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-rw-r--r--Documentation/cgroups/memory.txt16
1 files changed, 11 insertions, 5 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 1a608877b14..23d1262c077 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -152,14 +152,19 @@ When swap is accounted, following files are added.
usage of mem+swap is limited by memsw.limit_in_bytes.
-Note: why 'mem+swap' rather than swap.
+* why 'mem+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
-mem+swap.
+mem+swap. In other words, when we want to limit the usage of swap without
+affecting global LRU, mem+swap limit is better than just limiting swap from
+OS point of view.
-In other words, when we want to limit the usage of swap without affecting
-global LRU, mem+swap limit is better than just limiting swap from OS point
-of view.
+* What happens when a cgroup hits memory.memsw.limit_in_bytes
+When a cgroup his 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
+caches are dropped. But as mentioned above, global LRU can do swapout memory
+from it for sanity of the system's memory management state. You can't forbid
+it by cgroup.
2.5 Reclaim
@@ -204,6 +209,7 @@ We can alter the memory limit:
NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo,
mega or gigabytes.
+NOTE: We can write "-1" to reset the *.limit_in_bytes(unlimited).
# cat /cgroups/0/memory.limit_in_bytes
4194304