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Basic kernel memory functionality for the Memory Controller

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This patch lays down the foundation for the kernel memory component
of the Memory Controller.

As of today, I am only laying down the following files:

 * memory.independent_kmem_limit
 * memory.kmem.limit_in_bytes (currently ignored)
 * memory.kmem.usage_in_bytes (always zero)

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Kirill A. Shutemov <kirill@shutemov.name>
CC: Paul Menage <paul@paulmenage.org>
CC: Greg Thelen <gthelen@google.com>
CC: Johannes Weiner <jweiner@redhat.com>
CC: Michal Hocko <mhocko@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Glauber Costa
2011-12-11 21:47:01 +00:00
committed by David S. Miller
parent 08e34eb14f
commit e5671dfae5
3 changed files with 149 additions and 7 deletions
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40
Documentation/cgroups/memory.txt
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@@ -44,8 +44,9 @@ Features:
- oom-killer disable knob and oom-notifier
- Root cgroup has no limit controls.
Kernel memory and Hugepages are not under control yet. We just manage
pages on LRU. To add more controls, we have to take care of performance.
Hugepages is not under control yet. We just manage pages on LRU. To add more
controls, we have to take care of performance. Kernel memory support is work
in progress, and the current version provides basically functionality.
Brief summary of control files.
@@ -56,8 +57,11 @@ Brief summary of control files.
(See 5.5 for details)
memory.memsw.usage_in_bytes # show current res_counter usage for memory+Swap
(See 5.5 for details)
memory.kmem.usage_in_bytes # show current res_counter usage for kmem only.
(See 2.7 for details)
memory.limit_in_bytes # set/show limit of memory usage
memory.memsw.limit_in_bytes # set/show limit of memory+Swap usage
memory.kmem.limit_in_bytes # if allowed, set/show limit of kernel memory
memory.failcnt # show the number of memory usage hits limits
memory.memsw.failcnt # show the number of memory+Swap hits limits
memory.max_usage_in_bytes # show max memory usage recorded
@@ -72,6 +76,9 @@ Brief summary of control files.
memory.oom_control # set/show oom controls.
memory.numa_stat # show the number of memory usage per numa node
memory.independent_kmem_limit # select whether or not kernel memory limits are
independent of user limits
1. History
The memory controller has a long history. A request for comments for the memory
@@ -255,6 +262,35 @@ When oom event notifier is registered, event will be delivered.
per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by
zone->lru_lock, it has no lock of its own.
2.7 Kernel Memory Extension (CONFIG_CGROUP_MEM_RES_CTLR_KMEM)
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
possible to DoS the system by consuming too much of this precious resource.
Some kernel memory resources may be accounted and limited separately from the
main "kmem" resource. For instance, a slab cache that is considered important
enough to be limited separately may have its own knobs.
Kernel memory limits are not imposed for the root cgroup. Usage for the root
cgroup may or may not be accounted.
Memory limits as specified by the standard Memory Controller may or may not
take kernel memory into consideration. This is achieved through the file
memory.independent_kmem_limit. A Value different than 0 will allow for kernel
memory to be controlled separately.
When kernel memory limits are not independent, the limit values set in
memory.kmem files are ignored.
Currently no soft limit is implemented for kernel memory. It is future work
to trigger slab reclaim when those limits are reached.
2.7.1 Current Kernel Memory resources accounted
None
3. User Interface
0. Configuration