On Tue, 16 Jan 2018 23:51:29 +0100 Frederic Weisbecker <frede...@kernel.org> wrote:
> On Tue, Jan 16, 2018 at 11:52:11AM -0500, Luiz Capitulino wrote: > > On Tue, 16 Jan 2018 16:41:00 +0100 > > Frederic Weisbecker <frede...@kernel.org> wrote: > > > So isolcpus= is now the place where we control the isolation features > > > and nohz is one of them. > > > > That's the part I'm not very sure about. We've been advising users to > > move away from isolcpus= when possible, but this very wanted nohz_offload > > feature will force everyone back to using isolcpus= again. > > Note "isolcpus=nohz" only implies nohz. You need to add "domain" to get > the behaviour that you've been advising users against. We are simply > reusing a kernel parameter that was abandoned to now control the isolation > features that were disorganized and opaque behind nohz. > > > > > I have the impression this series is trying to solve two problems: > > > > 1. How (and where) we control the various isolation features in the > > kernel > > No, that has already been done in the previous merge window. We have a > dedicated isolation subsystem now (kernel/sched/isolation.c) and > an interface to control all these isolation features that were abusively > implied > by nohz. The initial plan was to introduce "cpu_isolation=" but it looked too > much like > "isolcpus=". Then in fact, why not using "isolcpus=" and give it a second > life. > And there we are. OK, I get it now. But then series has to un-deprecate isolcpus= otherwise it doesn't make sense to use it.
