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Date: Fri, 23 Jul 2004 07:47:35 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Lee Revell <rlrevell@joe-job.com>, Andrew Morton <akpm@osdl.org>,
       linux-audio-dev@music.columbia.edu, arjanv@redhat.com,
       linux-kernel <linux-kernel@vger.kernel.org>,
       "La Monte H.P. Yarroll" <piggy@timesys.com>
Subject: Re: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch
Message-ID: <20040723054735.GA14108@elte.hu>
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* Nick Piggin <nickpiggin@yahoo.com.au> 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.

	Ingo