diff options
Diffstat (limited to 'Documentation/cgroups/memory.txt')
| -rw-r--r-- | Documentation/cgroups/memory.txt | 58 |
1 files changed, 39 insertions, 19 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 7c16347..06eb6d9 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -1,8 +1,8 @@ Memory Resource Controller -NOTE: The Memory Resource Controller has been generically been referred - to as the memory controller in this document. Do not confuse memory - controller used here with the memory controller that is used in hardware. +NOTE: The Memory Resource Controller has generically been referred to as the + memory controller in this document. Do not confuse memory controller + used here with the memory controller that is used in hardware. (For editors) In this document: @@ -70,6 +70,7 @@ Brief summary of control files. (See sysctl's vm.swappiness) memory.move_charge_at_immigrate # set/show controls of moving charges memory.oom_control # set/show oom controls. + memory.numa_stat # show the number of memory usage per numa node 1. History @@ -181,7 +182,7 @@ behind this approach is that a cgroup that aggressively uses a shared page will eventually get charged for it (once it is uncharged from the cgroup that brought it in -- this will happen on memory pressure). -Exception: If CONFIG_CGROUP_CGROUP_MEM_RES_CTLR_SWAP is not used.. +Exception: If CONFIG_CGROUP_CGROUP_MEM_RES_CTLR_SWAP is not used. When you do swapoff and make swapped-out pages of shmem(tmpfs) to be backed into memory in force, charges for pages are accounted against the caller of swapoff rather than the users of shmem. @@ -213,7 +214,7 @@ affecting global LRU, memory+swap limit is better than just limiting swap from OS point of view. * What happens when a cgroup hits memory.memsw.limit_in_bytes -When a cgroup his memory.memsw.limit_in_bytes, it's useless to do swap-out +When a cgroup hits memory.memsw.limit_in_bytes, it's useless to do swap-out in this cgroup. Then, swap-out will not be done by cgroup routine and file caches are dropped. But as mentioned above, global LRU can do swapout memory from it for sanity of the system's memory management state. You can't forbid @@ -263,16 +264,17 @@ b. Enable CONFIG_RESOURCE_COUNTERS c. Enable CONFIG_CGROUP_MEM_RES_CTLR d. Enable CONFIG_CGROUP_MEM_RES_CTLR_SWAP (to use swap extension) -1. Prepare the cgroups -# mkdir -p /cgroups -# mount -t cgroup none /cgroups -o memory +1. Prepare the cgroups (see cgroups.txt, Why are cgroups needed?) +# mount -t tmpfs none /sys/fs/cgroup +# mkdir /sys/fs/cgroup/memory +# mount -t cgroup none /sys/fs/cgroup/memory -o memory 2. Make the new group and move bash into it -# mkdir /cgroups/0 -# echo $$ > /cgroups/0/tasks +# mkdir /sys/fs/cgroup/memory/0 +# echo $$ > /sys/fs/cgroup/memory/0/tasks Since now we're in the 0 cgroup, we can alter the memory limit: -# echo 4M > /cgroups/0/memory.limit_in_bytes +# echo 4M > /sys/fs/cgroup/memory/0/memory.limit_in_bytes NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo, mega or gigabytes. (Here, Kilo, Mega, Giga are Kibibytes, Mebibytes, Gibibytes.) @@ -280,11 +282,11 @@ mega or gigabytes. (Here, Kilo, Mega, Giga are Kibibytes, Mebibytes, Gibibytes.) NOTE: We can write "-1" to reset the *.limit_in_bytes(unlimited). NOTE: We cannot set limits on the root cgroup any more. -# cat /cgroups/0/memory.limit_in_bytes +# cat /sys/fs/cgroup/memory/0/memory.limit_in_bytes 4194304 We can check the usage: -# cat /cgroups/0/memory.usage_in_bytes +# cat /sys/fs/cgroup/memory/0/memory.usage_in_bytes 1216512 A successful write to this file does not guarantee a successful set of @@ -464,6 +466,24 @@ value for efficient access. (Of course, when necessary, it's synchronized.) If you want to know more exact memory usage, you should use RSS+CACHE(+SWAP) value in memory.stat(see 5.2). +5.6 numa_stat + +This is similar to numa_maps but operates on a per-memcg basis. This is +useful for providing visibility into the numa locality information within +an memcg since the pages are allowed to be allocated from any physical +node. One of the usecases is evaluating application performance by +combining this information with the application's cpu allocation. + +We export "total", "file", "anon" and "unevictable" pages per-node for +each memcg. The ouput format of memory.numa_stat is: + +total=<total pages> N0=<node 0 pages> N1=<node 1 pages> ... +file=<total file pages> N0=<node 0 pages> N1=<node 1 pages> ... +anon=<total anon pages> N0=<node 0 pages> N1=<node 1 pages> ... +unevictable=<total anon pages> N0=<node 0 pages> N1=<node 1 pages> ... + +And we have total = file + anon + unevictable. + 6. Hierarchy support The memory controller supports a deep hierarchy and hierarchical accounting. @@ -471,13 +491,13 @@ The hierarchy is created by creating the appropriate cgroups in the cgroup filesystem. Consider for example, the following cgroup filesystem hierarchy - root + root / | \ - / | \ - a b c - | \ - | \ - d e + / | \ + a b c + | \ + | \ + d e In the diagram above, with hierarchical accounting enabled, all memory usage of e, is accounted to its ancestors up until the root (i.e, c and root), |
