Re: Some NCQ numbers...

From: Bill Davidsen
Date: Mon Jul 09 2007 - 07:20:54 EST


Justin Piszcz wrote:


On Wed, 4 Jul 2007, Justin Piszcz wrote:

On Wed, 4 Jul 2007, Michael Tokarev wrote:

> Tejun Heo wrote:
>> Hello,
>>
>> Michael Tokarev wrote:
>>> Well. It looks like the results does not depend on the
>>> elevator. Originally I tried with deadline, and just
>>> re-ran the test with noop (hence the long delay with
>>> the answer) - changing linux elevator changes almost
>>> nothing in the results - modulo some random "fluctuations".
>>
>> I see. Thanks for testing.
>
> Here are actual results - the tests were still running when
> I replied yesterday.
>
> Again, this is Seagate ST3250620AS "desktop" drive, 7200RPM,
> 16Mb cache, 250Gb capacity. The tests were performed with
> queue depth = 64 (on mptsas), drive write cache is turned
> off.

I found AS scheduler to be the premium and best for single-user performance.

You want speed? Use AS.

http://home.comcast.net/~jpiszcz/sched/cfq_vs_as_vs_deadline_vs_noop.html



Does not include noop-- tested the main three though, renamed :)

http://home.comcast.net/~jpiszcz/sched/cfq_vs_as_vs_deadline.html

And for the archives:

p34-cfq,15696M,77114.3,99,311683,55.3333,184947,38.6667,79842.7,99,524065,41.3333,634.033,0.333333,16:100000:16/64,1043.33,8.33333,4419.33,11.6667,2942,17.3333,1178,10.3333,4192.67,12.3333,2619.33,19

p34-as,15696M,76202.3,99,443103,85,189716,34.6667,79552,99,507271,39.6667,607.067,0,16:100000:16/64,1153,10,13434,36,2769.67,16.3333,1201.67,10.6667,3951.33,12,2665.67,19

p34-deadline,15696M,76933.3,98.6667,386852,72,183016,29.6667,79530.7,99,512082,39.6667,678.567,0,16:100000:16/64,1230.33,10.3333,12349,32.3333,2945,17.3333,1258,11,8183,22.3333,2867,20.3333

I looked at these before, did you really run with a chunk size of just under 16GB, or does "15696M" have some inobvious meaning?

--
Bill Davidsen <davidsen@xxxxxxx>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
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