By using the memsw limit, you can avoid system OOM which can be caused by swap
shortage.
-**why 'memory+swap' rather than swap**
+2.4.1 why 'memory+swap' rather than swap
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The global LRU(kswapd) can swap out arbitrary pages. Swap-out means
to move account from memory to swap...there is no change in usage of
affecting global LRU, memory+swap limit is better than just limiting swap from
an OS point of view.
-**What happens when a cgroup hits memory.memsw.limit_in_bytes**
+2.4.2. What happens when a cgroup hits memory.memsw.limit_in_bytes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When a cgroup hits memory.memsw.limit_in_bytes, it's useless to do swap-out
in this cgroup. Then, swap-out will not be done by cgroup routine and file