Messages in this thread | | | Date | Sun, 28 Mar 2004 13:59:17 -0700 | From | "Eric D. Mudama" <> | Subject | Re: [PATCH] speed up SATA |
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Er, forgot about the queue depth of only 2...
Even in that case, you'll more than likely still get better throughput with a single 32-MB command... If you send a pair of queued commands down, and the 2nd one is chosen, there's no reason that the first one won't get starved until the very end of the request, which would have bad latency on that command.
Even worse, would be it getting force-promoted in the middle of the rest of the 32MB chunk due to an approaching internal timeout, and therefore interrupting a 31-MB sequential read to do a 1MB read.
However, most of this is silly... 32 1MB requests will be way faster than 32,000 1LBA requests, etc... in general, bigger requests = better throughput for all but a few specific workloads that I can think of off the top of my head. (lots of simultaneous stream workloads with very low latency requirements per-stream, for example)
-- Eric D. Mudama edmudama@mail.bounceswoosh.org
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