Lines Matching +full:non +full:- +full:descriptive
1 .. _cgroup-v2:
11 conventions of cgroup v2. It describes all userland-visible aspects
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.
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
156 is no longer referenced in its current hierarchy. Because per-cgroup
163 to inter-controller dependencies, other controllers may need to be
184 ignored on non-init namespace mounts. Please refer to the
201 option is ignored on non-init namespace mounts.
209 behavior but is a mount-option to avoid regressing setups
223 controller. The pre-allocated pool does not belong to anyone.
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
393 between threads in a non-leaf cgroup and its child cgroups. Each
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 -----------------------
442 # echo "+cpu +memory -io" > cgroup.subtree_control
451 Consider the following sub-hierarchy. The enabled controllers are
454 A(cpu,memory) - B(memory) - C()
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
487 Non-root cgroups can distribute domain resources to their children
502 refer to the Non-normative information section in the Controllers
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 ----------
598 inherent trade-offs between migration and various hot paths in terms
604 resource structure once on start-up. Dynamic adjustments to resource
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
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 '-'
928 name prefixed with '+' enables the controller and '-'
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 ---
1075 A read-only flat-keyed file.
1080 - usage_usec
1081 - user_usec
1082 - system_usec
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
1096 For non idle groups (cpu.idle = 0), the weight is in the
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.
1177 ------
1185 While not completely water-tight, all major memory usages by a given
1190 - Userland memory - page cache and anonymous memory.
1192 - Kernel data structures such as dentries and inodes.
1194 - TCP socket buffers.
1207 A read-only single value file which exists on non-root
1214 A read-write single value file which exists on non-root
1240 A read-write single value file which exists on non-root
1243 Best-effort memory protection. If the memory usage of a
1263 A read-write single value file which exists on non-root
1277 A read-write single value file which exists on non-root
1286 In default configuration regular 0-order allocations always
1291 as -ENOMEM or silently ignore in cases like disk readahead.
1294 A write-only nested-keyed file which exists for all cgroups.
1312 specified amount, -EAGAIN is returned.
1322 A read-only single value file which exists on non-root
1329 A read-write single value file which exists on non-root
1339 Tasks with the OOM protection (oom_score_adj set to -1000)
1347 A read-only flat-keyed file which exists on non-root cgroups.
1361 boundary is over-committed.
1381 considered as an option, e.g. for failed high-order
1397 A read-only flat-keyed file which exists on non-root cgroups.
1400 types of memory, type-specific details, and other information
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
1438 Amount of memory used for storing per-cpu kernel
1448 Amount of cached filesystem data that is swap-backed,
1485 Amount of memory, swap-backed and filesystem-backed,
1491 the value for the foo counter, since the foo counter is type-based, not
1492 list-based.
1503 Amount of memory used for storing in-kernel data
1595 A read-only nested-keyed file which exists on non-root cgroups.
1598 types of memory, type-specific details, and other information
1620 A read-only single value file which exists on non-root
1627 A read-write single value file which exists on non-root
1632 allow userspace to implement custom out-of-memory procedures.
1643 A read-only single value file which exists on non-root
1650 A read-write single value file which exists on non-root
1657 A read-only flat-keyed file which exists on non-root cgroups.
1673 because of running out of swap system-wide or max
1682 A read-only single value file which exists on non-root
1689 A read-write single value file which exists on non-root
1697 A read-write single value file. The default value is "1". The
1712 A read-only nested-keyed file.
1722 Over-committing on high limit (sum of high limits > available 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
1751 To which cgroup the area will be charged is in-deterministic; however,
1762 --
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
1807 enable Weight-based control enable
1839 devices which show wide temporary behavior changes - e.g. a
1850 A read-write nested-keyed file which exists only on the root
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.
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
2009 memory controller and system-wide clean memory.
2042 your real setting, setting at 10-15% higher than the value in io.stat.
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
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 ---
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 ------
2206 memory placement to reduce cross-node memory access and contention
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.
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
2278 Setting a non-empty value to "cpuset.mems" causes memory of
2290 A read-only multiple values file which exists on all
2291 cpuset-enabled cgroups.
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
2422 In the case of an invalid partition root, a descriptive string on
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
2468 -----------------
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 ----
2501 A readwrite nested-keyed file that exists for all the cgroups
2522 A read-only file that describes current resource usage.
2531 -------
2548 A read-only flat-keyed file which exists on non-root cgroups.
2561 use hugetlb pages are included. The per-node values are in bytes.
2564 ----
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 ------
2651 Non-normative information
2652 -------------------------
2668 appropriately so the neutral - nice 0 - value is 100 instead of 1024).
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 --------------------
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 -------------------------------------------
2997 cycles and the number of internal threads fluctuated - the ratios
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
3056 ------------------------------
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
3113 new limit is met - or the task writing to memory.max is killed.
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