On 07/20/2018 11:44 AM, Peter Zijlstra wrote: > On Fri, Jul 20, 2018 at 04:45:49AM -0700, Tejun Heo wrote: > >>>> Hmm... so a given ancestor must be able to both >>>> >>>> 1. control which cpus are moved into a partition in all of its >>>> subtree. >>> By virtue of the partition file being owned by the parent, this is >>> already achived, no? >> The currently proposed implementation is somewhere in the middle. It >> kinda gets there by restricting a partition to be a child of another >> partition, which may be okay but it does make the whole delegation >> mechanism less useful. > So the implementation does not set ownership of the 'partition' file to > that of the parent directory? Because _that_ is what I understood from > Waiman (many versions ago). And that _does_ allow delegation to work > nicely. > >>>> 2. take away any given cpu from ist subtree. >>> I really hate this obsession of yours and doubly so for partitions. But >>> why would this currently not be allowed? >> Well, sorry that you hate it. It's a fundamental architectural >> constraint. If it can't satisfy that, it should't be in cgroup. > So is hierarchical behaviour; but you seem willing to forgo that. > > Still, the question was, how is this (dispicable or not) behaviour not > allowed by the current implementation? The taking CPUs away part is not functioning yet in the current patchset. It is certainly doable. I just need more time to work on that. The current patchset is fine if partition is restricted to the first level children as CPU online/offline is properly handled by the patchset. It is in the non-root level that taking CPUs away from a partition can be problematic. Cheers, Longman -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
