From: Jens Axboe <axboe@kernel.dk>
To: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] block: fix request sorting at unplug
Date: Mon, 04 Apr 2011 00:10:41 +0200 [thread overview]
Message-ID: <4D98F061.5030003@kernel.dk> (raw)
In-Reply-To: <20110402153737.15555.75762.stgit@localhost6>
On 2011-04-02 17:37, Konstantin Khlebnikov wrote:
> Comparison function for list_sort() must be anticommutative,
> otherwise it is not sorting in ordinary meaning.
>
> But fortunately list_sort() always check ((*cmp)(priv, a, b) <= 0)
> it not distinguish negative and zero, so comparison function can
> implement only less-or-equal instead of full three-way comparison.
Thanks, good catch! It's an optimization, so no breakage. But if you end
up often having > 1 queue plugged, it's a good optimization.
--
Jens Axboe
prev parent reply other threads:[~2011-04-03 22:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-02 15:37 [PATCH] block: fix request sorting at unplug Konstantin Khlebnikov
2011-04-03 22:10 ` Jens Axboe [this message]
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