Re: [PATCH] speed up SATA

Jeff Garzik
2004-03-28T01:09:57Z

Andrew Morton wrote:
> Jeff Garzik <jgarzik@pobox.com> 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.

Jeff