Re: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch

From: Ingo Molnar
Date: Fri Jul 23 2004 - 00:48:53 EST

* Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:

> >this doesnt work either: once we've committed ourselves to do an
> >'immediate' softirq processing pass we are risking latencies. We cannot
> >preempt the idle task while it's processing softirqs the same way we can
> >do the lock-break if they are always deferred.
> >
> It is a preempt off region no matter where it is run. I don't see how
> moving it to ksoftirqd can shorten that time any further.

look at my latest patches to see how it's done. We can preempt softirq
handlers via lock-break methods. The same method doesnt work in the idle
thread. With this method i've reduced worst-case softirq latencies from
~2-4 msecs to 100-200 usecs on a 2GHz x86 box.

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