From owner-freebsd-current@FreeBSD.ORG  Tue Dec 15 09:41:56 2009
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 9C260106566B
	for <freebsd-current@freebsd.org>; Tue, 15 Dec 2009 09:41:56 +0000 (UTC)
	(envelope-from serenity@exscape.org)
Received: from ch-smtp01.sth.basefarm.net (ch-smtp01.sth.basefarm.net
	[80.76.149.212])
	by mx1.freebsd.org (Postfix) with ESMTP id 553E78FC0A
	for <freebsd-current@freebsd.org>; Tue, 15 Dec 2009 09:41:56 +0000 (UTC)
Received: from c83-253-248-99.bredband.comhem.se ([83.253.248.99]:35032
	helo=mx.exscape.org)
	by ch-smtp01.sth.basefarm.net with esmtp (Exim 4.68)
	(envelope-from <serenity@exscape.org>)
	id 1NKTuM-0000yc-5L; Tue, 15 Dec 2009 10:41:33 +0100
Received: from [192.168.1.5] (macbookpro [192.168.1.5])
	(using TLSv1 with cipher AES128-SHA (128/128 bits))
	(No client certificate requested)
	by mx.exscape.org (Postfix) with ESMTPSA id 0176C190F93;
	Tue, 15 Dec 2009 10:41:29 +0100 (CET)
Mime-Version: 1.0 (Apple Message framework v1077)
Content-Type: text/plain; charset=us-ascii
From: Thomas Backman <serenity@exscape.org>
In-Reply-To: <f83770800912150136u1fbabd2ak7b0cd15f85c0099f@mail.gmail.com>
Date: Tue, 15 Dec 2009 10:41:27 +0100
Content-Transfer-Encoding: quoted-printable
Message-Id: <260900B2-1EC8-47F9-B3FE-144943ADEA70@exscape.org>
References: <20091119004651.7432a6e4.nork@FreeBSD.org>
	<f83770800912150136u1fbabd2ak7b0cd15f85c0099f@mail.gmail.com>
To: Wes Peters <barnaclewes@gmail.com>
X-Mailer: Apple Mail (2.1077)
X-Originating-IP: 83.253.248.99
X-Scan-Result: No virus found in message 1NKTuM-0000yc-5L.
X-Scan-Signature: ch-smtp01.sth.basefarm.net 1NKTuM-0000yc-5L
	715838d63d3fbb10d60d6eae0ede458b
Cc: FreeBSD current <freebsd-current@freebsd.org>
Subject: Re: How do I use NCQ of Intel X25-E(SSD) on ahci(4)?
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 15 Dec 2009 09:41:56 -0000

On Dec 15, 2009, at 10:36 AM, Wes Peters wrote:

> On Wed, Nov 18, 2009 at 7:46 AM, Norikatsu Shigemura =
<nork@freebsd.org> wrote:
>> Hi Alexander!
>>=20
>>        I have a Intel 64GB SSD(X25-E) and a Western Digital Caviar =
Green
>>        1TB HDD (WD10EADS), and use them on ahci(4).  ahci(4) can use =
NCQ
>>        of WD10EADS, but doesn't use NCQ of X25-E.
>=20
> How useful is NCQ on an SSD?  Isn't the primary thrust of NCQ to allow
> the disk to reorder writes to optimize the seek pattern?
http://en.wikipedia.org/wiki/NCQ#NCQ_in_Solid-State_Drives :)

Regards,
Thmas=