Re: Why is NCQ enabled by default by libata? (2.6.20)

[Alan Cox]

O> 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.

On the controller side primarily you get to queue commands which means
you don't have a dead time period between the completion interrupt and
the next command being issued. Those times add up even when there is a
disk cache buffering the output
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