Re: [BUG] Strange 1-second pauses during Resume-from-RAM

Ingo Molnar
2007-12-02T20:46:30Z

* Jörn Engel <joern@logfs.org> wrote:

> > 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.combo.patch

(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