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Re: [PATCH] Remove l_flushsema

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH] Remove l_flushsema
From: David Chinner <dgc@xxxxxxx>
Date: Wed, 30 Apr 2008 21:11:54 +1000
Cc: David Chinner <dgc@xxxxxxx>, Matthew Wilcox <matthew@xxxxxx>, xfs@xxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx
In-reply-to: <20080430105832.GA20442@infradead.org>
References: <20080430090502.GH14976@parisc-linux.org> <20080430104125.GM108924158@sgi.com> <20080430105832.GA20442@infradead.org>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Mutt/1.4.2.1i
On Wed, Apr 30, 2008 at 06:58:32AM -0400, Christoph Hellwig wrote:
> 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.

Yeah, I just realised that myself and was about to reply as such....

I'll move the wakeup outside the lock.

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group


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