Messages in this thread | | | Date | Mon, 11 Jan 2010 06:25:29 -0500 | From | Jeff Garzik <> | Subject | Re: [PATCH] cfq-iosched: NCQ SSDs do not need read queue merging |
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On 01/10/2010 04:04 PM, Corrado Zoccolo wrote: > NCQ SSDs' performances are not affected by > distance of read requests, so there is no point in having > overhead to merge such queues. > > Non-NCQ SSDs showed regression in some special cases, so > they are ruled out by this patch. > > This patch intentionally doesn't affect writes, so > it changes the queued[] field, to be indexed by > READ/WRITE instead of SYNC/ASYNC, and only compute proximity > for queues with WRITE requests. > > Signed-off-by: Corrado Zoccolo<czoccolo@gmail.com>
That's not really true. Overhead always increases as the total number of ATA commands issued increases.
Jeff
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