Re: [announce] [patch] Voluntary Kernel Preemption Patch

[Con Kolivas]

Ingo Molnar wrote:
> as most of you are probably aware of it, there have been complaints on
> lkml that the 2.6 kernel is not suitable for serious audio work due to
> high scheduling latencies (e.g. the Jackit people complained). I took a
> look at latencies and indeed 2.6.7 is pretty bad - latencies up to 50
> msec (!) can be easily triggered using common workloads, on fast 2GHz+
> x86 system - even when using the fully preemptible kernel!
>
> to solve this problem, Arjan van de Ven and I went over various kernel
> functions to determine their preemptability and we re-created from
> scratch a patch that is equivalent in performance to the 2.4 lowlatency
> patches but is different in design, impact and approach:
>
>   http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.7-bk20-H2

Looks nice.

I think you may have mixed up your trees. I think this change is the cfq 
bad allocation fix which I dont think is part of your voluntary 
preemption patch:

--- linux/drivers/block/cfq-iosched.c.orig	
+++ linux/drivers/block/cfq-iosched.c	

Otherwise, cheers! I'll give it a bit of a run and see what numbers come up.

Con

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