linux-kernel - Re: Requirements to control kernel isolation/nohz

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Date:   Thu, 10 Sep 2020 00:38:56 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Marcelo Tosatti <mtosatti@...hat.com>
Cc:     Phil Auld <pauld@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        linux-kernel@...r.kernel.org
Subject: Re: Requirements to control kernel isolation/nohz_full at runtime

On Thu, Sep 03, 2020 at 03:52:00PM -0300, Marcelo Tosatti wrote:
> On Thu, Sep 03, 2020 at 02:36:36PM -0400, Phil Auld wrote:
> > exclusive cpusets is used now to control scheduler load balancing on
> > a group of cpus.  It seems to me that this is the same idea and is part
> > of the isolation concept.  Having a toggle for each subsystem/feature in
> > cpusets could provide the needed userspace api. 
> > 
> > Under the covers it might be implemented as twiddling various cpumasks.
> > 
> > We need to be shifting to managing load balancing with cpusets anyway.
> 
> OK, adding a new file per isolation feature:
> 
> 	- cpuset.isolation_nohz_full
> 	- cpuset.isolation_kthread
> 	- cpuset.isolation_time
> 
> With a bool value per file, is an option.

Exactly. I would merge kthread/timers/workqueue into
cpuset.isolation.unbound though. Unless anyone may need more
granularity there?