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

From: Jacob Pan
Date: Thu Nov 05 2015 - 14:28:33 EST


On Thu, 5 Nov 2015 11:09:22 +0100
Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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
http://www.agame.com/game/cut-the-rope
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