Lines Matching +full:memory +full:- +full:controller
1 .. _cgroup-v2:
11 conventions of cgroup v2. It describes all userland-visible aspects
12 of cgroup including core and specific controller behaviors. All
14 v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgroup-v1>`.
19 1-1. Terminology
20 1-2. What is cgroup?
22 2-1. Mounting
23 2-2. Organizing Processes and Threads
24 2-2-1. Processes
25 2-2-2. Threads
26 2-3. [Un]populated Notification
27 2-4. Controlling Controllers
28 2-4-1. Enabling and Disabling
29 2-4-2. Top-down Constraint
30 2-4-3. No Internal Process Constraint
31 2-5. Delegation
32 2-5-1. Model of Delegation
33 2-5-2. Delegation Containment
34 2-6. Guidelines
35 2-6-1. Organize Once and Control
36 2-6-2. Avoid Name Collisions
38 3-1. Weights
39 3-2. Limits
40 3-3. Protections
41 3-4. Allocations
43 4-1. Format
44 4-2. Conventions
45 4-3. Core Interface Files
47 5-1. CPU
48 5-1-1. CPU Interface Files
49 5-2. Memory
50 5-2-1. Memory Interface Files
51 5-2-2. Usage Guidelines
52 5-2-3. Memory Ownership
53 5-3. IO
54 5-3-1. IO Interface Files
55 5-3-2. Writeback
56 5-3-3. IO Latency
57 5-3-3-1. How IO Latency Throttling Works
58 5-3-3-2. IO Latency Interface Files
59 5-3-4. IO Priority
60 5-4. PID
61 5-4-1. PID Interface Files
62 5-5. Cpuset
63 5.5-1. Cpuset Interface Files
64 5-6. Device
65 5-7. RDMA
66 5-7-1. RDMA Interface Files
67 5-8. HugeTLB
68 5.8-1. HugeTLB Interface Files
69 5-9. Misc
70 5.9-1 Miscellaneous cgroup Interface Files
71 5.9-2 Migration and Ownership
72 5-10. Others
73 5-10-1. perf_event
74 5-N. Non-normative information
75 5-N-1. CPU controller root cgroup process behaviour
76 5-N-2. IO controller root cgroup process behaviour
78 6-1. Basics
79 6-2. The Root and Views
80 6-3. Migration and setns(2)
81 6-4. Interaction with Other Namespaces
83 P-1. Filesystem Support for Writeback
86 R-1. Multiple Hierarchies
87 R-2. Thread Granularity
88 R-3. Competition Between Inner Nodes and Threads
89 R-4. Other Interface Issues
90 R-5. Controller Issues and Remedies
91 R-5-1. Memory
98 -----------
107 ---------------
113 cgroup is largely composed of two parts - the core and controllers.
115 processes. A cgroup controller is usually responsible for
128 disabled selectively on a cgroup. All controller behaviors are
129 hierarchical - if a controller is enabled on a cgroup, it affects all
131 sub-hierarchy of the cgroup. When a controller is enabled on a nested
141 --------
146 # mount -t cgroup2 none $MOUNT_POINT
155 A controller can be moved across hierarchies only after the controller
156 is no longer referenced in its current hierarchy. Because per-cgroup
157 controller states are destroyed asynchronously and controllers may
158 have lingering references, a controller may not show up immediately on
160 Similarly, a controller should be fully disabled to be moved out of
162 controller to become available for other hierarchies; furthermore, due
163 to inter-controller dependencies, other controllers may need to be
169 the hierarchies and controller associations before starting using the
184 ignored on non-init namespace mounts. Please refer to the
189 task migrations and controller on/offs at the cost of making
196 Only populate memory.events with data for the current cgroup,
201 option is ignored on non-init namespace mounts.
204 Recursively apply memory.min and memory.low protection to
209 behavior but is a mount-option to avoid regressing setups
214 Count HugeTLB memory usage towards the cgroup's overall
215 memory usage for the memory controller (for the purpose of
216 statistics reporting and memory protetion). This is a new
222 * There is no HugeTLB pool management involved in the memory
223 controller. The pre-allocated pool does not belong to anyone.
226 memory controller. It is only charged to a cgroup when it is
227 actually used (for e.g at page fault time). Host memory
230 done via other mechanisms (such as the HugeTLB controller).
