Messages in this thread | | | Date | Thu, 4 Sep 2008 16:03:43 -0700 | From | "Paul Menage" <> | Subject | Re: Default values for cpuset.mems, cpus for children created |
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On Fri, Aug 15, 2008 at 12:31 PM, Dhaval Giani <dhaval@linux.vnet.ibm.com> wrote: > Now an application programmer does not really care where and how > subsystems are mounted (or at least that is what libcgroup aims to > achieve :-) ). And such a scenario when the cpuset has not been handled > is going to lead to failures which a user is not expecting. > > To work around this, I am making a change which will just set the values > which the parent group has for unfilled values, but I can already see > cpuset breaking that assumption as well. (for example exclusive > cpusets).
Yes, this is an awkwardness with the cpusets model of recursively sharing a set of identifiable resources. Quite apart from the backwards compatibility issue, if you make new cpusets inherit their parent's resources you break the exclusive setting, and if you don't you require special setup before the cgroup can be used.
There's already a precedent in the cpuset_clone() function, which does inherit the parent's resources, but I don't think the clone behaviour is widely used, and even that doesn't handle the case of exclusive siblings.
I'm inclined to say that this is a userspace bug - if you don't want cpusets attached to your cgroup hierarchy, don't include them in the set of mounted subsystems.
Paul
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