Andrew Morton wrote:
> Patrick Mansfield <patmans@us.ibm.com> wrote:
[...]
>
>>The larger queue depths can be nice for disk arrays with lots of cache and
>>(more) random IO patterns.
>
>
> So says the scsi lore ;) Have you observed this yourself? Have you
> any numbers handy?
I believe deep queues might work well if the drives did their own
anticipatory scheduling. After all, they know both true geometry and
excact rotational position and latency.
But current drives aren't that good so all the deep queue achieves is
extra seeks which sometimes kills performance. The fix is simple -
shorten the queues. Long ones aren't really a goal by itself -
performance is.
Helge Hafting
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Feb 28 2003 - 22:00:35 EST