Re: [patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U4

From: Ingo Molnar
Date: Sat Oct 16 2004 - 14:40:14 EST



* Adam Heath <doogie@xxxxxxxxxx> wrote:

> > i have released the -U4 PREEMPT_REALTIME patch:
> >
> > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc4-mm1-U4
> >
> > this is a fixes-only release, and it is still experimental code.
>
> Few stack dumps now.

these are normal, they are the PREEMPT_TIMING traces which get printed
every time the kernel measures a new latency maximum. The stack dumps
are done to make it easier to identify which place too that long of a
delay and why. (if LATENCY_TRACE is enabled too then the last latency
and its trace can also be found in /proc/latency_trace.)

after bootup it makes sense to reset the maximum:

echo 10 > /proc/sys/kernel/preempt_max_latency

because during bootup there are a number of latencies that are one-time
only.

Ingo
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