linux-kernel - RE: Why is NCQ enabled by default by libata? (2.6.20)

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Message-ID: <MDEHLPKNGKAHNMBLJOLKKEAICKAC.davids@webmaster.com>
Date:	Thu, 29 Mar 2007 14:47:20 -0700
From:	"David Schwartz" <davids@...master.com>
To:	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: RE: Why is NCQ enabled by default by libata? (2.6.20)

> But when writing, what is the difference between queuing multiple tagged 
> writes, and sending down multiple untagged cached writes that complete 
> immediately and actually hit the disk later?  Either way the host keeps 
> sending writes to the disk until it's buffers are full, and the disk is 
> constantly trying to commit those buffers to the media in the most 
> optimal order.

Which sounds faster to you:

1) "Do A, B, C, and D."
   "Okay, I've finished A, B, C, and B."
or

2) "Do A."
   "Okay." 
   "Do B."
   "Okay."
   "Do C."
   "Okay."
   "Do D."
   "Okay."

The first looks a bit more efficient to me.

	DS

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