From: thockin@hockin.org
To: Lee Revell <rlrevell@joe-job.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
john stultz <johnstul@us.ibm.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RT] read_tsc: ACK! TSC went backward! Unsynced TSCs?
Date: Mon, 28 Nov 2005 10:35:17 -0800 [thread overview]
Message-ID: <20051128183517.GA4549@hockin.org> (raw)
In-Reply-To: <1133199568.7416.31.camel@mindpipe>
On Mon, Nov 28, 2005 at 12:39:28PM -0500, Lee Revell wrote:
> On Mon, 2005-11-28 at 09:30 -0800, thockin@hockin.org wrote:
> > The kernel's use of TSC is wholly incorrect. TSCs can ramp up and
> > down and *do* vary between nodes as well as between cores within a
> > node. You really can not compare TSCs between cpu cores at all, as is
> > (and the kernel assumes 1 global TSC in at least a few places).
>
> That's one way to look at it; another is that the AMD dual cores have a
> broken TSC implementation. The kernel's use of the TSC was never a
> problem in the past...
Sure. But the OS can be fixed, the chips can not. That said, I'd like to
see a spec that says TSCs are a) synced, b) linear. If such a beast
exists, then we can all mock AMD publicly. If not, we should hush up and
fix the parts that can be fixed.
next prev parent reply other threads:[~2005-11-28 18:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-28 12:05 [RT] read_tsc: ACK! TSC went backward! Unsynced TSCs? Steven Rostedt
2005-11-28 12:30 ` Jonas Oreland
2005-11-28 12:59 ` Steven Rostedt
2005-11-28 14:21 ` Ingo Molnar
2005-11-28 15:38 ` Lee Revell
2005-11-28 17:30 ` thockin
2005-11-28 17:39 ` Lee Revell
2005-11-28 18:30 ` Dave Jones
2005-11-28 18:35 ` thockin [this message]
2005-11-29 14:06 ` Andi Kleen
2005-11-29 16:52 ` thockin
2005-11-29 16:48 ` Andi Kleen
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