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Diffstat (limited to 'Documentation/cgroups/memory.txt')
| -rw-r--r-- | Documentation/cgroups/memory.txt | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index cc0ebc5241b3..f2453241142b 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -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 |