On 07/20/2012 05:05 PM, Tejun Heo wrote: > Hey, Peter. > > On Fri, Jul 20, 2012 at 05:45:40PM +0200, Peter Zijlstra wrote: >>> So, Peter, why does cpuset mangle with cgroup_mutex? What guarantees >>> does it need? Why can't it work on "changed" notification while >>> caching the current css like blkcg does? >> >> I've no clue sorry.. /me goes stare at this stuff.. Looks like something >> Paul Menage did when he created cgroups. I'll have to have a hard look >> at all that to untangle this. Not something obvious to me. > > Yeah, it would be great if this can be untangled. I really don't see > any other reasonable way out of this circular locking mess. If cpuset > needs stable css association across certain period, the RTTD is > caching the css by holding its ref and synchronize modifications to > that cache, rather than synchronizing cgroup operations themselves. > > Thanks. > IIRC, cpuset can insert a task into an existing cgroup itself. Besides that, it needs go have a stable vision of the cpumask used by all tasks in the cgroup. But this is what I remember from the top of my head, and I am still officially on vacations.... -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>