Re: Latency data - 2.6.14-rc3-rt13
From: Ingo Molnar
Date: Tue Oct 11 2005 - 06:17:03 EST
* Mark Knecht <markknecht@xxxxxxxxx> wrote:
> > ( softirq-timer/0-3 |#0): new 3997 us maximum-latency critical section.
> So the root cause of this 4mS delay is the 250Hz timer. If I change
> the system to use the 1Khz timer then the time in this section drops,
> as expected, to 1mS.
this was a bug in the critical-section-latency measurement code of x64.
The timer irq is the one that leaves userspace running for the longest
time, between two kernel calls.
I have fixed these bugs in -rc4-rt1, could you try it? It should report
much lower latencies, regardless of PM settings.
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