231 * Failure to charge a HugeTLB folio to the memory controller
235 * Charging HugeTLB memory towards the memory controller affects
236 memory protection and reclaim dynamics. Any userspace tuning
239 will not be tracked by the memory controller (even if cgroup
244 --------------------------------
250 A child cgroup can be created by creating a sub-directory::
255 structure. Each cgroup has a read-writable interface file
257 belong to the cgroup one-per-line. The PIDs are not ordered and the
288 0::/test-cgroup/test-cgroup-nested
295 0::/test-cgroup/test-cgroup-nested (deleted)
321 constraint - threaded controllers can be enabled on non-leaf cgroups
345 - As the cgroup will join the parent's resource domain. The parent
348 - When the parent is an unthreaded domain, it must not have any domain
352 Topology-wise, a cgroup can be in an invalid state. Please consider
355 A (threaded domain) - B (threaded) - C (domain, just created)
370 threads in the cgroup. Except that the operations are per-thread
371 instead of per-process, "cgroup.threads" has the same format and
386 a threaded controller is enabled inside a threaded subtree, it only
392 constraint, a threaded controller must be able to handle competition
393 between threads in a non-leaf cgroup and its child cgroups. Each
394 threaded controller defines how such competitions are handled.
399 - cpu
400 - cpuset
401 - perf_event
402 - pids
405 --------------------------
407 Each non-root cgroup has a "cgroup.events" file which contains
408 "populated" field indicating whether the cgroup's sub-hierarchy has
412 example, to start a clean-up operation after all processes of a given
413 sub-hierarchy have exited. The populated state updates and
414 notifications are recursive. Consider the following sub-hierarchy
418 A(4) - B(0) - C(1)
428 -----------------------
437 cpu io memory
439 No controller is enabled by default. Controllers can be enabled and
442 # echo "+cpu +memory -io" > cgroup.subtree_control
446 all succeed or fail. If multiple operations on the same controller
449 Enabling a controller in a cgroup indicates that the distribution of
451 Consider the following sub-hierarchy. The enabled controllers are
454 A(cpu,memory) - B(memory) - C()
457 As A has "cpu" and "memory" enabled, A will control the distribution
458 of CPU cycles and memory to its children, in this case, B. As B has
459 "memory" enabled but not "CPU", C and D will compete freely on CPU
460 cycles but their division of memory available to B will be controlled.
462 As a controller regulates the distribution of the target resource to
463 the cgroup's children, enabling it creates the controller's interface
465 would create the "cpu." prefixed controller interface files in C and
466 D. Likewise, disabling "memory" from B would remove the "memory."
467 prefixed controller interface files from C and D. This means that the
468 controller interface files - anything which doesn't start with
472 Top-down Constraint
475 Resources are distributed top-down and a cgroup can further distribute
477 parent. This means that all non-root "cgroup.subtree_control" files
479 "cgroup.subtree_control" file. A controller can be enabled only if
480 the parent has the controller enabled and a controller can't be
487 Non-root cgroups can distribute domain resources to their children
492 This guarantees that, when a domain controller is looking at the part
501 is up to each controller (for more information on this topic please
502 refer to the Non-normative information section in the Controllers
506 enabled controller in the cgroup's "cgroup.subtree_control". This is
515 ----------
535 delegated, the user can build sub-hierarchy under the directory,
539 happens in the delegated sub-hierarchy, nothing can escape the
543 cgroups in or nesting depth of a delegated sub-hierarchy; however,
550 A delegated sub-hierarchy is contained in the sense that processes
551 can't be moved into or out of the sub-hierarchy by the delegatee.
554 requiring the following conditions for a process with a non-root euid
558 - The writer must have write access to the "cgroup.procs" file.
560 - The writer must have write access to the "cgroup.procs" file of the
564 processes around freely in the delegated sub-hierarchy it can't pull
565 in from or push out to outside the sub-hierarchy.
571 ~~~~~~~~~~~~~ - C0 - C00
574 ~~~~~~~~~~~~~ - C1 - C10
581 will be denied with -EACCES.
586 is not reachable, the migration is rejected with -ENOENT.
