Re: [PATCH] speed up SATA

[Jamie Lokier]

Jeff Garzik wrote:
> TCQ-on-write for ATA disks is yummy because you don't really know what 
> the heck the ATA disk is writing at the present time.  By the time the 
> Linux disk scheduler gets around to deciding it has a nicely merged and 
> scheduled set of requests, it may be totally wrong for the disk's IO 
> scheduler.  TCQ gives the disk a lot more power when the disk integrates 
> writes into its internal IO scheduling.

Does TCQ-on-write allow you to do ordered write commits, as with barriers,
but without needing full cache flushes, and still get good performance?

In principle I think the answer is yes, but what is the answer with
real disks in practice?

-- Jamie
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