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Documentation/memcg: warn about incomplete kmemcg state 

Kmemcg is currently under development and lacks some important features.
In particular, it does not have support of kmem reclaim on memory pressure
inside cgroup, which practically makes it unusable in real life.  Let's
warn about it in both Kconfig and Documentation to prevent complaints
arising.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vladimir Davydov 2014-06-04 16:07:28 -07:00 committed by Linus Torvalds
parent 613813e898
commit 2ee0646870
2 changed files with 11 additions and 0 deletions
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5
Documentation/cgroups/memory.txt
View File

@ -270,6 +270,11 @@ When oom event notifier is registered, event will be delivered.
2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM)
WARNING: Current implementation lacks reclaim support. That means allocation
attempts will fail when close to the limit even if there are plenty of
kmem available for reclaim. That makes this option unusable in real
life so DO NOT SELECT IT unless for development purposes.
With the Kernel memory extension, the Memory Controller is able to limit
the amount of kernel memory used by the system. Kernel memory is fundamentally
different than user memory, since it can't be swapped out, which makes it

6
init/Kconfig
View File

@ -996,6 +996,12 @@ config MEMCG_KMEM
the kmem extension can use it to guarantee that no group of processes
will ever exhaust kernel resources alone.
WARNING: Current implementation lacks reclaim support. That means
allocation attempts will fail when close to the limit even if there
are plenty of kmem available for reclaim. That makes this option
unusable in real life so DO NOT SELECT IT unless for development
purposes.
config CGROUP_HUGETLB
bool "HugeTLB Resource Controller for Control Groups"
depends on RESOURCE_COUNTERS && HUGETLB_PAGE