Re: [RFC PATCH 7/9] housekeeping: Use own boot option, independant from nohz

From: Mike Galbraith
Date: Wed Aug 16 2017 - 14:01:47 EST


On Tue, 2017-08-15 at 11:26 -0500, Christopher Lameter wrote:
> On Tue, 15 Aug 2017, Mike Galbraith wrote:
>
> > On Tue, 2017-08-15 at 10:52 -0500, Christopher Lameter wrote:
> > > On Tue, 15 Aug 2017, Paul E. McKenney wrote:
> > >
> > > > Don't the HPC guys just disable idle_balance(), or am I out of date again?
> > >
> > > Ummm.. Why does idle management matter when your goal is to keep all
> > > processor busy working at maximum throughput?
> >
> > If you _never_ idle, you never have to worry about it. ÂIs 100% CPU
> > until the end of time all there is to HPC?
>
> Most of the time that is true for HPC loads. They may also go through a
> I/O throughput constrained processing phase or synchronization phase where
> idle activity occurs.

That synchronization is what I tend to get all hung up on pondering HPC
vs RT terminology. ÂCare and feeding of parallel pipelines has got to
be loaded to the gills with synchronization (intermediate math results
etc), rendering the sum event driven.

Doesn't matter, both acronyms reduce to latency intolerant.

-Mike