Date: Mon, 28 Nov 2005 13:30:23 -0500
From: Dave Jones <davej@redhat.com>
To: Lee Revell <rlrevell@joe-job.com>
Cc: thockin@hockin.org, 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?
Message-ID: <20051128183023.GC30899@redhat.com>
Mail-Followup-To: Dave Jones <davej@redhat.com>,
	Lee Revell <rlrevell@joe-job.com>, thockin@hockin.org,
	Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
	john stultz <johnstul@us.ibm.com>,
	LKML <linux-kernel@vger.kernel.org>
References: <1133179554.11491.3.camel@localhost.localdomain> <20051128173040.GA32547@hockin.org> <1133199568.7416.31.camel@mindpipe>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1133199568.7416.31.camel@mindpipe>
User-Agent: Mutt/1.4.2.1i
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1018
Lines: 24

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...

Not true. Speedstep, or anything else that uses SMI to disappear
into magick bios code for long periods of time also have exactly
the same issue.

This is not a new problem.

		Dave

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/