590 ----------
596 and stateful resources such as memory are not moved together with the
598 inherent trade-offs between migration and various hot paths in terms
604 resource structure once on start-up. Dynamic adjustments to resource
605 distribution can be made by changing controller configuration through
617 controller's interface files are prefixed with the controller name and
618 a dot. A controller's name is composed of lower case alphabets and
637 -------
643 work-conserving. Due to the dynamic nature, this model is usually
658 .. _cgroupv2-limits-distributor:
661 ------
664 Limits can be over-committed - the sum of the limits of children can
669 As limits can be over-committed, all configuration combinations are
676 .. _cgroupv2-protections-distributor:
679 -----------
684 soft boundaries. Protections can also be over-committed in which case
691 As protections can be over-committed, all configuration combinations
695 "memory.low" implements best-effort memory protection and is an
700 -----------
703 resource. Allocations can't be over-committed - the sum of the
710 As allocations can't be over-committed, some configuration
715 "cpu.rt.max" hard-allocates realtime slices and is an example of this
723 ------
728 New-line separated values
736 (when read-only or multiple values can be written at once)
762 -----------
764 - Settings for a single feature should be contained in a single file.
766 - The root cgroup should be exempt from resource control and thus
769 - The default time unit is microseconds. If a different unit is ever
772 - A parts-per quantity should use a percentage decimal with at least
773 two digit fractional part - e.g. 13.40.
775 - If a controller implements weight based resource distribution, its
781 - If a controller implements an absolute resource guarantee and/or
783 respectively. If a controller implements best effort resource
790 - If a setting has a configurable default value and keyed specific
804 # cat cgroup-example-interface-file
810 # echo 125 > cgroup-example-interface-file
814 # echo "default 125" > cgroup-example-interface-file
818 # echo "8:16 170" > cgroup-example-interface-file
822 # echo "8:0 default" > cgroup-example-interface-file
823 # cat cgroup-example-interface-file
827 - For events which are not very high frequency, an interface file
834 --------------------
839 A read-write single value file which exists on non-root
845 - "domain" : A normal valid domain cgroup.
847 - "domain threaded" : A threaded domain cgroup which is
850 - "domain invalid" : A cgroup which is in an invalid state.
854 - "threaded" : A threaded cgroup which is a member of a
861 A read-write new-line separated values file which exists on
865 the cgroup one-per-line. The PIDs are not ordered and the
874 - It must have write access to the "cgroup.procs" file.
876 - It must have write access to the "cgroup.procs" file of the
879 When delegating a sub-hierarchy, write access to this file
887 A read-write new-line separated values file which exists on
891 the cgroup one-per-line. The TIDs are not ordered and the
900 - It must have write access to the "cgroup.threads" file.
902 - The cgroup that the thread is currently in must be in the
905 - It must have write access to the "cgroup.procs" file of the
908 When delegating a sub-hierarchy, write access to this file
912 A read-only space separated values file which exists on all
919 A read-write space separated values file which exists on all
926 Space separated list of controllers prefixed with '+' or '-'
927 can be written to enable or disable controllers. A controller
928 name prefixed with '+' enables the controller and '-'
929 disables. If a controller appears more than once on the list,
934 A read-only flat-keyed file which exists on non-root cgroups.
946 A read-write single value files. The default is "max".
953 A read-write single value files. The default is "max".
960 A read-only flat-keyed file with the following entries:
978 A read-write single value file which exists on non-root cgroups.
1001 create new sub-cgroups.
1004 A write-only single value file which exists in non-root cgroups.
1016 the whole thread-group.
1019 A read-write single value file that allowed values are "0" and "1".
1023 Writing "1" to the file will re-enable the cgroup PSI accounting.
1031 This may cause non-negligible overhead for some workloads when under
1033 be used to disable PSI accounting in the non-leaf cgroups.
1036 A read-write nested-keyed file.
1044 .. _cgroup-v2-cpu:
1047 ---
1050 controller implements weight and absolute bandwidth limit models for
1062 the cpu controller can only be enabled when all RT processes are in
1066 before the cpu controller can be enabled.
