Re: fair group scheduler not so fair?

From: Srivatsa Vaddagiri
Date: Wed May 28 2008 - 22:42:20 EST


On Wed, May 28, 2008 at 12:35:19PM -0600, Chris Friesen wrote:
> Srivatsa Vaddagiri wrote:
>
>> We seem to be skipping the last element in the task list always. In your
>> case, the lone task in Group a/b is always skipped because of this.
>
>> Updated patch (on top of 2.6.26-rc3 +
>> http://programming.kicks-ass.net/kernel-patches/sched-smp-group-fixes/)
>> below. Pls let me know how it fares!
>
> Looking much better, but still some fairness issues with more complex
> setups.
>
[snip]

> A 10-sec average was better, but we still see errors of 6%:
> 2478 72.8%
> 2477 64.0%
> 2479 63.2%

Yes I have observed that the delta from ideal fairness is much more than
desirable (although I used to get much better fairness with
2.6.25-rc1. Let me verify and get back).

--
Regards,
vatsa
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