Re: [RFC PATCH 12/12] rcu: Nocb (de)activate through sysfs

From: Paul E. McKenney
Date: Wed Sep 23 2020 - 11:47:18 EST


On Wed, Sep 23, 2020 at 05:27:46PM +0200, Frederic Weisbecker wrote:
> On Mon, Sep 21, 2020 at 05:26:29PM -0700, Paul E. McKenney wrote:
> > On Mon, Sep 21, 2020 at 02:43:51PM +0200, Frederic Weisbecker wrote:
> > > Not for merge.
> > >
> > > Make nocb toggable for a given CPU using:
> > > /sys/devices/system/cpu/cpu*/hotplug/nocb
> > >
> > > This is only intended for those who want to test this patchset. The real
> > > interfaces will be cpuset/isolation and rcutorture.
> >
> > Excellent choice for testing in the near term!
> >
> > How does rcutorture fare with this series if an additional kthread toggles
> > offloading on and off continually?
>
> So yeah that would be the plan: having something that randomly toggles
> offloading from the RCU tests themselves. I'm not quite familiar with
> rcutorture internals yet though.

If you supply a function that selects a CPU and does the toggle, I
can quickly and easily wire it into rcutorture. I of course have no
objection to your learning to do this yourself, but the offer stands.

> > All questions and concerns aside, excellent progress and nice work!!!
>
> Thanks! We are slowly making progress :)

Better than quickly failing to make progress, to be sure! ;-)

Thanx, Paul