On Tue, Jul 11, 2017 at 05:12:39PM -0400, Waiman Long wrote: > On 07/11/2017 12:52 PM, Peter Zijlstra wrote: > > On Tue, Jul 11, 2017 at 10:14:42AM -0400, Waiman Long wrote: > > > >> The "join" was a special op for the children of cgroup root to join the > >> root as part of a threaded subtree. The children can instead use the > >> "enable" option to become a thread root which was the configuration > >> shown above. This behavior applied only to children of root. Down the > >> hierarchy, you can't have configuration like: > >> > >> R (t=0) > >> / \ > >> D (t=1) > >> / \ > >> T D (t=1) > > Why not? > > > > First you create: > > > > R (t=0) > > / \ > > D (t=1) > > / \ > > T T (t=1) > > > > Then you flip t=0 like: > > > > R (t=0) > > / \ > > D (t=1) > > / \ > > T D (t=0) > > > > And then you flip t=1 again: > > > > R (t=0) > > / \ > > D (t=1) > > / \ > > T D (t=1) > > Tejun's thread mode patch has constraints on what operations are allowed > and what aren't. For a threaded subtree, thread mode cannot be disabled > in the middle of the tree.
Where in that scenario did I change anything in the middle? All operations were on a leaf group.
