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-rw-r--r--Documentation/cgroups/cpuacct.txt18
-rw-r--r--Documentation/cgroups/memory.txt55
-rw-r--r--Documentation/cgroups/resource_counter.txt27
3 files changed, 71 insertions, 29 deletions
diff --git a/Documentation/cgroups/cpuacct.txt b/Documentation/cgroups/cpuacct.txt
index bb775fbe43d7..8b930946c52a 100644
--- a/Documentation/cgroups/cpuacct.txt
+++ b/Documentation/cgroups/cpuacct.txt
@@ -30,3 +30,21 @@ The above steps create a new group g1 and move the current shell
process (bash) into it. CPU time consumed by this bash and its children
can be obtained from g1/cpuacct.usage and the same is accumulated in
/cgroups/cpuacct.usage also.
+
+cpuacct.stat file lists a few statistics which further divide the
+CPU time obtained by the cgroup into user and system times. Currently
+the following statistics are supported:
+
+user: Time spent by tasks of the cgroup in user mode.
+system: Time spent by tasks of the cgroup in kernel mode.
+
+user and system are in USER_HZ unit.
+
+cpuacct controller uses percpu_counter interface to collect user and
+system times. This has two side effects:
+
+- It is theoretically possible to see wrong values for user and system times.
+ This is because percpu_counter_read() on 32bit systems isn't safe
+ against concurrent writes.
+- It is possible to see slightly outdated values for user and system times
+ due to the batch processing nature of percpu_counter.
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index a98a7fe7aabb..1a608877b14e 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -6,15 +6,14 @@ used here with the memory controller that is used in hardware.
Salient features
-a. Enable control of both RSS (mapped) and Page Cache (unmapped) pages
+a. Enable control of Anonymous, Page Cache (mapped and unmapped) and
+ Swap Cache memory pages.
b. The infrastructure allows easy addition of other types of memory to control
c. Provides *zero overhead* for non memory controller users
d. Provides a double LRU: global memory pressure causes reclaim from the
global LRU; a cgroup on hitting a limit, reclaims from the per
cgroup LRU
-NOTE: Swap Cache (unmapped) is not accounted now.
-
Benefits and Purpose of the memory controller
The memory controller isolates the memory behaviour of a group of tasks
@@ -290,34 +289,44 @@ will be charged as a new owner of it.
moved to the parent. If you want to avoid that, force_empty will be useful.
5.2 stat file
- memory.stat file includes following statistics (now)
- cache - # of pages from page-cache and shmem.
- rss - # of pages from anonymous memory.
- pgpgin - # of event of charging
- pgpgout - # of event of uncharging
- active_anon - # of pages on active lru of anon, shmem.
- inactive_anon - # of pages on active lru of anon, shmem
- active_file - # of pages on active lru of file-cache
- inactive_file - # of pages on inactive lru of file cache
- unevictable - # of pages cannot be reclaimed.(mlocked etc)
-
- Below is depend on CONFIG_DEBUG_VM.
- inactive_ratio - VM internal parameter. (see mm/page_alloc.c)
- recent_rotated_anon - VM internal parameter. (see mm/vmscan.c)
- recent_rotated_file - VM internal parameter. (see mm/vmscan.c)
- recent_scanned_anon - VM internal parameter. (see mm/vmscan.c)
- recent_scanned_file - VM internal parameter. (see mm/vmscan.c)
-
- Memo:
+
+memory.stat file includes following statistics
+
+cache - # of bytes of page cache memory.
+rss - # of bytes of anonymous and swap cache memory.
+pgpgin - # of pages paged in (equivalent to # of charging events).
+pgpgout - # of pages paged out (equivalent to # of uncharging events).
+active_anon - # of bytes of anonymous and swap cache memory on active
+ lru list.
+inactive_anon - # of bytes of anonymous memory and swap cache memory on
+ inactive lru list.
+active_file - # of bytes of file-backed memory on active lru list.
+inactive_file - # of bytes of file-backed memory on inactive lru list.
+unevictable - # of bytes of memory that cannot be reclaimed (mlocked etc).
+
+The following additional stats are dependent on CONFIG_DEBUG_VM.
+
+inactive_ratio - VM internal parameter. (see mm/page_alloc.c)
+recent_rotated_anon - VM internal parameter. (see mm/vmscan.c)
+recent_rotated_file - VM internal parameter. (see mm/vmscan.c)
+recent_scanned_anon - VM internal parameter. (see mm/vmscan.c)
+recent_scanned_file - VM internal parameter. (see mm/vmscan.c)
+
+Memo:
recent_rotated means recent frequency of lru rotation.
recent_scanned means recent # of scans to lru.
showing for better debug please see the code for meanings.
+Note:
+ Only anonymous and swap cache memory is listed as part of 'rss' stat.
+ This should not be confused with the true 'resident set size' or the
+ amount of physical memory used by the cgroup. Per-cgroup rss
+ accounting is not done yet.
5.3 swappiness
Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
- Following cgroup's swapiness can't be changed.
+ Following cgroups' swapiness can't be changed.
- root cgroup (uses /proc/sys/vm/swappiness).
- a cgroup which uses hierarchy and it has child cgroup.
- a cgroup which uses hierarchy and not the root of hierarchy.
diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
index f196ac1d7d25..95b24d766eab 100644
--- a/Documentation/cgroups/resource_counter.txt
+++ b/Documentation/cgroups/resource_counter.txt
@@ -47,13 +47,18 @@ to work with it.
2. Basic accounting routines
- a. void res_counter_init(struct res_counter *rc)
+ a. void res_counter_init(struct res_counter *rc,
+ struct res_counter *rc_parent)
Initializes the resource counter. As usual, should be the first
routine called for a new counter.
- b. int res_counter_charge[_locked]
- (struct res_counter *rc, unsigned long val)
+ The struct res_counter *parent can be used to define a hierarchical
+ child -> parent relationship directly in the res_counter structure,
+ NULL can be used to define no relationship.
+
+ c. int res_counter_charge(struct res_counter *rc, unsigned long val,
+ struct res_counter **limit_fail_at)
When a resource is about to be allocated it has to be accounted
with the appropriate resource counter (controller should determine
@@ -67,15 +72,25 @@ to work with it.
* if the charging is performed first, then it should be uncharged
on error path (if the one is called).
- c. void res_counter_uncharge[_locked]
+ If the charging fails and a hierarchical dependency exists, the
+ limit_fail_at parameter is set to the particular res_counter element
+ where the charging failed.
+
+ d. int res_counter_charge_locked
+ (struct res_counter *rc, unsigned long val)
+
+ The same as res_counter_charge(), but it must not acquire/release the
+ res_counter->lock internally (it must be called with res_counter->lock
+ held).
+
+ e. void res_counter_uncharge[_locked]
(struct res_counter *rc, unsigned long val)
When a resource is released (freed) it should be de-accounted
from the resource counter it was accounted to. This is called
"uncharging".
- The _locked routines imply that the res_counter->lock is taken.
-
+ The _locked routines imply that the res_counter->lock is taken.
2.1 Other accounting routines