Messages in this thread |  | | Date | Fri, 29 Oct 2004 22:30:31 +0200 | | From | Ingo Molnar <> | | Subject | Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.5.2 |
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* John Gilbert <jgilbert@biomail.ucsd.edu> wrote:
> Hello all, Ingo, > Here's a few bugs on boot with V0.5.2, and a question: what's needed to > get back to the verbose latency messages of previous preempt patches > (see the terse second log)?
> (ksoftirqd/0/2/CPU#0): new 1003 us maximum-latency wakeup.
if you have LATENCY_TRACING enabled then the wakeup trace of the last wakeup will be in /proc/latency_trace.
the reason that the messages are less verbose is that by default we are not measuring critical sections anymore, but 'wakeup latency'. Wakeup latency is measured from the point of wakeup to the point where the task runs - so it makes no sense to dump the stack (which is why the previous tracing output was more verbose) - a stackdump would always show the scheduler codepath where we stop measuring.
you can switch back to critical section timing though, via:
echo 0 > /proc/sys/kernel/preempt_wakeup_timing
this will also turn the stackdumps back on. (those make sense in this case because we measure 'start of critical section' to 'end of critical section', in which case both a stackdump and the symbolic printout of the start and end address is useful - because it's variable.
Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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