* Jörn Engel <joern@logfs.org> wrote:

quoted text
> > oprofile helps if you can reliably reproduce the slowdown in a loop 
> > or for a long amount of time, with lots of CPU utilization - and 
> > then it's also lower overhead. The tracer can be used to capture 
> > rare or complex events, and gives the full flow control and what is 
> > happening within the kernel.
> 
> Such a trace would be useful indeed.  But so far the patch has only 
> given me grief and nothing remotely like useful output.  Maybe I 
> should simply use the complete -rt patch instead of debugging the 
> broken-out latency-tracer patch.

to capture that trace i did not use -rt, i just patched latest -git 
with:

  http://people.redhat.com/mingo/latency-tracing-patches/latency-tracing-v2.6.24-rc3.com...

(this has your fixes included already)

have done:

  echo 1 > /proc/sys/kernel/mcount_enabled

and have run:

  ./trace-cmd sleep 1 > trace.txt

  http://people.redhat.com/mingo/latency-tracing-patches/trace-cmd.c

to capture a 1 second trace of what the system is doing. I think your 
troubles are due to running it within a qemu guest - that is not a 
typical utilization so you are on unchartered waters.

	Ingo
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