On 07/07, Frederic Weisbecker wrote: > > On Tue, Jul 07, 2015 at 06:30:30PM +0200, Oleg Nesterov wrote: > > > > > Not only useless it even breaks nohz full. The housekeeping work > > > (general kernel internal code that user doesn't care much about) is > > > handled by a reduced set of CPUs in nohz full, precisely those that are > > > not included by nohz_full= kernel parameters. For example unbound > > > workqueues are handled by housekeeping CPUs. > > > > Confused... I do not see how workqueue_attrs->cpumask can depend on > > tick_nohz_full_mask or housekeeping_mask. Could you explain? > > People who want CPU isolation will likely write > /sys/devices/virtual/workqueue/cpumask to a reduced set of CPUs, typically > CPU 0 that is used for housekeeping in nohz full.
Well, khelper_wq is not WQ_SYSFS, so I am not sure this is possible. But this doesn't really matter, people can change cpu affinity. But "workqueues are handled by housekeeping CPUs" doesn't look right. > In fact we should add the code which initialize wq_unbound_cpumask > to housekeeping_mask automatically. Perhaps, but until then the changelog above looks really confusing, as if workqueue.c already does this automagically ;) Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
