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Message-ID: <75b66ecd0703292144x2dd9df30y3c316d54d2e5f7d@mail.gmail.com>
Date: Fri, 30 Mar 2007 00:44:44 -0400
From: "Lee Revell" <rlrevell@joe-job.com>
To: "Nick Piggin" <npiggin@suse.de>
Subject: Re: [patch] queued spinlocks (i386)
Cc: "Davide Libenzi" <davidel@xmailserver.org>,
       "Oleg Nesterov" <oleg@tv-sign.ru>,
       "Ravikiran G Thirumalai" <kiran@scalex86.org>,
       "Ingo Molnar" <mingo@elte.hu>, "Nikita Danilov" <nikita@clusterfs.com>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
       "Eric Dumazet" <dada1@cosmosbay.com>
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On 3/29/07, Nick Piggin <npiggin@suse.de> wrote:
> On Thu, Mar 29, 2007 at 10:06:41PM -0400, Lee Revell wrote:
> > Until someone fixes all the places in the kernel where scheduling can
> > be held off for tens of milliseconds, CONFIG_PREEMPT will be an
> > absolute requirement for many applications like audio and gaming.
>
> There's nothing wrong with CONFIG_PREEMPT for those users. We have
> a few other performance concessions activated with CONFIG_PREEMPT on.
> I think a usual upper of a few miliseconds (especially for SMP) is
> reasonable for a non preempt kernel.

This is within reach - the only major offender left is
rt_secret_rebuild (and possibly other areas of the route cache
handling).  Eric Dumazet had some suggestions to fix it, but the
details are beyond my area of expertise.

Lee