Re: How to find long execution times in kernel threads?

Ashoka K
2013-05-01T03:58:12Z

Even i had some issues in schedule latencies. i tried to use trace-cmd
record -e all and kernelshark.
What i found was since it is run as a separate process it also need to
get scheduled to get the traces and by default it is get scheduled in
SCHED_OTHER. This tracing is also affected by the values in
/proc/sys/kernel/sched_rt_runtime_us and sched_rt_period_us.

So what i understood is for initial measurements kernelshark is a good
tool, but to go more deep this is not enough.
May be profiling tools like OPROF should be good. I am still exploring this.

Regards
Ashoka. K

On Tue, Apr 30, 2013 at 11:32 PM, Stanislav Meduna <stano@meduna.org> wrote:
> On 30.04.2013 18:52, Carsten Emde wrote:
>
>> Sure, record everything (trace-cmd record -e all) and analyze the
>> traces.
>
> Well, the problem is that with record -e all I get 20 ms instead
> of 1 ms, so I'd say Mr. Heisenberg laughs at me loudly here ;)
>
> Thanks for the pointer anyway, I'll try to thoroughly read
> the available documentation and come up with some sane set
> of filters to start with.
>
> Thanks
> --
> Stano
>
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