1075 A read-only flat-keyed file.
1076 This file exists whether the controller is enabled or not.
1080 - usage_usec
1081 - user_usec
1082 - system_usec
1084 and the following five when the controller is enabled:
1086 - nr_periods
1087 - nr_throttled
1088 - throttled_usec
1089 - nr_bursts
1090 - burst_usec
1093 A read-write single value file which exists on non-root
1103 A read-write single value file which exists on non-root
1106 The nice value is in the range [-20, 19].
1115 A read-write two value file which exists on non-root cgroups.
1127 A read-write single value file which exists on non-root
1133 A read-write nested-keyed file.
1139 A read-write single value file which exists on non-root cgroups.
1154 A read-write single value file which exists on non-root cgroups.
1165 A read-write single value file which exists on non-root cgroups.
1168 This is the cgroup analog of the per-task SCHED_IDLE sched policy.
1176 Memory section in Controllers
1177 ------
1179 The "memory" controller regulates distribution of memory. Memory is
1181 intertwining between memory usage and reclaim pressure and the
1182 stateful nature of memory, the distribution model is relatively
1185 While not completely water-tight, all major memory usages by a given
1186 cgroup are tracked so that the total memory consumption can be
1188 following types of memory usages are tracked.
1190 - Userland memory - page cache and anonymous memory.
1192 - Kernel data structures such as dentries and inodes.
1194 - TCP socket buffers.
1199 Memory Interface Files argument
1202 All memory amounts are in bytes. If a value which is not aligned to
1206 memory.current
1207 A read-only single value file which exists on non-root
1210 The total amount of memory currently being used by the cgroup
1213 memory.min
1214 A read-write single value file which exists on non-root
1217 Hard memory protection. If the memory usage of a cgroup
1218 is within its effective min boundary, the cgroup's memory
1220 unprotected reclaimable memory available, OOM killer
1226 Effective min boundary is limited by memory.min values of
1227 all ancestor cgroups. If there is memory.min overcommitment
1228 (child cgroup or cgroups are requiring more protected memory
1231 actual memory usage below memory.min.
1233 Putting more memory than generally available under this
1236 If a memory cgroup is not populated with processes,
1237 its memory.min is ignored.
1239 memory.low
1240 A read-write single value file which exists on non-root
1243 Best-effort memory protection. If the memory usage of a
1245 memory won't be reclaimed unless there is no reclaimable
1246 memory available in unprotected cgroups.
1252 Effective low boundary is limited by memory.low values of
1253 all ancestor cgroups. If there is memory.low overcommitment
1254 (child cgroup or cgroups are requiring more protected memory
1257 actual memory usage below memory.low.
1259 Putting more memory than generally available under this
1262 memory.high
1263 A read-write single value file which exists on non-root
1266 Memory usage throttle limit. If a cgroup's usage goes
1276 memory.max
1277 A read-write single value file which exists on non-root
1280 Memory usage hard limit. This is the main mechanism to limit
1281 memory usage of a cgroup. If a cgroup's memory usage reaches
1286 In default configuration regular 0-order allocations always
1291 as -ENOMEM or silently ignore in cases like disk readahead.
1293 memory.reclaim
1294 A write-only nested-keyed file which exists for all cgroups.
1296 This is a simple interface to trigger memory reclaim in the
1304 echo "1G" > memory.reclaim
1308 type of memory to reclaim from (anon, file, ..).
1312 specified amount, -EAGAIN is returned.
1315 interface) is not meant to indicate memory pressure on the
1316 memory cgroup. Therefore socket memory balancing triggered by
1317 the memory reclaim normally is not exercised in this case.
1319 reclaim induced by memory.reclaim.
1321 memory.peak
1322 A read-only single value file which exists on non-root
1325 The max memory usage recorded for the cgroup and its
1328 memory.oom.group
1329 A read-write single value file which exists on non-root
1335 (if the memory cgroup is not a leaf cgroup) are killed
1339 Tasks with the OOM protection (oom_score_adj set to -1000)
1344 memory.oom.group values of ancestor cgroups.
1346 memory.events
1347 A read-only flat-keyed file which exists on non-root cgroups.
1355 memory.events.local.
1359 high memory pressure even though its usage is under
1361 boundary is over-committed.
