From: Tejun Heo <htejun@gmail.com>
To: Jeff Garzik <jeff@garzik.org>
Cc: Carlo Wood <carlo@alinoe.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: Sat, 23 Jun 2007 16:54:16 +0900 [thread overview]
Message-ID: <467CD1A8.5070700@gmail.com> (raw)
In-Reply-To: <467CC5C5.6040201@garzik.org>
Jeff Garzik wrote:
> Carlo Wood wrote:
>> The dmesg output of 33480a0ede8dcc7e6483054279008f972bd56fd3 (thus
>> "before") is:
> [...]
>> And the dmesg output of 551c012d7eea3dc5ec063c7ff9c718d39e77634f (thus
>> "after") is:
> [...]
>
> Your disk configurations are quite radically different between the two
> kernels (see attached diff for key highlights).
>
> The new behavior of the more recent kernel (551c012d7...) is that it now
> fully drives your hardware :) The reset problems go away, NCQ is
> enabled, and if you had 3.0Gbps drives (you don't) they would be driven
> at a faster speed.
>
> Given that some drives might be better tuned for benchmarks in
> non-queued mode, and that a major behavior difference is that your
> drives are now NCQ-enabled, the first thing I would suggest you try is
> disabling NCQ:
> http://linux-ata.org/faq.html#ncq
>
> Other indicators are the other changes in the "ahci 0000:00:1f.2:
> flags:" line, which do affect other behaviors, though none so important
> to RAID5 performance as NCQ, I would think.
>
> Turning on NCQ also potentially affects barrier behavior in RAID, though
> I'm guessing that is not a factor here.
Ah.. right. That should have enabled NCQ. Me slow today. :-)
--
tejun
next prev parent reply other threads:[~2007-06-23 7:54 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-20 22:48 SATA Harddisk speed drop of 100 MB/s Carlo Wood
2007-06-20 23:06 ` Jeff Garzik
2007-06-21 3:36 ` Arjan van de Ven
2007-06-22 16:21 ` Carlo Wood
2007-06-22 21:17 ` Henrique de Moraes Holschuh
2007-06-22 21:27 ` Carlo Wood
2007-06-23 1:31 ` Henrique de Moraes Holschuh
2007-06-23 2:59 ` Carlo Wood
2007-06-23 17:29 ` Andrew Morton
2007-06-23 22:21 ` Jeff Garzik
2007-06-25 15:18 ` Lennart Sorensen
2007-06-25 16:04 ` Carlo Wood
2007-06-22 21:44 ` SATA RAID5 " Carlo Wood
2007-06-23 3:54 ` Carlo Wood
2007-06-23 6:22 ` Tejun Heo
2007-06-22 21:48 ` Carlo Wood
2007-06-23 7:03 ` Jeff Garzik
2007-06-23 7:54 ` Tejun Heo [this message]
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
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