conventions of cgroup v2. It describes all userland-visible aspects
of cgroup including core and specific controller behaviors. All
future changes must be reflected in this document. Documentation for
-v1 is available under Documentation/cgroup-legacy/.
+v1 is available under Documentation/cgroup-v1/.
CONTENTS
the cgroup. This may not exactly match the number of
processes killed but should generally be close.
+ memory.stat
+
+ A read-only flat-keyed file which exists on non-root cgroups.
+
+ This breaks down the cgroup's memory footprint into different
+ types of memory, type-specific details, and other information
+ on the state and past events of the memory management system.
+
+ All memory amounts are in bytes.
+
+ The entries are ordered to be human readable, and new entries
+ can show up in the middle. Don't rely on items remaining in a
+ fixed position; use the keys to look up specific values!
+
+ anon
+
+ Amount of memory used in anonymous mappings such as
+ brk(), sbrk(), and mmap(MAP_ANONYMOUS)
+
+ file
+
+ Amount of memory used to cache filesystem data,
+ including tmpfs and shared memory.
+
+ sock
+
+ Amount of memory used in network transmission buffers
+
+ file_mapped
+
+ Amount of cached filesystem data mapped with mmap()
+
+ file_dirty
+
+ Amount of cached filesystem data that was modified but
+ not yet written back to disk
+
+ file_writeback
+
+ Amount of cached filesystem data that was modified and
+ is currently being written back to disk
+
+ inactive_anon
+ active_anon
+ inactive_file
+ active_file
+ unevictable
+
+ Amount of memory, swap-backed and filesystem-backed,
+ on the internal memory management lists used by the
+ page reclaim algorithm
+
+ pgfault
+
+ Total number of page faults incurred
+
+ pgmajfault
+
+ Number of major page faults incurred
+
+ memory.swap.current
+
+ A read-only single value file which exists on non-root
+ cgroups.
+
+ The total amount of swap currently being used by the cgroup
+ and its descendants.
+
+ memory.swap.max
+
+ A read-write single value file which exists on non-root
+ cgroups. The default is "max".
+
+ Swap usage hard limit. If a cgroup's swap usage reaches this
+ limit, anonymous meomry of the cgroup will not be swapped out.
+
5-2-2. General Usage
system than killing the group. Otherwise, memory.max is there to
limit this type of spillover and ultimately contain buggy or even
malicious applications.
+
+The combined memory+swap accounting and limiting is replaced by real
+control over swap space.
+
+The main argument for a combined memory+swap facility in the original
+cgroup design was that global or parental pressure would always be
+able to swap all anonymous memory of a child group, regardless of the
+child's own (possibly untrusted) configuration. However, untrusted
+groups can sabotage swapping by other means - such as referencing its
+anonymous memory in a tight loop - and an admin can not assume full
+swappability when overcommitting untrusted jobs.
+
+For trusted jobs, on the other hand, a combined counter is not an
+intuitive userspace interface, and it flies in the face of the idea
+that cgroup controllers should account and limit specific physical
+resources. Swap space is a resource like all others in the system,
+and that's why unified hierarchy allows distributing it separately.