1365 throttled and routed to perform direct memory reclaim
1366 because the high memory boundary was exceeded. For a
1367 cgroup whose memory usage is capped by the high limit
1368 rather than global memory pressure, this event's
1372 The number of times the cgroup's memory usage was
1377 The number of time the cgroup's memory usage was
1381 considered as an option, e.g. for failed high-order
1391 memory.events.local
1392 Similar to memory.events but the fields in the file are local
1396 memory.stat
1397 A read-only flat-keyed file which exists on non-root cgroups.
1399 This breaks down the cgroup's memory footprint into different
1400 types of memory, type-specific details, and other information
1401 on the state and past events of the memory management system.
1403 All memory amounts are in bytes.
1409 If the entry has no per-node counter (or not show in the
1410 memory.numa_stat). We use 'npn' (non-per-node) as the tag
1411 to indicate that it will not show in the memory.numa_stat.
1414 Amount of memory used in anonymous mappings such as
1418 Amount of memory used to cache filesystem data,
1419 including tmpfs and shared memory.
1422 Amount of total kernel memory, including
1424 addition to other kernel memory use cases.
1427 Amount of memory allocated to kernel stacks.
1430 Amount of memory allocated for page tables.
1433 Amount of memory allocated for secondary page tables,
1438 Amount of memory used for storing per-cpu kernel
1442 Amount of memory used in network transmission buffers
1445 Amount of memory used for vmap backed memory.
1448 Amount of cached filesystem data that is swap-backed,
1452 Amount of memory consumed by the zswap compression backend.
1455 Amount of application memory swapped out to zswap.
1469 Amount of swap cached in memory. The swapcache is accounted
1470 against both memory and swap usage.
1473 Amount of memory used in anonymous mappings backed by
1485 Amount of memory, swap-backed and filesystem-backed,
1486 on the internal memory management lists used by the
1490 memory management lists), inactive_foo + active_foo may not be equal to
1491 the value for the foo counter, since the foo counter is type-based, not
1492 list-based.
1499 Part of "slab" that cannot be reclaimed on memory
1503 Amount of memory used for storing in-kernel data
1570 Amount of pages postponed to be freed under memory pressure
1594 memory.numa_stat
1595 A read-only nested-keyed file which exists on non-root cgroups.
1597 This breaks down the cgroup's memory footprint into different
1598 types of memory, type-specific details, and other information
1599 per node on the state of the memory management system.
1607 All memory amounts are in bytes.
1609 The output format of memory.numa_stat is::
1617 The entries can refer to the memory.stat.
1619 memory.swap.current
1620 A read-only single value file which exists on non-root
1626 memory.swap.high
1627 A read-write single value file which exists on non-root
1632 allow userspace to implement custom out-of-memory procedures.
1636 during regular operation. Compare to memory.swap.max, which
1638 continue unimpeded as long as other memory can be reclaimed.
1642 memory.swap.peak
1643 A read-only single value file which exists on non-root
1649 memory.swap.max
1650 A read-write single value file which exists on non-root
1654 limit, anonymous memory of the cgroup will not be swapped out.
1656 memory.swap.events
1657 A read-only flat-keyed file which exists on non-root cgroups.
1673 because of running out of swap system-wide or max
1679 reduces the impact on the workload and memory management.
1681 memory.zswap.current
1682 A read-only single value file which exists on non-root
1685 The total amount of memory consumed by the zswap compression
1688 memory.zswap.max
1689 A read-write single value file which exists on non-root
1696 memory.zswap.writeback
1697 A read-write single value file. The default value is "1". The
1708 Note that this is subtly different from setting memory.swap.max to
1711 memory.pressure
1712 A read-only nested-keyed file.
1714 Shows pressure stall information for memory. See
1721 "memory.high" is the main mechanism to control memory usage.
1722 Over-committing on high limit (sum of high limits > available memory)
1723 and letting global memory pressure to distribute memory according to
1729 more memory or terminating the workload.
