Re: 2.6.31.1 boot crash, compiled with ftrace

[Steven Rostedt]

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


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