Re: [REPORT] cfs-v4 vs sd-0.44

Ingo Molnar
2007-04-23T21:05:04Z

* Ingo Molnar <mingo@elte.hu> wrote:

> sorry, i was a bit imprecise here. There is a case where CFS can give
> out a 'loan' to tasks. The scheduler tick has a low resolution, so it
> is fundamentally inevitable [*] that tasks will run a bit more than
> they should, and at a heavy context-switching rates these errors can
> add up significantly. Furthermore, we want to batch up workloads.
>
> So CFS has a "no loans larger than sched_granularity_ns" policy (which
> defaults to 5msec), and it captures these sub-granularity 'loans' with
> nanosec accounting. This too is a very sane economic policy and is
> anti-infationary :-)

at which point i guess i should rename CFS to 'EFS' (the Economic Fair
Scheduler)? =B-)

Ingo