Re: Playing with SATA NCQ

[Jens Axboe]

On Sun, May 29 2005, Michael Thonke wrote:
> >Nothing, unfortunately NCQ doesn't provided any way of doing ordered
> >tags. The only tunable is the queue_depth, you can set that anywhere
> >between 1 and 30.
> >
> >  
> >
> So way my drive got default 30 as queue_depth on AHCI as you mentoined
> in the next mail
> 2-4 should be suitable and enough/normal?

Yes, 30 will be default for basically anyone as ahci now advertises a
max depth of 30 and the drives typically all support a depth of 32. The
minimum value of those two is used.

Whether 2-4 is 'enough' depends on your workload. But usually 2-4 is
enough to get a nice speedup on heavier io, while still getting you good
latencies on the individual io.

-- 
Jens Axboe

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/