Messages in this thread Patch in this message | | | Date | Thu, 14 Jul 2016 19:13:12 +0200 | From | Oleg Nesterov <> | Subject | Re: Severe performance regression w/ 4.4+ on Android due to cgroup locking changes |
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On 07/14, John Stultz wrote: > > So I am seeing synchronize_sched called, and its taking the > !rcu_gp_is_expedited path when I see the particularly bad latencies. > > I wonder if I just mucked up applying the patch?
Probably yes...
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); + get_user_ns(init_cgroup_ns.user_ns); mutex_lock(&cgroup_mutex);
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