From: Christoph Hellwig <hch@infradead.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: scameron@beardog.cce.hp.com, linux-scsi@vger.kernel.org,
stephenmcameron@gmail.com, dab@hp.com
Subject: Re: SCSI mid layer and high IOPS capable devices
Date: Thu, 13 Dec 2012 11:49:12 -0500 [thread overview]
Message-ID: <20121213164912.GA28496@infradead.org> (raw)
In-Reply-To: <50CA0692.2010903@acm.org>
On Thu, Dec 13, 2012 at 05:47:14PM +0100, Bart Van Assche wrote:
> From my experience with block and SCSI drivers option (1) doesn't
> look attractive from a performance point of view. From what I have
> seen performance with QD=1 is several times lower than performance
> with QD > 1. But maybe I overlooked something ?
What you might be missing is that at least on Linux no one who cares
about performance uses the Posix AIO inferface anyway, as the
implementation in glibc always has been horrible. The Linux-native
aio interface or the various thread pool implementations don't imply
useless ordering and thus can be used to fill up large queues.
next prev parent reply other threads:[~2012-12-13 16:49 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-11 0:00 SCSI mid layer and high IOPS capable devices scameron
2012-12-11 8:21 ` Bart Van Assche
2012-12-11 22:46 ` scameron
2012-12-13 11:40 ` Bart Van Assche
2012-12-13 18:03 ` scameron
2012-12-13 17:18 ` Bart Van Assche
2012-12-13 15:22 ` Bart Van Assche
2012-12-13 17:25 ` scameron
2012-12-13 16:47 ` Bart Van Assche
2012-12-13 16:49 ` Christoph Hellwig [this message]
2012-12-14 9:44 ` Bart Van Assche
2012-12-14 16:44 ` scameron
2012-12-14 16:15 ` Bart Van Assche
2012-12-14 19:55 ` scameron
2012-12-14 19:28 ` Bart Van Assche
2012-12-14 21:06 ` scameron
2012-12-15 9:40 ` Bart Van Assche
2012-12-19 14:23 ` Christoph Hellwig
2012-12-13 21:20 ` scameron
2012-12-14 0:22 ` Jack Wang
[not found] ` <CADzpL0TMT31yka98Zv0=53N4=pDZOc9+gacnvDWMbj+iZg4H5w@mail.gmail.com>
[not found] ` <006301cdd99c$35099b40$9f1cd1c0$@com>
[not found] ` <CADzpL0S5cfCRQftrxHij8KOjKj55psSJedmXLBQz1uQm_SC30A@mail.gmail.com>
2012-12-14 4:59 ` Jack Wang
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