Re: 2.6.9-rc1-bk15-VP-R9 latency traces

From: Ingo Molnar
Date: Thu Sep 09 2004 - 12:12:00 EST



* William Stearns <wstearns@xxxxxxxxx> wrote:

> Good day, Ingo,
> Thanks for all your work on latency.
>
> I just rebooted my Dell Inspiron 8200 into 2.6.9-rc1-bk15-VP-R9
> (using your bk12-R9 patch on top of bk15). I got three latency traces
> during boot. I realize you're not as worried about those, but I thought
> I'd report them anyways.

the boot ones can be pretty bad at times and usually they are not a
worry: there's no user functionality during bootup so latencies have no
ill effects - the bootup itself is one huge 30-60 second latency to the
user!

If they happen during regular use too they are a problem. (not including
latencies that happen when suspending/resuming the laptop.)

> The above came from an untainted kernel. Please let me know if
> you need any more details. Thanks again for your work.

i'd suggest to reset the latency max via this line in
/etc/rc.d/rc.local:

echo 30 > /proc/sys/kernel/preempt_max_latency

this way you can delimit the boot-time ones from the ones that happen
later during normal use.

Ingo
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