Steven Rostedt wrote:

On Wed, 2 Jul 2008, Wolfgang Grandegger wrote:

quoted

Steven Rostedt wrote:

quoted

On Tue, 1 Jul 2008, Wolfgang Grandegger wrote:

quoted

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.