1731 Determining whether a cgroup has enough memory is not trivial as
1732 memory usage doesn't indicate whether the workload can benefit from
1733 more memory. For example, a workload which writes data received from
1734 network to a file can use all available memory but can also operate as
1735 performant with a small amount of memory. A measure of memory
1736 pressure - how much the workload is being impacted due to lack of
1737 memory - is necessary to determine whether a workload needs more
1738 memory; unfortunately, memory pressure monitoring mechanism isn't
1742 Memory Ownership argument
1745 A memory area is charged to the cgroup which instantiated it and stays
1747 to a different cgroup doesn't move the memory usages that it
1750 A memory area may be used by processes belonging to different cgroups.
1751 To which cgroup the area will be charged is in-deterministic; however,
1752 over time, the memory area is likely to end up in a cgroup which has
1753 enough memory allowance to avoid high reclaim pressure.
1755 If a cgroup sweeps a considerable amount of memory which is expected
1757 POSIX_FADV_DONTNEED to relinquish the ownership of memory areas
1758 belonging to the affected files to ensure correct memory ownership.
1762 --
1764 The "io" controller regulates the distribution of IO resources. This
1765 controller implements both weight based and absolute bandwidth or IOPS
1767 only if cfq-iosched is in use and neither scheme is available for
1768 blk-mq devices.
1775 A read-only nested-keyed file.
1795 A read-write nested-keyed file which exists only on the root
1799 model based controller (CONFIG_BLK_CGROUP_IOCOST) which
1807 enable Weight-based control enable
1817 The controller is disabled by default and can be enabled by
1819 to zero and the controller uses internal device saturation
1827 shows that on sdb, the controller is enabled, will consider
1839 devices which show wide temporary behavior changes - e.g. a
1850 A read-write nested-keyed file which exists only on the root
1854 controller (CONFIG_BLK_CGROUP_IOCOST) which currently
1863 model The cost model in use - "linear"
1889 generate device-specific coefficients.
1892 A read-write flat-keyed file which exists on non-root cgroups.
1912 A read-write nested-keyed file which exists on non-root
1926 When writing, any number of nested key-value pairs can be
1951 A read-only nested-keyed file.
1962 mechanism. Writeback sits between the memory and IO domains and
1963 regulates the proportion of dirty memory by balancing dirtying and
1966 The io controller, in conjunction with the memory controller,
1967 implements control of page cache writeback IOs. The memory controller
1968 defines the memory domain that dirty memory ratio is calculated and
1969 maintained for and the io controller defines the io domain which
1970 writes out dirty pages for the memory domain. Both system-wide and
1971 per-cgroup dirty memory states are examined and the more restrictive
1979 There are inherent differences in memory and writeback management
1980 which affects how cgroup ownership is tracked. Memory is tracked per
1985 As cgroup ownership for memory is tracked per page, there can be pages
1997 As memory controller assigns page ownership on the first use and
2008 amount of available memory capped by limits imposed by the
2009 memory controller and system-wide clean memory.
2013 total available memory and applied the same way as
2020 This is a cgroup v2 controller for IO workload protection. You provide a group
2022 controller will throttle any peers that have a lower latency target than the
2042 your real setting, setting at 10-15% higher than the value in io.stat.
2048 target the controller doesn't do anything. Once a group starts missing its
2052 - Queue depth throttling. This is the number of outstanding IO's a group is
2056 - Artificial delay induction. There are certain types of IO that cannot be
2079 If the controller is enabled you will see extra stats in io.stat in
2103 no-change
2106 promote-to-rt
2107 For requests that have a non-RT I/O priority class, change it into RT.
2111 restrict-to-be
2121 none-to-rt
2122 Deprecated. Just an alias for promote-to-rt.
2126 +----------------+---+
2127 | no-change | 0 |
2128 +----------------+---+
2129 | promote-to-rt | 1 |
2130 +----------------+---+
2131 | restrict-to-be | 2 |
2132 +----------------+---+
2134 +----------------+---+
2138 +-------------------------------+---+
2140 +-------------------------------+---+
2141 | IOPRIO_CLASS_RT (real-time) | 1 |
2142 +-------------------------------+---+
2144 +-------------------------------+---+
2146 +-------------------------------+---+
2150 - If I/O priority class policy is promote-to-rt, change the request I/O
2153 - If I/O priority class policy is not promote-to-rt, translate the I/O priority
2159 ---
2161 The process number controller is used to allow a cgroup to stop any
2166 controllers cannot prevent, thus warranting its own controller. For
2168 hitting memory restrictions.
