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Message-Id: <1254333456.2194.27.camel@frodo> Date: Wed, 30 Sep 2009 13:57:36 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: Dick Hollenbeck <dick@...tplc.com> Cc: linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org> Subject: Re: 2.6.31.1 boot crash, compiled with ftrace 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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