Re: 2.6.24-rc8-rt1: Strange latencies on mpc5200 powerpc - RCU issue?

[Wolfgang Grandegger]

Steven Rostedt wrote:
> On Wed, 2 Jul 2008, Wolfgang Grandegger wrote:
>
> > Steven Rostedt wrote:
> > > On Tue, 1 Jul 2008, Wolfgang Grandegger wrote:
> > > > I continue this thread because it's still not understood why enabling
> > > > CONFIG_RCU_TRACE is necessary to get reasonable latencies on the
> > > > MPC5200. It might also explain, why I get much worse latencies with
> > > > 2.6.25.8-rt7.
> > > Have you tried turning on ftrace?
> > Hm, is it available for PowerPC? I have not found yet how to enable it.
>
> Hmm, should be. But I need to test it on my PPC box first before I can
> tell you for sure. If you don't see a way to enable it, perhaps I haven't
> updated the config options for PPC yet.

I added HAVE_FTRACE and HAVE_DYNAMIC_FTRACE to "config PPC" but more 
seems to be missing, e.g. arch/powerpc/kernel/ftrace.c. Nevertheless, 
how would I trigger high latency events with ftrace. I there a 
description somewhere?

Wolfgang.

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