I though that NCQ was intended to increase performance ??
intended to increase _sales_ performance ;)
remember that you've always had command queueing (kernel elevator):
the main difference with NCQ (or SCSI tagged queueing) is when
the disk can out-schedule the kernel. afaikt, this means sqeezing
in a rotationally intermediate request along the way.
that intermediate request must be fairly small and should be a read
(for head-settling reasons).
I wonder how often this happens in the real world, given the relatively
small queues the disk has to work with.
My hdparm test is a sequential read-ahead test, so it will
naturally perform worse on a Raptor when NCQ is on.
that's a surprisingly naive heuristic, especially since
NCQ is concerned with just a max of ~4MB of reads, only a smallish
fraction of the available cache.
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