Re: [patch] Real-Time Preemption, -RT-2.6.13-rc4-V0.7.52-01

[Daniel Walker <dwalker@mvista.com>]

On Tue, 2005-08-02 at 22:42 -0400, Steven Rostedt wrote:
> On Tue, 2005-08-02 at 19:25 -0700, Daniel Walker wrote:
> > On Tue, 2005-08-02 at 20:00 -0400, Steven Rostedt wrote:
> > > On Tue, 2005-08-02 at 16:38 -0700, Daniel Walker wrote:
> > > > Couldn't you just do some math off current->timestamp to see how long
> > > > the task has been running? This per arch stuff seems a bit invasive..
> > > 
> > > The thing is, I'm tracking how long the task is running in the kernel
> > > without doing a schedule.  That's actually easy, but I don't want to
> > 
> > Why make the distinction ? For what I was going for all I wanted to know
> > was that an RT task was eating up all the CPU . Did you have something
> > else in mind?
> 
> Yeah, bugs in the kernel :-)
> 
> I can change the patch to just see who is hogging the CPU for more than
> X amount of seconds (10 by default) if that pleases everyone. If that's
> what people want, then I'll send another patch tomorrow. If this is the
> way to go, then I'll add back the check for RT tasks to limit the output
> to just RT hogs.  Or is any hog OK?

The stack trace should show where the problem is . If it's in the kernel
we will see kernel functions before do_IRQ() , if it's just a whacked
out task then do_IRQ() would be first in the stack trace . 

I can't speak for everyone else, but I would want to catch both. That
way we'll know if it's just a whacked out task, or a kernel problem.

Daniel



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