Re: [PATCH 4/5] sched/isolation: Residual 1Hz scheduler tick offload

From: Luiz Capitulino
Date: Tue Dec 19 2017 - 09:34:46 EST


On Tue, 19 Dec 2017 10:19:11 +0100
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Tue, Dec 19, 2017 at 04:23:57AM +0100, Frederic Weisbecker wrote:
> > When a CPU runs in full dynticks mode, a 1Hz tick remains in order to
> > keep the scheduler stats alive. However this residual tick is a burden
> > for Real-Time tasks that can't stand no interruption at all.
>
> I'm not sure that is accurate. RT doesn't necessarily have anything much
> to so with this. The tick is per definition very deterministic and thus
> should not be a problem.

What Frederic says is certainly true for HPC. But even for RT I'd say
this is a very nice feature, since it may reduce maximum latency.