Date: Mon, 30 May 2005 08:07:50 +0200
From: Jens Axboe <axboe@suse.de>
To: Michael Thonke <iogl64nx@gmail.com>
Cc: Jeff Garzik <jgarzik@pobox.com>, linux-ide@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: Playing with SATA NCQ
Message-ID: <20050530060749.GD7054@suse.de>
References: <20050526140058.GR1419@suse.de> <429793C8.8090007@gmail.com> <42979C4F.8020007@pobox.com> <42979FA3.1010106@gmail.com> <20050528121258.GA17869@suse.de> <4299BD23.6010004@gmail.com> <20050529190259.GA29770@suse.de> <429A2238.8010604@gmail.com>
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On Sun, May 29 2005, Michael Thonke wrote:
> >Nothing, unfortunately NCQ doesn't provided any way of doing ordered
> >tags. The only tunable is the queue_depth, you can set that anywhere
> >between 1 and 30.
> >
> >  
> >
> So way my drive got default 30 as queue_depth on AHCI as you mentoined
> in the next mail
> 2-4 should be suitable and enough/normal?

Yes, 30 will be default for basically anyone as ahci now advertises a
max depth of 30 and the drives typically all support a depth of 32. The
minimum value of those two is used.

Whether 2-4 is 'enough' depends on your workload. But usually 2-4 is
enough to get a nice speedup on heavier io, while still getting you good
latencies on the individual io.

-- 
Jens Axboe

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