From: Jens Axboe <jens.axboe@oracle.com>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: Jan Kara <jack@suse.cz>, LKML <linux-kernel@vger.kernel.org>,
Chris Mason <chris.mason@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Galbraith <efault@gmx.de>,
mszeredi@suse.de
Subject: Re: Performance regression in IO scheduler still there
Date: Thu, 12 Nov 2009 22:00:01 +0100 [thread overview]
Message-ID: <20091112210000.GO8742@kernel.dk> (raw)
In-Reply-To: <x49pr7npj71.fsf@segfault.boston.devel.redhat.com>
On Thu, Nov 12 2009, Jeff Moyer wrote:
> Jan Kara <jack@suse.cz> writes:
>
> > On Wed 11-11-09 12:43:30, Jeff Moyer wrote:
> >> Jan Kara <jack@suse.cz> writes:
> >>
> >> > Sadly, I don't see the improvement you can see :(. The numbers are the
> >> > same regardless low_latency set to 0:
> >> > 2.6.32-rc5 low_latency = 0:
> >> > 37.39 36.43 36.51 -> 36.776667 0.434920
> >> > But my testing environment is a plain SATA drive so that probably
> >> > explains the difference...
> >>
> >> I just retested (10 runs for each kernel) on a SATA disk with no NCQ
> >> support and I could not see a difference. I'll try to dig up a disk
> >> that support NCQ. Is that what you're using for testing?
> > I don't think I am. How do I find out?
>
> Good question. ;-) I grep for NCQ in dmesg output and make sure it's
> greater than 0/32. There may be a better way, though.
cat /sys/block/<dev>/device/queue_depth
:-)
--
Jens Axboe
next prev parent reply other threads:[~2009-11-12 21:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-26 17:20 Performance regression in IO scheduler still there Jan Kara
2009-10-26 17:26 ` Jeff Moyer
2009-11-05 20:10 ` Jeff Moyer
2009-11-05 23:00 ` Corrado Zoccolo
2009-11-06 14:14 ` Jeff Moyer
2009-11-10 18:37 ` Jan Kara
2009-11-06 18:56 ` Jeff Moyer
2009-11-08 17:01 ` Corrado Zoccolo
2009-11-10 16:47 ` Jeff Moyer
2009-11-10 17:37 ` Corrado Zoccolo
2009-11-11 14:10 ` Jan Kara
2009-11-11 17:43 ` Jeff Moyer
2009-11-12 17:29 ` Jan Kara
2009-11-12 20:44 ` Jeff Moyer
2009-11-12 21:00 ` Jens Axboe [this message]
2009-11-12 21:05 ` Jeff Moyer
2009-11-13 7:45 ` Jens Axboe
2009-11-16 10:47 ` Jan Kara
2009-11-16 16:58 ` Jan Kara
2009-11-16 17:03 ` Jeff Moyer
2009-11-16 18:38 ` Corrado Zoccolo
2009-11-16 22:17 ` Jan Kara
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