linux-kernel - Re: [announce] "kill the Big Kernel Lock (BKL)" tree

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Date:	Thu, 15 May 2008 00:21:50 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Jonathan Corbet <corbet@....net>, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Alexander Viro <viro@....linux.org.uk>,
	linux-kernel@...r.kernel.org
Subject: Re: [announce] "kill the Big Kernel Lock (BKL)" tree

Linus Torvalds wrote:
> 
> On Thu, 15 May 2008, Andi Kleen wrote:
>> The goal less being to get rid of BKL in old drivers, but not 
>> requiring BKL in new drivers. Basically all BKL assumptions
>> in interfaces really should go.
> 
> No, we really do want to get rid of BKL in old drivers too. Or at least in 
> the interfaces.

In the interfaces definitely yes and all subsystems should have their
own lock_kernel calls, but why in the old drivers? For those it's very
unlikely they are used on any SMP system anyways (e.g. anything
depending on CONFIG_ISA) or if they do only on 2 CPU systems.

Of course if you can find someone to do the work it wouldn't be
bad, just wouldn't seem like a particularly useful investment of time to
me.

Also it would be bad if the people who did such conversions didn't
actually test it and that's a great danger with many old drivers because
nearly nobody has the hardware (and if they do it won't be in a SMP system)

-Andi

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