Re: Early hang with 2.6.21-rc4-rt1

Ingo Molnar
2007-03-30T09:24:41Z

* Ingo Molnar <mingo@elte.hu> wrote:

> > Great, thanks ... I'm not sure which of the 2 patches fixed things,
> > but I now got the following trace. I've not really analyzed this,
> > but it definitely looks like tun_init() is doing something fishy...
> > ("149776 us maximum-latency"!!)
>
> best would be to enable FUNCTION_TRACING and to do:
>
> echo 1 > /proc/sys/kernel/trace_enabled
> echo 1 > /proc/sys/kernel/mcount_enabled
>
> this will give you an exact trace of what happened, in
> /proc/latency_trace.

btw., if you use -rt, it makes sense to disable the UNWIND options in
the .config - the unwinder causes quite some overhead at places.

Ingo