2170 Note that PIDs used in this controller refer to TIDs, process IDs as
2178 A read-write single value file which exists on non-root
2184 A read-only single value file which exists on all cgroups.
2194 through fork() or clone(). These will return -EAGAIN if the creation
2199 ------
2201 The "cpuset" controller provides a mechanism for constraining
2202 the CPU and memory node placement of tasks to only the resources
2206 memory placement to reduce cross-node memory access and contention
2209 The "cpuset" controller is hierarchical. That means the controller
2210 cannot use CPUs or memory nodes not allowed in its parent.
2217 A read-write multiple values file which exists on non-root
2218 cpuset-enabled cgroups.
2225 The CPU numbers are comma-separated numbers or ranges.
2229 0-4,6,8-10
2232 setting as the nearest cgroup ancestor with a non-empty
2239 A read-only multiple values file which exists on all
2240 cpuset-enabled cgroups.
2256 A read-write multiple values file which exists on non-root
2257 cpuset-enabled cgroups.
2259 It lists the requested memory nodes to be used by tasks within
2260 this cgroup. The actual list of memory nodes granted, however,
2262 from the requested memory nodes.
2264 The memory node numbers are comma-separated numbers or ranges.
2268 0-1,3
2271 setting as the nearest cgroup ancestor with a non-empty
2272 "cpuset.mems" or all the available memory nodes if none
2276 and won't be affected by any memory nodes hotplug events.
2278 Setting a non-empty value to "cpuset.mems" causes memory of
2280 they are currently using memory outside of the designated nodes.
2282 There is a cost for this memory migration. The migration
2283 may not be complete and some memory pages may be left behind.
2290 A read-only multiple values file which exists on all
2291 cpuset-enabled cgroups.
2293 It lists the onlined memory nodes that are actually granted to
2294 this cgroup by its parent. These memory nodes are allowed to
2297 If "cpuset.mems" is empty, it shows all the memory nodes from the
2300 the memory nodes listed in "cpuset.mems" can be granted. In this
2303 Its value will be affected by memory nodes hotplug events.
2306 A read-write multiple values file which exists on non-root
2307 cpuset-enabled cgroups.
2336 A read-only multiple values file which exists on all non-root
2337 cpuset-enabled cgroups.
2349 A read-only and root cgroup only multiple values file.
2356 A read-write single value file which exists on non-root
2357 cpuset-enabled cgroups. This flag is owned by the parent cgroup
2363 "member" Non-root member of a partition
2368 A cpuset partition is a collection of cpuset-enabled cgroups with
2375 There are two types of partitions - local and remote. A local
2391 be changed. All other non-root cgroups start out as "member".
2404 two possible states - valid or invalid. An invalid partition
2415 "member" Non-root member of a partition
2442 A valid non-root parent partition may distribute out all its CPUs
2461 A user can pre-configure certain CPUs to an isolated state
2467 Device controller
2468 -----------------
2470 Device controller manages access to device files. It includes both
2474 Cgroup v2 device controller has no interface files and is implemented
2479 on the return value the attempt will succeed or fail with -EPERM.
2484 If the program returns 0, the attempt fails with -EPERM, otherwise it
2492 ----
2494 The "rdma" controller regulates the distribution and accounting of
2501 A readwrite nested-keyed file that exists for all the cgroups
2522 A read-only file that describes current resource usage.
2531 -------
2533 The HugeTLB controller allows to limit the HugeTLB usage per control group and
2534 enforces the controller limit during page fault.
2548 A read-only flat-keyed file which exists on non-root cgroups.
2559 Similar to memory.numa_stat, it shows the numa information of the
2561 use hugetlb pages are included. The per-node values are in bytes.
2564 ----
2568 cgroup resources. Controller is enabled by the CONFIG_CGROUP_MISC config
2571 A resource can be added to the controller via enum misc_res_type{} in the
2577 uncharge APIs. All of the APIs to interact with misc controller are in
2583 Miscellaneous controller provides 3 interface files. If two misc resources (res_a and res_b) are re…
2586 A read-only flat-keyed file shown only in the root cgroup. It shows
2595 A read-only flat-keyed file shown in the all cgroups. It shows
2603 A read-write flat-keyed file shown in the non root cgroups. Allowed
2622 A read-only flat-keyed file which exists on non-root cgroups. The
2640 ------
2645 perf_event controller, if not mounted on a legacy hierarchy, is
2647 always be filtered by cgroup v2 path. The controller can still be
2651 Non-normative information
2652 -------------------------
2658 CPU controller root cgroup process behaviour
2668 appropriately so the neutral - nice 0 - value is 100 instead of 1024).
