On Tue, Aug 4, 2009 at 2:48 PM, Paul Menage<[email protected]> wrote: > On Mon, Aug 3, 2009 at 12:45 PM, Serge E. Hallyn<[email protected]> wrote: >> >> This is probably a stupid idea, but... what about having zero >> overhead at clone(), and instead, at cgroup_task_migrate(), >> dequeue_task()ing all of the affected threads for the duration of >> the migrate? >> > > Or a simpler alternative - rather than taking the thread group > leader's rwsem in cgroup_fork(), always take current's rwsem. Then > you're always locking a (probably?) local rwsem and minimizing the > overhead. So not quite zero overhead in the fork path, but I'd be > surprised if it was measurable. In cgroup_attach_proc() you then have > to take the rwsem of every thread in the process. Kind of the > equivalent of a per-threadgroup big-reader lock.
Hmm, the tasklist_lock section in fork() is entirely inside the read-lock. Presumably then iterating the threadgroup list to take all rwsems is safe from a race in which one thread escapes? _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
