From: Lee Revell <rlrevell@joe-job.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
john stultz <johnstul@us.ibm.com>
Subject: Re: More weird latency trace output (was Re: 2.6.17-rt1)
Date: Sat, 24 Jun 2006 18:15:19 -0400 [thread overview]
Message-ID: <1151187320.2931.191.camel@mindpipe> (raw)
In-Reply-To: <1151025892.17952.32.camel@mindpipe>
On Thu, 2006-06-22 at 21:24 -0400, Lee Revell wrote:
> On Wed, 2006-06-21 at 22:51 -0400, Lee Revell wrote:
> > How can the latency tracer be reporting 1898us max latency while the
> > trace is of a 12us latency? This must be a bug, correct?
>
> I've found the bug. The latency tracer uses get_cycles() for
> timestamping, which uses rdtsc, which is unusable for timing on dual
> core AMD64 machines due to the well known "unsynced TSCs" hardware bug.
>
> Would a patch to convert the latency tracer to use gettimeofday() be
> acceptable?
OK, I tried that and it oopses on boot - presumably the latency tracer
runs before clocksource infrastructure is initialized.
Does anyone have any suggestions at all as to what a proper solution
would look like? Is no one interested in this problem?
Lee
next prev parent reply other threads:[~2006-06-24 22:15 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-18 7:06 2.6.17-rt1 Ingo Molnar
2006-06-18 16:13 ` 2.6.17-rt1 Michal Piotrowski
[not found] ` <Pine.LNX.4.64.0606201656230.11643@localhost.localdomain>
2006-06-20 15:13 ` Why can't I set the priority of softirq-hrt? (Re: 2.6.17-rt1) Thomas Gleixner
2006-06-20 17:09 ` Esben Nielsen
2006-06-20 16:35 ` Thomas Gleixner
2006-06-20 21:16 ` Esben Nielsen
2006-06-20 20:35 ` Thomas Gleixner
2006-06-20 23:19 ` Esben Nielsen
2006-06-20 16:39 ` Steven Rostedt
2006-06-20 18:12 ` Esben Nielsen
2006-06-20 17:21 ` Thomas Gleixner
2006-06-20 21:26 ` Esben Nielsen
2006-06-20 20:51 ` Thomas Gleixner
2006-06-21 8:20 ` Steven Rostedt
2006-06-21 11:05 ` Esben Nielsen
2006-06-21 15:43 ` Esben Nielsen
2006-06-21 15:21 ` Steven Rostedt
2006-06-21 16:37 ` Esben Nielsen
2006-06-21 15:51 ` Steven Rostedt
2006-06-21 17:14 ` Esben Nielsen
2006-06-21 16:26 ` Thomas Gleixner
2006-06-21 18:30 ` Ingo Molnar
2006-06-22 10:28 ` Esben Nielsen
2006-06-21 21:29 ` Esben Nielsen
2006-06-21 20:33 ` Thomas Gleixner
2006-06-21 23:35 ` Esben Nielsen
2006-06-22 7:06 ` Thomas Gleixner
2006-06-22 10:32 ` Esben Nielsen
2006-06-22 13:33 ` Steven Rostedt
2006-06-22 13:45 ` Steven Rostedt
2006-06-22 14:20 ` Thomas Gleixner
2006-06-22 14:23 ` Steven Rostedt
2006-06-22 14:26 ` Thomas Gleixner
2006-06-22 18:06 ` Esben Nielsen
2006-06-22 18:05 ` Thomas Gleixner
2006-06-23 11:23 ` Esben Nielsen
2006-06-23 11:06 ` Steven Rostedt
2006-07-03 11:48 ` Esben Nielsen
2006-06-21 8:13 ` Steven Rostedt
2006-06-21 11:03 ` Esben Nielsen
2006-06-22 0:57 ` 2.6.17-rt1 Lee Revell
2006-06-22 2:51 ` More weird latency trace output (was Re: 2.6.17-rt1) Lee Revell
2006-06-23 1:24 ` Lee Revell
2006-06-24 22:15 ` Lee Revell [this message]
2006-06-24 22:12 ` Ingo Molnar
2006-06-24 22:31 ` Lee Revell
2006-06-24 23:49 ` Lee Revell
2006-06-23 20:56 ` 2.6.17-rt1 - mm_struct leak Vernon Mauery
2006-06-24 9:24 ` Mark Hounschell
2006-06-24 9:32 ` Mark Hounschell
2006-06-30 16:02 ` [PATCH -RT]Re: " Vernon Mauery
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