Date: Wed, 15 Sep 2004 21:39:11 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Ricky Beam <jfbeam@bluetronic.net>
Cc: Linux Kernel Mail List <linux-kernel@vger.kernel.org>
Subject: Re: [patch] remove the BKL (Big Kernel Lock), this time for real
Message-ID: <20040915193911.GA17052@elte.hu>
References: <20040915155555.GA11019@elte.hu> <Pine.GSO.4.33.0409151300280.10693-100000@sweetums.bluetronic.net>
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* Ricky Beam <jfbeam@bluetronic.net> wrote:

> On Wed, 15 Sep 2004, Ingo Molnar wrote:
> >yes, but progress in this area seems to have slowed down, and people are
> >hurting from the latencies introduced by the BKL meanwhile. Who cares if
> >some rare big chunk of code runs under a semaphore, as long as it's
> >preemptable?
> 
> "as long as it's preemptable" is the key there.  Not all arch's can
> run with PREEMPT enabled (yet) -- sparc/sparc64 for but one.  And at
> the moment, PREEMPT is a bit on the hosed side.

there's no problem at all - with my patch you'll still get the other
advantage:

- there is no time wasted spinning on the BKL if there's BKL contention

so if a platform doesnt support PREEMPT (or a user doesnt enable it)
then BKS-holding kernel code wont be preempted of course.

	Ingo
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