Messages in this thread | | | Date | Fri, 15 May 2020 00:49:13 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 07/10] rcu: Temporarily assume that nohz full CPUs might not be NOCB |
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On Thu, May 14, 2020 at 08:50:32AM -0700, Paul E. McKenney wrote: > On Thu, May 14, 2020 at 01:08:28AM +0200, Frederic Weisbecker wrote: > > On Wed, May 13, 2020 at 11:25:27AM -0700, Paul E. McKenney wrote: > > > On Wed, May 13, 2020 at 06:47:11PM +0200, Frederic Weisbecker wrote: > > > > So far nohz_full CPUs had to be nocb. This requirement may change > > > > temporarily as we are working on preparing RCU to be able to toggle the > > > > nocb state of a CPU. Once that is done and nohz_full can be toggled as > > > > well dynamically, we'll restore that initial requirement. > > > > > > Would it simplify anything to make the CPU exit nohz_full first and > > > then exit rcu_nocb and vice versa in the other direction? That way the > > > assumption about nohz_full CPUs always being rcu_nocb could remain while > > > still allowing runtime changes to both states. > > > > That's the future plan but for now nohz_full can't even be exited yet. > > RCU is unlucky enough to be chosen as the starting point of this whole work :-) > > But testing could still start with CPUs marked rcu_nocb but not marked > nohz_full, right?
Ah! That makes sense indeed. I should indeed restrict de-offloading to CPUs that are not nohz_full.
> I must confess that I am a bit concerned about the increase in state space.
Yeah good point!
> Fair point, but I am also concerned about the welfare of the people > working on it. ;-)
Fair enough! :-)
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