From: Phillip Susi <psusi@cfl.rr.com>
To: Michael Tokarev <mjt@tls.msk.ru>
Cc: Jeff Garzik <jeff@garzik.org>, Carlo Wood <carlo@alinoe.com>,
Tejun Heo <htejun@gmail.com>, Manoj Kasichainula <manoj@io.com>,
linux-kernel@vger.kernel.org,
IDE/ATA development list <linux-ide@vger.kernel.org>
Subject: Re: SATA RAID5 speed drop of 100 MB/s
Date: Thu, 05 Jul 2007 18:12:49 -0400 [thread overview]
Message-ID: <468D6CE1.8050808@cfl.rr.com> (raw)
In-Reply-To: <467E5C5E.6000706@msgid.tls.msk.ru>
Michael Tokarev wrote:
> Single Seagate 74Gb SCSI drive (10KRPM)
>
> BlkSz Trd linRd rndRd linWr rndWr linR/W rndR/W
> 4k 1 66.4 0.5 0.6 0.5 0.6/ 0.6 0.4/ 0.2
> 2 0.6 0.6 0.5/ 0.1
> 4 0.7 0.6 0.6/ 0.2
> 16k 1 84.8 2.0 2.5 1.9 2.5/ 2.5 1.6/ 0.6
> 2 2.3 2.1 2.0/ 0.6
> 4 2.7 2.5 2.3/ 0.6
> 64k 1 84.8 7.4 9.3 7.2 9.4/ 9.3 5.8/ 2.2
> 2 8.6 7.9 7.3/ 2.1
> 4 9.9 9.1 8.1/ 2.2
> 128k 1 84.8 13.6 16.7 12.9 16.9/16.6 10.6/ 3.9
> 2 15.6 14.4 13.5/ 3.2
> 4 17.9 16.4 15.7/ 2.7
> 512k 1 84.9 34.0 41.9 33.3 29.0/27.1 22.4/13.2
> 2 36.9 34.5 30.7/ 8.1
> 4 40.5 38.1 33.2/ 8.3
> 1024k 1 83.1 36.0 55.8 34.6 28.2/27.6 20.3/19.4
> 2 45.2 44.1 36.4/ 9.9
> 4 48.1 47.6 40.7/ 7.1
>
<snip>
> The only thing I don't understand is why with larger I/O block
> size we see write speed drop with multiple threads.
Huh? Your data table does not show larger block size dropping write
speed. 47.6 > 38.1 > 16.4.
> And in contrast to the above, here's another test run, now
> with Seagate SATA ST3250620AS ("desktop" class) 250GB
> 7200RPM drive:
>
> BlkSz Trd linRd rndRd linWr rndWr linR/W rndR/W
> 4k 1 47.5 0.3 0.5 0.3 0.3/ 0.3 0.1/ 0.1
> 2 0.3 0.3 0.2/ 0.1
> 4 0.3 0.3 0.2/ 0.2
> 16k 1 78.4 1.1 1.8 1.1 0.9/ 0.9 0.6/ 0.6
> 2 1.2 1.1 0.6/ 0.6
> 4 1.3 1.2 0.6/ 0.6
> 64k 1 78.4 4.3 6.7 4.0 3.5/ 3.5 2.1/ 2.2
> 2 4.5 4.1 2.2/ 2.3
> 4 4.7 4.2 2.3/ 2.4
> 128k 1 78.4 8.0 12.6 7.2 6.2/ 6.2 3.9/ 3.8
> 2 8.2 7.3 4.1/ 4.0
> 4 8.7 7.7 4.3/ 4.3
> 512k 1 78.5 23.1 34.0 20.3 17.1/17.1 11.3/10.7
> 2 23.5 20.6 11.3/11.4
> 4 24.7 21.3 11.6/11.8
> 1024k 1 78.4 34.1 33.5 24.6 19.6/19.5 16.0/12.7
> 2 33.3 24.6 15.4/13.8
> 4 34.3 25.0 14.7/15.0
>
> Here, the (total) I/O speed does not depend on the number
> of threads. From which I conclude that the drive does
> not reorder/optimize commands internally, even if NCQ is
> enabled (queue depth is 32).
While the difference does not appear to be as pronounced as with the WD
drive, the data does show more threads give more total IO. 4.7 > 4.5 >
4.3 in the 64k rndRd test, and the other tests show an increase with
more threads as well.
next prev parent reply other threads:[~2007-07-05 22:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20070620224847.GA5488@alinoe.com>
[not found] ` <4679B2DE.9090903@garzik.org>
[not found] ` <20070622214859.GC6970@alinoe.com>
2007-06-23 7:03 ` SATA RAID5 speed drop of 100 MB/s Jeff Garzik
2007-06-23 7:54 ` Tejun Heo
2007-06-23 12:53 ` Carlo Wood
2007-06-23 17:30 ` Bartlomiej Zolnierkiewicz
2007-06-23 22:43 ` Jeff Garzik
2007-06-24 11:58 ` Michael Tokarev
2007-06-24 12:59 ` Dr. David Alan Gilbert
2007-06-24 14:21 ` Justin Piszcz
2007-06-24 15:52 ` Michael Tokarev
2007-06-24 16:59 ` Justin Piszcz
2007-06-24 22:07 ` Carlo Wood
2007-06-24 23:46 ` Mark Lord
2007-06-25 0:23 ` Patrick Mau
2007-06-24 15:48 ` Michael Tokarev
2007-07-05 22:12 ` Phillip Susi [this message]
2007-06-24 0:54 ` Eyal Lebedinsky
2007-06-24 9:01 Mikael Pettersson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=468D6CE1.8050808@cfl.rr.com \
--to=psusi@cfl.rr.com \
--cc=carlo@alinoe.com \
--cc=htejun@gmail.com \
--cc=jeff@garzik.org \
--cc=linux-ide@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=manoj@io.com \
--cc=mjt@tls.msk.ru \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).