path: root/Documentation/cgroups
diff options
authorAnton Arapov <>2012-10-29 11:15:37 +0100
committerAnton Arapov <>2012-10-29 11:15:37 +0100
commit7d558cd9c7b18e4b16953265aa0da45e63f3b968 (patch)
tree7135d5a810768c9c619346282ee9cfdf1765e225 /Documentation/cgroups
parent985ef6b2108ed28ffd5f6630e1e0fce2e2a775f2 (diff)
fedora kernel: cd394142aac30b5c751f25b517572e2448695641v3.6.3-2f17
Signed-off-by: Anton Arapov <>
Diffstat (limited to 'Documentation/cgroups')
3 files changed, 59 insertions, 25 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 8e74980ab38..4a0b64c605f 100644
--- a/Documentation/cgroups/cgroups.txt
+++ b/Documentation/cgroups/cgroups.txt
@@ -370,15 +370,12 @@ To mount a cgroup hierarchy with just the cpuset and memory
subsystems, type:
# mount -t cgroup -o cpuset,memory hier1 /sys/fs/cgroup/rg1
-To change the set of subsystems bound to a mounted hierarchy, just
-remount with different options:
-# mount -o remount,cpuset,blkio hier1 /sys/fs/cgroup/rg1
-Now memory is removed from the hierarchy and blkio is added.
-Note this will add blkio to the hierarchy but won't remove memory or
-cpuset, because the new options are appended to the old ones:
-# mount -o remount,blkio /sys/fs/cgroup/rg1
+While remounting cgroups is currently supported, it is not recommend
+to use it. Remounting allows changing bound subsystems and
+release_agent. Rebinding is hardly useful as it only works when the
+hierarchy is empty and release_agent itself should be replaced with
+conventional fsnotify. The support for remounting will be removed in
+the future.
To Specify a hierarchy's release_agent:
# mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \
@@ -637,16 +634,6 @@ void exit(struct task_struct *task)
Called during task exit.
-int populate(struct cgroup *cgrp)
-(cgroup_mutex held by caller)
-Called after creation of a cgroup to allow a subsystem to populate
-the cgroup directory with file entries. The subsystem should make
-calls to cgroup_add_file() with objects of type cftype (see
-include/linux/cgroup.h for details). Note that although this
-method can return an error code, the error code is currently not
-always handled well.
void post_clone(struct cgroup *cgrp)
(cgroup_mutex held by caller)
@@ -656,7 +643,7 @@ example in cpusets, no task may attach before 'cpus' and 'mems' are set
void bind(struct cgroup *root)
-(cgroup_mutex and ss->hierarchy_mutex held by caller)
+(cgroup_mutex held by caller)
Called when a cgroup subsystem is rebound to a different hierarchy
and root cgroup. Currently this will only involve movement between
diff --git a/Documentation/cgroups/hugetlb.txt b/Documentation/cgroups/hugetlb.txt
new file mode 100644
index 00000000000..a9faaca1f02
--- /dev/null
+++ b/Documentation/cgroups/hugetlb.txt
@@ -0,0 +1,45 @@
+HugeTLB Controller
+The HugeTLB controller allows to limit the HugeTLB usage per control group and
+enforces the controller limit during page fault. Since HugeTLB doesn't
+support page reclaim, enforcing the limit at page fault time implies that,
+the application will get SIGBUS signal if it tries to access HugeTLB pages
+beyond its limit. This requires the application to know beforehand how much
+HugeTLB pages it would require for its use.
+HugeTLB controller can be created by first mounting the cgroup filesystem.
+# mount -t cgroup -o hugetlb none /sys/fs/cgroup
+With the above step, the initial or the parent HugeTLB group becomes
+visible at /sys/fs/cgroup. At bootup, this group includes all the tasks in
+the system. /sys/fs/cgroup/tasks lists the tasks in this cgroup.
+New groups can be created under the parent group /sys/fs/cgroup.
+# cd /sys/fs/cgroup
+# mkdir g1
+# echo $$ > g1/tasks
+The above steps create a new group g1 and move the current shell
+process (bash) into it.
+Brief summary of control files
+ hugetlb.<hugepagesize>.limit_in_bytes # set/show limit of "hugepagesize" hugetlb usage
+ hugetlb.<hugepagesize>.max_usage_in_bytes # show max "hugepagesize" hugetlb usage recorded
+ hugetlb.<hugepagesize>.usage_in_bytes # show current res_counter usage for "hugepagesize" hugetlb
+ hugetlb.<hugepagesize>.failcnt # show the number of allocation failure due to HugeTLB limit
+For a system supporting two hugepage size (16M and 16G) the control
+files include:
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index dd88540bb99..4372e6b8a35 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -73,6 +73,8 @@ Brief summary of control files.
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
+ memory.kmem.tcp.failcnt # show the number of tcp buf memory usage hits limits
+ memory.kmem.tcp.max_usage_in_bytes # show max tcp buf memory usage recorded
1. History
@@ -187,12 +189,12 @@ the cgroup that brought it in -- this will happen on memory pressure).
But see section 8.2: when moving a task to another cgroup, its pages may
be recharged to the new cgroup, if move_charge_at_immigrate has been chosen.
+Exception: If CONFIG_CGROUP_CGROUP_MEMCG_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.
+2.4 Swap Extension (CONFIG_MEMCG_SWAP)
Swap Extension allows you to record charge for swap. A swapped-in page is
charged back to original page allocator if possible.
@@ -259,7 +261,7 @@ 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)
+2.7 Kernel Memory Extension (CONFIG_MEMCG_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
@@ -286,8 +288,8 @@ per cgroup, instead of globally.
-d. Enable CONFIG_CGROUP_MEM_RES_CTLR_SWAP (to use swap extension)
+d. Enable CONFIG_MEMCG_SWAP (to use swap extension)
1. Prepare the cgroups (see cgroups.txt, Why are cgroups needed?)
# mount -t tmpfs none /sys/fs/cgroup