Messages in this thread | | | Date | Wed, 9 Jul 2014 07:57:46 -0400 | From | Vivek Goyal <> | Subject | Re: [PATCH v2 6/6] blkcg, memcg: make blkcg depend on memcg on the default hierarchy |
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On Tue, Jul 08, 2014 at 05:53:51PM -0400, Tejun Heo wrote: > Hello, Vivek. > > On Tue, Jul 08, 2014 at 03:42:26PM -0400, Vivek Goyal wrote: > > I have couple questions about new semantics. Following is my > > understanding. Is it right? > > > > - So after this change one can not use blkio controller on unified > > hiearchy if memory controller is mounted on some other hierarchy > > and is not available for mounting unified hiearchy. > > Hmmm? No, the only behavior which changes is when both blkcg and > memcg are mounted on the unified hierarchy. Nothing else changes. > The dependency behavior kicks in iff memcg is available on the unified > hierarchy.
Ok, good to know that dependency kicks in only if controlle being depended on is available on the hierarchy. > > > - If blkio controller is enabled on unified hiearchy (memory controller > > implicitly enabled), then one can't mount memory controller on other > > hierarchies without first disabling blkio controller on unified hiearchy. > > Yes, blkio needs to be disabled to the root for memcg to be able to > become free. This is an extra restriction but I don't think it's > anything drastic. Once a controller starts being actively used on any > hierarchy, nothing has been guaranteed about when the controller would > become free again even if the whole hierarchy is reduced to the root.
Agreed. Thanks for the clarification.
Thanks Vivek
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