Re: [PATCH RFC tip/core/rcu] Parallelize and economize NOCB kthread wakeups

Mike Galbraith
2014-07-03T05:48:45Z

On Wed, 2014-07-02 at 22:21 -0700, Paul E. McKenney wrote:
> On Thu, Jul 03, 2014 at 05:31:19AM +0200, Mike Galbraith wrote:

> > NO_HZ_FULL is a property of a set of CPUs. isolcpus is supposed to go
> > away as being a redundant interface to manage a single property of a set
> > of CPUs, but it's perfectly fine for NO_HZ_FULL to add an interface to
> > manage a single property of a set of CPUs. What am I missing?
>
> Well, for now, it can only be specified at build time or at boot time.
> In theory, it is possible to change a CPU from being callback-offloaded
> to not at runtime, but there would need to be an extremely good reason
> for adding that level of complexity. Lots of "fun" races in there...

Yeah, understood.

(still it's a NO_HZ_FULL wart though IMHO, would be prettier and more
usable if it eventually became unified with cpuset and learned how to
tap-dance properly;)

-Mike