From: Steven Rostedt <rostedt@goodmis.org>
To: Dick Hollenbeck <dick@softplc.com>
Cc: linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>
Subject: Re: 2.6.31.1 boot crash, compiled with ftrace
Date: Wed, 30 Sep 2009 13:57:36 -0400 [thread overview]
Message-ID: <1254333456.2194.27.camel@frodo> (raw)
In-Reply-To: <4AC371C6.3050104@softplc.com>
On Wed, 2009-09-30 at 09:57 -0500, Dick Hollenbeck wrote:
> My real pursuit here is to find the reason for a nearly 1 second latency
> when running a SCHED_RR userspace process. The filesystem is ext3 off
> the flash card via IDE. Linux is yanking the machine away from this
> process sporadically for up to 1 second, no disk file calls in this
> proces, only some serial port and networking (epoll) userspace calls in
> a loop. It is insane. So I have to get either LTT or FTRACE enabled,
> never used either before. Its been a tough 2 weeks. Just getting the
> LTT patches in sync with a decent kernel has been nearly unbearable.
>
Great to hear that you narrowed it down. BTW, if you want to learn some
more about ftrace, I just gave a 2 hour tutorial at LinuxCon last week.
You can download the slides in the link below. They show lots of
samples. I'll also start writing a howto for LWN real soon. So if you
don't already have a subscription, I suggest you get one ;-)
http://people.redhat.com/srostedt/ftrace-tutorial-linux-con-2009.odp
-- Steve
prev parent reply other threads:[~2009-09-30 17:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-29 15:21 2.6.31.1 boot crash, compiled with ftrace Dick Hollenbeck
2009-09-30 8:03 ` Steven Rostedt
2009-09-30 9:09 ` Steven Rostedt
2009-09-30 14:57 ` Dick Hollenbeck
2009-09-30 17:57 ` Steven Rostedt [this message]
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