Re: linux deadline i/o elevator tuning

On Apr 10, 2009, at 2:47 AM, Albe Laurenz *EXTERN* wrote:

> Grzegorz Jaskiewicz wrote:
>> acording to kernel folks, anticipatory scheduler is even better for
>> dbs.
>> Oh well, it probably means everyone has to test it on their own at
>> the
>> end of day.
>
> In my test case, noop and deadline performed well, deadline being a
> little
> better than noop.
>
> Both anticipatory and CFQ sucked big time.
>

This is my experience as well, I posted about playing with the
scheduler a while ago on -performance, but I can't seem to find it.

If you have a halfway OK raid controller, CFQ is useless. You can fire
up something such as pgbench or pgiosim, fire up an iostat and then
watch your iops jump high when you flip to noop or deadline and
plummet on cfq.  Try it. it's neat!

--
Jeff Trout <jeff@jefftrout.com>
http://www.stuarthamm.net/
http://www.dellsmartexitin.com/