen in bugme bug #5105, where it
> > > is assumed that dualcore x86_64 systems have synced TSCs. This is not
> > > the case, and alternate timesources should be used instead.
> > 
> > 
> > I asked AMD some time ago and they told me it was synchronized.
> > The TSC on K8 is C state invariant, but not P state invariant,
> > but P states always happen synchronized on dual cores.
> > 
> > So I'm not quite convinced of your explanation yet.
> 
> Would a litter userspace test checking the TSC synchronization maybe
> shed additional light on the issue?

Sure you can try it.

-Andi

  reply	other threads:[~2005-09-19 19:49 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-19 19:16 john stultz
2005-09-19 19:31 ` Andi Kleen
2005-09-19 19:42   ` john stultz
2005-09-19 19:49     ` Andi Kleen [this message]
2005-09-20 18:59       ` [discuss] " john stultz
2005-09-21  4:03         ` Daniel Jacobowitz
2005-09-21 15:15           ` Ray Bryant
2005-09-21 15:04             ` Andi Kleen
2005-09-21 15:46               ` Ray Bryant
2005-09-22  8:00                 ` Jonas Oreland
2005-09-21 20:17               ` Andrew Morton
2005-10-07 12:26 ` Vladimir B. Savkin
2005-10-07 12:31   ` Andi Kleen
2005-10-07 14:15     ` Vladimir B. Savkin
2005-10-07 14:21       ` [discuss] " Velu Erwan
2005-10-08 10:11     ` Vladimir B. Savkin
2005-10-10 18:03       ` john stultz
2005-10-10 18:12         ` Vladimir B. Savkin
2005-10-10 18:19           ` Jonas Oreland
2005-10-11  7:35             ` Vladimir B. Savkin
2005-10-11  8:06               ` Andi Kleen
2005-10-11 16:27               ` Jonas Oreland
2005-10-25  7:35                 ` x86-64: Syncing dualcore cpus TSCs Jonas Oreland
2005-10-25  7:42                   ` Andi Kleen
2005-10-26  0:05                     ` David Lang
2005-09-20 19:13 [discuss] Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs Langsdorf, Mark
2005-09-20 19:24 ` Scott Lampert
2005-09-20 19:30   ` john stultz

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