2671 IO controller root cgroup process behaviour
2684 ------
2703 The path '/batchjobs/container_id1' can be considered as system-data
2708 # ls -l /proc/self/ns/cgroup
2709 lrwxrwxrwx 1 root root 0 2014-07-15 10:37 /proc/self/ns/cgroup -> cgroup:[4026531835]
2715 # ls -l /proc/self/ns/cgroup
2716 lrwxrwxrwx 1 root root 0 2014-07-15 10:35 /proc/self/ns/cgroup -> cgroup:[4026532183]
2720 When some thread from a multi-threaded process unshares its cgroup
2732 ------------------
2743 # ~/unshare -c # unshare cgroupns in some cgroup
2751 Each process gets its namespace-specific view of "/proc/$PID/cgroup"
2782 ----------------------
2811 ---------------------------------
2814 running inside a non-init cgroup namespace::
2816 # mount -t cgroup2 none $MOUNT_POINT
2823 the view of cgroup hierarchy by namespace-private cgroupfs mount
2836 --------------------------------
2839 address_space_operations->writepage[s]() to annotate bio's using the
2856 super_block by setting SB_I_CGROUPWB in ->s_iflags. This allows for
2873 - Multiple hierarchies including named ones are not supported.
2875 - All v1 mount options are not supported.
2877 - The "tasks" file is removed and "cgroup.procs" is not sorted.
2879 - "cgroup.clone_children" is removed.
2881 - /proc/cgroups is meaningless for v2. Use "cgroup.controllers" file
2889 --------------------
2895 For example, as there is only one instance of each controller, utility
2902 the specific controller.
2906 each controller on its own hierarchy. Only closely related ones, such
2925 Also, as a controller couldn't have any expectation regarding the
2927 controller had to assume that all other controllers were attached to
2934 depending on the specific controller. In other words, hierarchy may
2937 how memory is distributed beyond a certain level while still wanting
2942 ------------------
2950 Generally, in-process knowledge is available only to the process
2951 itself; thus, unlike service-level organization of processes,
2958 sub-hierarchies and control resource distributions along them. This
2959 effectively raised cgroup to the status of a syscall-like API exposed
2969 that the process would actually be operating on its own sub-hierarchy.
2973 system-management pseudo filesystem. cgroup ended up with interface
2976 individual applications through the ill-defined delegation mechanism
2986 -------------------------------------------
2994 The cpu controller considered threads and cgroups as equivalents and
2997 cycles and the number of internal threads fluctuated - the ratios
3003 The io controller implicitly created a hidden leaf node for each
3011 The memory controller didn't have a way to control what happened
3013 clearly defined. There were attempts to add ad-hoc behaviors and
3027 ----------------------
3031 was how an empty cgroup was notified - a userland helper binary was
3034 to in-kernel event delivery filtering mechanism further complicating
3037 Controller interfaces were problematic too. An extreme example is
3049 formats and units even in the same controller.
3055 Controller Issues and Remedies
3056 ------------------------------
3058 Memory subsection
3063 global reclaim prefers is opt-in, rather than opt-out. The costs for
3073 becomes self-defeating.
3075 The memory.low boundary on the other hand is a top-down allocated
3084 available memory. The memory consumption of workloads varies during
3092 The memory.high boundary on the other hand can be set much more
3098 and make corrections until the minimal memory footprint that still
3105 system than killing the group. Otherwise, memory.max is there to
3109 Setting the original memory.limit_in_bytes below the current usage was
3111 limit setting to fail. memory.max on the other hand will first set the
3113 new limit is met - or the task writing to memory.max is killed.
3115 The combined memory+swap accounting and limiting is replaced by real
3118 The main argument for a combined memory+swap facility in the original
3120 able to swap all anonymous memory of a child group, regardless of the
3122 groups can sabotage swapping by other means - such as referencing its
3123 anonymous memory in a tight loop - and an admin can not assume full