Re: [RFC PATCH 3/3] sched: introduce synchronized idle injection

Jacob Pan
2015-11-05T19:28:29Z

On Thu, 5 Nov 2015 11:09:22 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> > Before:
> > CPU0 ______||| || |___________| || || |_____
> > CPU1 _________||| || |_______| || |_______
> >
> > After:
> >
> > CPU0 ______||| || |___________| || || |_____
> > CPU1 ______||| || |___________| || |_______
> >
> > The goal is to have overlapping idle time if the load is already
> > balanced. The energy saving can be significant.
>
> I can see such a scheme having a fairly big impact on latency, esp.
> with forced idleness such as this. That's not going to be popular for
> many workloads.
agreed, it would be for limited workload. the key is to identify such
workloads at runtime. I am thinking to use the load average of
the busiest CPU as reference for consolidation, will not go beyond
that.
For the patch I have today and if you play a game like this one