From: Mark Lord <liml@rtr.ca>
To: Gentoopower <gentoopower@yahoo.de>
Cc: "Raz Ben-Jehuda(caro)" <raziebe@gmail.com>,
Linux RAID Mailing List <linux-raid@vger.kernel.org>,
"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>
Subject: Re: NCQ general question
Date: Wed, 01 Mar 2006 08:49:10 -0500 [thread overview]
Message-ID: <4405A656.1030602@rtr.ca> (raw)
In-Reply-To: <440561CB.30201@yahoo.de>
Gentoopower wrote:
> Raz Ben-Jehuda(caro) wrote:
>> i am thinking of buying a promise card sataII pcix.
>> they have two types, a card which support NCQ
>> and another that does not.
>> What is the bennifit of buying a card with NCQ tagging ?
>>
> How about: http://en.wikipedia.org/wiki/Native_command_queueing
Yuck.. what a lousy wiki entry.
NCQ vs. TCQ: NCQ has a much more efficient low-level protocol,
making the host-side (controller, operating-system) quite a bit
simpler than with NCQ.
Both use 32-deep queue depths, and neither of them are worth a
damn on Linux yet. Except possibly in the libata ahci driver,
or vendor-provided drivers (open source, even) for some chipsets.
In theory, NCQ/TCQ can speed up a very busy fileserver that is
handling mostly tiny I/O requests. Practically no measurable
benefit for single-user systems.
Cheers
next prev parent reply other threads:[~2006-03-01 13:49 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-01 7:04 NCQ general question Raz Ben-Jehuda(caro)
2006-03-01 8:56 ` Gentoopower
2006-03-01 13:49 ` Mark Lord [this message]
2006-03-01 13:55 ` Jens Axboe
2006-03-03 21:55 ` Steve Byan
2006-03-03 22:19 ` Jeff Garzik
2006-03-04 18:56 ` Steve Byan
2006-03-04 19:10 ` Jeff Garzik
2006-03-04 20:23 ` Steve Byan
2006-03-04 23:56 ` Eric D. Mudama
2006-03-05 7:19 ` Raz Ben-Jehuda(caro)
2006-03-05 7:29 ` Jeff Garzik
2006-03-08 16:51 ` Louis-David Mitterrand
2006-03-08 17:17 ` Jeff Garzik
2006-03-14 17:17 ` Louis-David Mitterrand
2006-03-01 15:56 ` Gentoopower
2006-03-01 16:05 ` Jens Axboe
2006-03-01 16:20 ` Jeff Garzik
2006-03-01 18:53 ` Jens Axboe
2006-03-02 8:14 ` Raz Ben-Jehuda(caro)
2006-03-02 8:18 ` Jens Axboe
2006-03-02 11:20 ` Jeff Garzik
2006-03-02 13:34 ` Raz Ben-Jehuda(caro)
2006-03-02 13:37 ` Jeff Garzik
2006-03-02 8:18 ` Rafal Krzewski
2006-03-02 11:35 ` Jeff Garzik
2006-03-02 14:29 ` Rafal Krzewski
2006-03-01 16:48 ` Gentoopower
2006-03-01 18:34 ` Mark Lord
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