lkml.org 
[lkml]   [2004]   [Jul]   [22]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateThu, 22 Jul 2004 09:07:44 +0200
FromIngo Molnar <>
SubjectRe: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch
* Nick Piggin <nickpiggin@yahoo.com.au> wrote:

> Given that we're looking for something acceptable for 2.6, how about
> adding
>
> if (rt_task(current))
> 	kick ksoftirqd instead
> 
> Otherwise, what is the performance penalty of doing all softirq
> processing from ksoftirqd?

this is insufficient too. An RT task might be _waiting to run_ and
spending our time in a non-RT context (including the idle task) doing
softirq processing might delay it indefinitely.

what we could do is to add a rq->nr_running_rt and do the deferred
softirq processing unconditionally if (rq->nr_running_rt). I'd still add
a sysctl to make it unconditional for user processes too - if someone
really cares about latency and doesnt want to make all his tasks RT. 
I'll code this up for the next version of the patch.
	Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:04    [from the cache]
©2003-2008