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

Steven Rostedt
2005-08-03T10:35:52Z

On Tue, 2005-08-02 at 19:58 -0700, Daniel Walker wrote:
> 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 .

The problem is not differentiating tho output as kernel or user, I just
don't want too many false positives.

>
> 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.

The thing is, it may be OK for a RT process to run in userspace for 10
seconds without sleeping. If this is the case, you will constantly get
this output saying you may mave a bug. But if the kernel is running for
10 seconds without scheduling, I strongly believe that is a bug. Unless
someone has some special driver thread, I don't know of any kernel path
that runs for 10 seconds without going back to userspace or sleeping.

I still wish there was a nice arch-independent way to tell if the task
is running in user space from do_IRQ. Maybe there is? I'll post
another thread and ask the question.

-- Steve