Hello, Matt. On Thu, Aug 25, 2011 at 07:38:18PM -0700, Matt Helsley wrote: > On Fri, Aug 26, 2011 at 12:43:09AM +0200, Tejun Heo wrote: > > Currently, there's no way to pass multiple tasks to cgroup_subsys > > methods necessitating the need for separate per-process and per-task > > methods. This patch introduces cgroup_taskset which can be used to > > pass multiple tasks and their associated cgroups to cgroup_subsys > > methods. > > This will be the third iterator-ish pattern in the cgroup code. > It's not your fault but it does seem a bit much to have: ... > Is there a sane way to merge all this? If merging isn't complicated and simplifies the code and its users, definitely but I don't think that will be the case here. If there are different targets to iterate, having matching iterators isn't a weird thing after all. I personally am not too enthusiastic about mixing locking with iterator (the implied read_lock in the cgroup iterator) or iteration-by-callback but that's a different issue. > Perhaps we could drop the iterator interfaces in 1) and 2) and replace > it with: > > tset cgroup_taskset_from_cgroup(cgroup) > > which would grab the css set lock to construct the tset from the given > cgroup -- essentially inlining the current iterator code into a single > function. * It doesn't need to walk the whole cgroup. * It requires stable set of tasks (ie. atomicity w.r.t. the thread group) with sleepable context which is currently achieved by a rwsem in the task to protect against fork and getting an extra reference to the tasks in the set. I don't think widening the scope would achieve much (why do we want to pass in unrelated tasks to subsystems as a single bundle?) while introducing unnecessary scalability limitation (moving out a single process ends up being an operation on the whole cgroup). I don't see how it would be better but, if you do, please go ahead. Consolidating stuff is (almost) always a good idea. :) Thanks. -- tejun _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
