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From: john stultz <johnstul@us.ibm.com>
To: Scott Lampert <scott@lampert.org>
Cc: "Langsdorf, Mark" <mark.langsdorf@amd.com>,
	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: Tue, 20 Sep 2005 12:30:56 -0700	[thread overview]
Message-ID: <1127244656.11080.24.camel@cog.beaverton.ibm.com> (raw)
In-Reply-To: <433061E4.20903@lampert.org>

On Tue, 2005-09-20 at 12:24 -0700, Scott Lampert wrote:
> Langsdorf, Mark wrote:
> >>Personally I suspect that the powernow driver is putting the 
> >>cores independently into low power sleep and the TSCs are 
> >>being independently halted, causing them to become unsynchronized.
> >
> >The powernow-k8 driver doesn't know what a low power sleep state
> >is, so I strongly doubt it is involved here.  It only handles
> >pstates.
> > 
> Just to add some end-user input here, I see the same issues regardless 
> of whether I'm running with the powernow-k8 or not.  The clock problems 
> seem to be unrelated to that, at least on my system.

Hmmm. Ok, I don't know the cpufreq/power management code well enough. 

I know some Intel cpus halt the TSC in C3. Could the ACPI code be
causing this? 

Could anyone with better knowledge speak to why it looks like the TSCs
are unsynced? Is my test flawed?

thanks
-john



  reply	other threads:[~2005-09-20 19:31 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-20 19:13 Langsdorf, Mark
2005-09-20 19:24 ` Scott Lampert
2005-09-20 19:30   ` john stultz [this message]
  -- strict thread matches above, loose matches on Subject: below --
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     ` [discuss] " Andi Kleen
2005-09-20 18:59       ` 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

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