linux-kernel - Re: Question about group scheduler cpu shares

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Message-ID: <1469155888.3862.26.camel@gmail.com>
Date:	Fri, 22 Jul 2016 04:51:28 +0200
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Gaurav Poothia <gaurav.poothia@...il.com>,
	linux-kernel@...r.kernel.org, peterz@...radead.org,
	mingo@...hat.com
Subject: Re: Question about group scheduler cpu shares

On Thu, 2016-07-21 at 18:18 -0700, Gaurav Poothia wrote:

> > ROOT
> > > 
> > + -Group1(3072)
> > >    |
> > >   +- A(2048)
> > >    |
> > >    +- B(1024)
> > > 
> > +- Group2(2048)
> >      |
> >      +-C(1024)
> >      |
> >      +-D(1024)
> > 

> > Say I add a task E to Group1's task list (note that is an interior aka
> > non-leaf node)
> > How does the CPU split change between A, B and E.
> > AFAICT there is no cgroup cpu subsystem knob to weight tasks on an
> > interior node against the tasks in that node's children

A, B and E are all entities with a weight, so just plug E into your
graph.  Its weight is determined by nice level, which is what cgroups
should have done instead of inventing shares IMHO.  1024 == nice(0).

	-Mike