Re: [PATCH] speed up SATA

From: Jeff Garzik
Date: Sat Mar 27 2004 - 20:11:32 EST

Andrew Morton wrote:
Jeff Garzik <jgarzik@xxxxxxxxx> 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.

Slightly beneficial for throughput, disastrous for latency.

If the disk is smart there are surely opportunities for latency optimization as well...

It appears the only way we'll ever get this gross misdesign fixed is to add
a latency test to winbench.

rotfl ;-) True that...

"IOPs" are what make a lot of storage peeps excited these days, so they are being pushed in a low-latency direction anyway.


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