On 07/12/2017 03:45 AM, Peter Zijlstra wrote: > 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. What I mean is that you can't disable thread mode if not at the thread root with no children left. 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
