diff options
Diffstat (limited to 'Documentation/cgroups/memory.txt')
| -rw-r--r-- | Documentation/cgroups/memory.txt | 37 |
1 files changed, 32 insertions, 5 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index cc0ebc5241b..4c95c0034a4 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -44,8 +44,8 @@ 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. + Kernel memory support is work in progress, and the current version provides + basically functionality. (See Section 2.7) Brief summary of control files. @@ -61,7 +61,7 @@ Brief summary of control files. 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 - memory.memsw.usage_in_bytes # show max memory+Swap usage recorded + memory.memsw.max_usage_in_bytes # show max memory+Swap usage recorded memory.soft_limit_in_bytes # set/show soft limit of memory usage memory.stat # show various statistics memory.use_hierarchy # set/show hierarchical account enabled @@ -72,6 +72,9 @@ 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.kmem.tcp.limit_in_bytes # set/show hard limit for tcp buf memory + memory.kmem.tcp.usage_in_bytes # show current tcp buf memory allocation + 1. History The memory controller has a long history. A request for comments for the memory @@ -255,6 +258,27 @@ 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. + +Kernel memory limits are not imposed for the root cgroup. Usage for the root +cgroup may or may not be accounted. + +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 + +* sockets memory pressure: some sockets protocols have memory pressure +thresholds. The Memory Controller allows them to be controlled individually +per cgroup, instead of globally. + +* tcp memory pressure: sockets memory pressure for the tcp protocol. + 3. User Interface 0. Configuration @@ -386,8 +410,11 @@ memory.stat file includes following statistics cache - # of bytes of page cache memory. rss - # of bytes of anonymous and swap cache memory. mapped_file - # of bytes of mapped file (includes tmpfs/shmem) -pgpgin - # of pages paged in (equivalent to # of charging events). -pgpgout - # of pages paged out (equivalent to # of uncharging events). +pgpgin - # of charging events to the memory cgroup. The charging + event happens each time a page is accounted as either mapped + anon page(RSS) or cache page(Page Cache) to the cgroup. +pgpgout - # of uncharging events to the memory cgroup. The uncharging + event happens each time a page is unaccounted from the cgroup. swap - # of bytes of swap usage inactive_anon - # of bytes of anonymous memory and swap cache memory on LRU list. |