Re: preemption and rwsems (was: Re: missing madvise functionality)

Ingo Molnar
2007-04-06T19:40:10Z

* Andrew Morton <akpm@linux-foundation.org> wrote:

> > i've attached an updated version of trace-it.c, which will turn this
> > off itself, using a sysctl. I also made WAKEUP_TIMING default-off.
>
> ok. http://userweb.kernel.org/~akpm/to-ingo.txt is the trace of
>
> taskset -c 0 ./jakubs-test-app
>
> while the system was doing the 150,000 context switches/sec.
>
> It isn't very interesting.

this shows an idle CPU#7: you should taskset -c 0 trace-it too - it only
traces the current CPU by default. (there's the
/proc/sys/kernel/trace_all_cpus flag to trace all cpus, but in this case
we really want the trace of CPU#0)

Ingo