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Date: Wed, 7 May 2008 10:27:59 -0700 (PDT)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Morton <akpm@linux-foundation.org>
cc: Matthew Wilcox <matthew@wil.cx>, Ingo Molnar <mingo@elte.hu>,
       "J. Bruce Fields" <bfields@citi.umich.edu>,
       "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
       LKML <linux-kernel@vger.kernel.org>,
       Alexander Viro <viro@ftp.linux.org.uk>, linux-fsdevel@vger.kernel.org
Subject: Re: AIM7 40% regression with 2.6.26-rc1
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On Wed, 7 May 2008, Andrew Morton wrote:

> On Wed, 7 May 2008 10:08:18 -0700 (PDT) Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
> > Which is why I'm 100% convinced it's not even worth saving the old code. 
> > It needs to use mutexes, or spinlocks. I bet it has *nothing* to do with 
> > "slow path" other than the fact that it gets to that slow path much more 
> > these days.
> 
> Stupid question: why doesn't lock_kernel() use a mutex?

Not stupid.

The only reason some code didn't get turned over to mutexes was literally 
that they didn't want the debugging because they were doing intentionally 
bad things. 

I think the BKL is one of them (the console semaphore was another, iirc). 

			Linus