On Thu, Apr 07, 2016 at 05:28:24AM -0400, Johannes Weiner wrote: > Hm? The root group can always contain tasks. It's not the only thing > the root is exempt from, it can't control any resources either:
it does in fact control resouces; the hierarchy directly affects the proportional distribution of time. > sched_group_set_shares(): > > /* > * We can't change the weight of the root cgroup. > */ > if (!tg->se[0]) > return -EINVAL; The root has, per definition, no siblings, so setting a weight is entirely pointless. > tg_set_cfs_bandwidth(): > > if (tg == &root_task_group) > return -EINVAL; > We have had patches to implement this, but have so far held off because they add a bunch of cycles to some really hot paths and we'd rather not do that. Its not impossible, or unthinkable to do this otherwise.
