On 02/25/2016 04:13 PM, Daniel Bristot de Oliveira wrote: > On 02/25/2016 11:18 AM, Sebastian Andrzej Siewior wrote: >> not that I am aware of. There are a few per-CPU threads which have to >> stay the way they are. I would have expected that others like kworker/u* >> respect the isol CPUs and stay away. > > Isolcpus is applied only for user-space threads. For instance, you > still need to move rcu offload callbacks away from isolated CPUs, and > all other kernel threads as well. RCU is special since this is a per-CPU thread. However Paul did make an option where you can move those to another CPU. > In the special case of kworker/u* threads, you need to use a special > interface to do it. The interface is the following file: > > /sys/devices/virtual/workqueue/cpumask I see it documented in "Documentation/ABI". Oh wait… > It was implemented on the following commit: > > 042f7df workqueue: Allow modifying low level unbound workqueue cpumask > > But the default CPU mask is the "cpu_possible_mask". > > Sometime ago I sent a patch to modify the default mask of the kworker/u* > threads, to avoid them on isolated CPUs by default, but it was not > acked. It was not explicitly nacked, though. > > http://www.gossamer-threads.com/lists/linux/kernel/2218495 > > Should I try it again? Atleast they do have a default cpumask which you can modify. I don't see why the kworker should be special here and avoid the isolcpu mask. I *do* support the default mask being !isolcpus and not cpu_possible. If you have the time to try again, please do so. > > -- Daniel > Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
