Re: [RFC patch 1/2] sched: dynamically adapt granularity with nr_running

Peter Zijlstra
2010-09-12T09:14:56Z

On Sun, 2010-09-12 at 11:06 +0200, Peter Zijlstra wrote:
> * is slice length, + is period length
>
> Patch (sched_latency = 10, sched_min_gran = 10/3)
>
>
> 30 | +
> |
> |
> | +
> |
> |
> |
> |
> |
> |
> 20 |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> 10 | * + + + + + + +
> |
> |
> |
> |
> | *
> |
> | * * * * * * * *
> | * *
> | * *
> 0 +---------------------------------------------------------
> 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Vertical is time , horz is nr_running.

Note how things fall of a cliff when nr_running goes from 8 to 9. Andrew
usually kicks people in the teeth for phase change behaviour.