On Tue, Dec 18, 2012 at 11:14:25AM -0800, Tejun Heo wrote: > Hello, Vivek. > > On Tue, Dec 18, 2012 at 02:11:17PM -0500, Vivek Goyal wrote: > > All these stats needs to be mentioned in blkio-controller.txt file to > > keep that file uptodate. > > > > I think it also needs another word about nature of hierarchical stats. > > That is they represent current view of the system and don't store the > > history. So if a cgroup was created, did some IO and it was removed, we > > lost that history. Deleted cgroup's parent will have no history of > > stats of deleted cgroup. > > Haven't thought about that. That's nasty. > > > Hence these stats can't be used for things like billing purposes. > > > > IIRC, this is different from the way we collect hierarhical stats for > > memory controller. > > > > But I kind of like this because stat update overhead does not increase > > with depth of hierarchy. Primarily stat reader pays the price of > > traversing through all the stats. > > Yeah, hmmm, maybe we should add another set of counters to carry stats > from dead ones? Avoiding hierarchical accounting overhead in hot path > while remembering by-gones shouldn't be that hard. Will work on that. So are you planning to migrate the stats to parent when a cgroup is being deleted? That should make sure we don't do hierarhical update. Thanks Vivek _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
