From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] Remove l_flushsema
Date: Wed, 30 Apr 2008 06:58:32 -0400
Message-ID: <20080430105832.GA20442@infradead.org>
References: <20080430090502.GH14976@parisc-linux.org> <20080430104125.GM108924158@sgi.com>
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Cc: Matthew Wilcox <matthew@wil.cx>, xfs@oss.sgi.com,
	linux-fsdevel@vger.kernel.org
To: David Chinner <dgc@sgi.com>
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On Wed, Apr 30, 2008 at 08:41:25PM +1000, David Chinner wrote:
> The only thing that I'm concerned about here is that this will
> substantially increase the time the l_icloglock is held. This is
> a severely contended lock on large cpu count machines and putting
> the wakeup inside this lock will increase the hold time.
> 
> I guess I can address this by adding a new lock for the waitqueue
> in a separate patch set.

waitqueues are loked internally and don't need synchronization.  With
a little bit of re-arranging the code the wake_up could probably be
moved out of the critical section.