From: Robert Hancock <hancockr@shaw.ca>
To: Justin Piszcz <jpiszcz@lucidpixels.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Why is NCQ enabled by default by libata? (2.6.20)
Date: Sat, 24 Mar 2007 16:11:21 -0600 [thread overview]
Message-ID: <4605A209.9050808@shaw.ca> (raw)
In-Reply-To: <fa.MhN9pBMjZID4rnTNn+fU01uZiss@ifi.uio.no>
Justin Piszcz wrote:
> Without NCQ, performance is MUCH better on almost every operation, with
> the exception of 2-3 items.
>
> /usr/sbin/bonnie++ -d /x/bonnie -s 7952 -m p34 -n 16:100000:16:64 >
> run.txt;
>
> # Average of 3 runs with NCQ on for Quad Raptor ADFD 150 RAID 5 Software
> RAID:
> p34-ncq-on,7952M,43916.3,96.6667,151943,28.6667,75794.3,18.6667,48991.3,99,181687,24,558.033,0.333333,16:100000:16/64,867.667,9,29972.7,98.3333,2801.67,16,890.667,9.33333,27743,94.3333,2115.33,15.6667
>
> # Average of 3 runs with NCQ off for Quad Raptor ADFD 150 RAID 5
> Software RAID:
> p34-ncq-off,7952M,42470,97.3333,200409,36.3333,90240.3,22.6667,48656,99,198853,27,546.467,0,16:100000:16/64,972.333,10,21833,72.3333,3697,21,995,10.6667,27901.7,95.6667,2681,20.6667
>
>
> http://home.comcast.net/~jpiszcz/ncq_vs_noncq/results.html
>
> In general, for networking, etc, the kernel chooses 'optimized'
> defaults, therefore, I was curious why is NCQ enabled by default?
Normally NCQ is faster, though it depends on the drive firmware. It's
also possible that software RAID is a case where there are negative
interactions.
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/
next parent reply other threads:[~2007-03-24 22:12 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <fa.MhN9pBMjZID4rnTNn+fU01uZiss@ifi.uio.no>
2007-03-24 22:11 ` Robert Hancock [this message]
[not found] <fa.NmF2xJwO4BeVbJrFRkf7oV9EYmQ@ifi.uio.no>
[not found] ` <fa.39luedDWsoqip+QMNtfAv8jvyNg@ifi.uio.no>
[not found] ` <fa.b1cZfpMNhZ0teK/UauKLDWw60Jc@ifi.uio.no>
[not found] ` <fa.xWaBy6HZTRTgI+PxinV8ajuOlJI@ifi.uio.no>
[not found] ` <fa.BiSx71HKysC9QIpS8DLip5BmfxI@ifi.uio.no>
2007-04-01 17:28 ` Why is NCQ enabled by default by libata? (2.6.20) Robert Hancock
2007-03-27 16:16 linux
2007-03-27 16:25 ` Justin Piszcz
2007-03-27 16:41 ` linux
2007-03-27 16:44 ` Justin Piszcz
2007-03-27 16:58 ` linux
2007-03-27 17:03 ` Justin Piszcz
2007-03-28 14:42 ` Phillip Susi
2007-03-28 14:48 ` Jeff Garzik
2007-03-28 15:22 ` Andy Warner
2007-03-29 17:28 ` Phillip Susi
2007-03-29 18:40 ` linux
2007-03-29 18:51 ` Jeff Garzik
2007-03-29 21:35 ` Alan Cox
2007-03-29 21:47 ` David Schwartz
2007-03-30 16:33 ` Lennart Sorensen
-- strict thread matches above, loose matches on Subject: below --
2007-03-24 16:38 Justin Piszcz
2007-03-24 18:43 ` Alan Cox
2007-03-27 9:55 ` Justin Piszcz
2007-03-27 10:10 ` Tejun Heo
2007-03-27 10:30 ` Justin Piszcz
2007-03-27 5:59 ` Jeff Garzik
2007-03-27 14:26 ` Mark Lord
2007-03-27 18:18 ` Mark Rustad
2007-03-27 18:38 ` Jeff Garzik
2007-03-27 22:12 ` Mark Rustad
2007-03-31 12:55 ` Ric Wheeler
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