Re: [Bug #12465] KVM guests stalling on 2.6.28 (bisected)

Steven Rostedt
2009-01-20T14:59:01Z

On Tue, 20 Jan 2009, Ingo Molnar wrote:
> Another test would be to build the scheduler latency tracer into your
> kernel:
>
> CONFIG_SCHED_TRACER=y
>
> And enable it via:
>
> echo wakeup > /debug/tracing/current_tracer
>
> and you should be seeing the worst-case scheduling latency traces in
> /debug/tracing/trace, and the largest observed latency will be in
> /debug/tracing/tracing_max_latency [in microseconds].

Note, the wakeup latency only tests realtime threads, since other threads
can have other issues for wakeup. I could change the wakeup tracer as
wakeup_rt, and make a new "wakeup" that tests all threads, but it may
be difficult to get something accurate.

-- Steve