From 7de37682bec35bbe0cd69b8112ef257bc5fb1c3e Mon Sep 17 00:00:00 2001 From: Glauber Costa Date: Tue, 18 Dec 2012 14:22:07 -0800 Subject: [PATCH] memcg: kmem accounting lifecycle management Because kmem charges can outlive the cgroup, we need to make sure that we won't free the memcg structure while charges are still in flight. For reviewing simplicity, the charge functions will issue mem_cgroup_get() at every charge, and mem_cgroup_put() at every uncharge. This can get expensive, however, and we can do better. mem_cgroup_get() only really needs to be issued once: when the first limit is set. In the same spirit, we only need to issue mem_cgroup_put() when the last charge is gone. We'll need an extra bit in kmem_account_flags for that: KMEM_ACCOUNTED_DEAD. it will be set when the cgroup dies, if there are charges in the group. If there aren't, we can proceed right away. Our uncharge function will have to test that bit every time the charges drop to 0. Because that is not the likely output of res_counter_uncharge, this should not impose a big hit on us: it is certainly much better than a reference count decrease at every operation. Signed-off-by: Glauber Costa Acked-by: Michal Hocko Acked-by: Kamezawa Hiroyuki Cc: Christoph Lameter Cc: Pekka Enberg Cc: Johannes Weiner Cc: Suleiman Souhlal Cc: Tejun Heo Cc: David Rientjes Cc: Frederic Weisbecker Cc: Greg Thelen Cc: JoonSoo Kim Cc: Mel Gorman Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-format-patch failed