Date: Wed, 8 Feb 2012 08:56:11 -0800
From: Tejun Heo <tj@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Shaohua Li <shaohua.li@intel.com>, Jens Axboe <axboe@kernel.dk>,
        Vivek Goyal <vgoyal@redhat.com>, lkml <linux-kernel@vger.kernel.org>,
        Knut Petersen <Knut_Petersen@t-online.de>, mroos@linux.ee
Subject: Re: [PATCH] block: strip out locking optimization in
 put_io_context()
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On Wed, Feb 08, 2012 at 08:49:20AM -0800, Tejun Heo wrote:
> I'm still a bit lost on where the regression is coming from and
> *suspecting* that queue_lock contention is making the reverse locking
> behave much worse than expected, so I mostly wanted to take that out
> and see what happens.

IOW, we can achieve about the same thing by adding another lock in
request_queue.  The goal is using an inner lock for ioc clearing so
that queue_lock doesn't have to be grabbed inside ioc lock.

Thanks.

-- 
tejun
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