diff options
| author | Michal Hocko <mhocko@suse.cz> | 2014-05-22 10:54:35 +1000 |
|---|---|---|
| committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2014-05-27 18:24:32 +1000 |
| commit | 757df1a37b022058bca5982ee2bfd07899fc9ac4 (patch) | |
| tree | 94b8e94f043ede8a38e3ed0dcae73946415fb83e /Documentation | |
| parent | cdc614ab013afdc002b58e93765d43d20404f39c (diff) | |
memcg, doc: clarify global vs. limit reclaims
Be explicit about global and hard limit reclaims in our documentation.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/cgroups/memory.txt | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 2d70ceabadb7..5ba92acc0e25 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -236,23 +236,26 @@ it by cgroup. 2.5 Reclaim Each cgroup maintains a per cgroup LRU which has the same structure as -global VM. When a cgroup goes over its limit, we first try -to reclaim memory from the cgroup so as to make space for the new -pages that the cgroup has touched. If the reclaim is unsuccessful, -an OOM routine is invoked to select and kill the bulkiest task in the -cgroup. (See 10. OOM Control below.) - -The reclaim algorithm has not been modified for cgroups, except that -pages that are selected for reclaiming come from the per-cgroup LRU -list. - -NOTE: Reclaim does not work for the root cgroup, since we cannot set any -limits on the root cgroup. +global VM. Cgroups can get reclaimed basically under two conditions + - under global memory pressure when all cgroups are reclaimed + proportionally wrt. their LRU size in a round robin fashion + - when a cgroup or its hierarchical parent (see 6. Hierarchical support) + hits hard limit. If the reclaim is unsuccessful, an OOM routine is invoked + to select and kill the bulkiest task in the cgroup. (See 10. OOM Control + below.) + +Global and hard-limit reclaims share the same code the only difference +is the objective of the reclaim. The global reclaim aims at balancing +zones' watermarks while the limit reclaim frees some memory to allow new +charges. + +NOTE: Hard limit reclaim does not work for the root cgroup, since we cannot set +any limits on the root cgroup. Note2: When panic_on_oom is set to "2", the whole system will panic. -When oom event notifier is registered, event will be delivered. -(See oom_control section) +When oom event notifier is registered, event will be delivered to the root +of the memory pressure which cannot be handled (See oom_control section) 2.6 Locking |