On Tue Dec 15, 2009 at 11:41:03PM -0600, Leslie Rhorer wrote:
> It seems to have done so, yes. I've looked around the web trying to
> find some additional info, but I've come up empty handed. Perhaps someone
> here can answer at least one of my questions? I know that putting a value
> of 32 into /sys/block/<driveID>/device/queue_depth fully enables NCQ, and
> putting a value of 1 there disables NCQ. What do all the numbers in between
> do?
>
I believe the value sets the allowed queue length. A value of 1 thus
effectively disables queueing. Most ATA drives have a maximum queue
depth of 32 so this is usually set for fully enabling it (though I
believe it's recommended only to use 31 - this seems to be the default).
If you set it to 32 and the drive has a shorter maximum queue, the
kernel will use the drive's maximum instead.
Setting any value is permitted, there's just generally little point in
doing so.
Cheers,
Robin
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( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> |
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