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Re: [Xen-users] io scheduler


  • To: mogensv@xxxxxxxxxxxxxxxx
  • From: Anand <xen.mails@xxxxxxxxx>
  • Date: Tue, 10 Jan 2006 16:44:50 +0530
  • Cc: Xen Users <Xen-users@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Tue, 10 Jan 2006 11:21:10 +0000
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>As you've seen for yourself, the scheduler can be changed runtime, and
>likewise as a boot option.

Yes the option is elevator=scheduler_name. However i tried that out with the domU, it doesn't work. The default scheduler is noop.

>My understanding is that schedulers works fairly directly on hardware,
>at least reorganizing disk queues, I -think- you cannot have different
>schedulers for dom0 and domU's.

>Why would you? It's the same physical disk...
>I believe cfq is usually considered the most versatile, unless specific
>needs are determined.

Well thats what i am confused with. On my machine, the dom0 is running anticipatory as default and domU is running noop.

Any ideas ?

On non-xen, yes. There's some benchmarks somewhere (don't seem to find
them right now) about advanteges of the various ones.
/usr/src/linux/Documentation/kernel-parameters.txt  says a few words.

As you've seen for yourself, the scheduler can be changed runtime, and
likewise as a boot option.
My understanding is that schedulers works fairly directly on hardware,
at least reorganizing disk queues, I -think- you cannot have different
schedulers for dom0 and domU's.
Why would you? It's the same physical disk...
I believe cfq is usually considered the most versatile, unless specific
needs are determined.

--
Kind regards,
Mogens Valentin




--

regards,

Anand
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