On 07/14, John Stultz wrote: > > I'm not supposed to be applying this on-top of > Paul's change, right?
Right, unless I am totally confused, > > Just in case, could you try the patch below? Of course, without other > > optimizations from Peter, this change makes cgroup_threadgroup_rwsem > > much worse than a plain rw_semaphore. > > > > Oleg. > > > > --- x/kernel/cgroup.c > > +++ x/kernel/cgroup.c > > @@ -5605,6 +5605,8 @@ int __init cgroup_init(void) > > BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); > > BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); > > > > + rcu_sync_enter(&cgroup_threadgroup_rwsem.rss); > > + > > > So adding this does make a huge difference ontop of Peter's patch. Ah, sorry for confusion. I meant, you could try this one-liner without any other changes. But we will need the "slow mode optimization" part from Peter's patch anyway, otherwise percpu_rw_semaphore simply makes no sense for cgroup_threadgroup_rwsem. Oleg.
