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

Jacob Pan
2015-11-06T23:50:25Z

On Fri, 6 Nov 2015 08:45:10 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> On Thu, Nov 05, 2015 at 03:36:25PM -0800, Jacob Pan wrote:
>
> > I did some testing with the code below, it shows random
> > [ 150.442597] NOHZ: local_softirq_pending 02
> > [ 153.032673] NOHZ: local_softirq_pending 202
> > [ 153.203785] NOHZ: local_softirq_pending 202
> > [ 153.206486] NOHZ: local_softirq_pending 282
> > I recalled that was why i checked for local_softirq_pending in the
> > initial patch, still trying to find out how we can avoid that. These
> > also causes non stop sched ticks in the inner idle loop.
>
> Check the softirq stuff before calling throttle ?

yes, played with it but it seems there are other cases causing pending
softirq in idle in addition to throttle. I still haven't figure it out,
this problem only shows up in heavy irq, network load. e.g. compile
kernel over NFS. Debugging.