Lines Matching +full:cpu +full:- +full:viewed
9 conventions of cgroup v2. It describes all userland-visible aspects
12 v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgroup-v1>`.
17 1-1. Terminology
18 1-2. What is cgroup?
20 2-1. Mounting
21 2-2. Organizing Processes and Threads
22 2-2-1. Processes
23 2-2-2. Threads
24 2-3. [Un]populated Notification
25 2-4. Controlling Controllers
26 2-4-1. Enabling and Disabling
27 2-4-2. Top-down Constraint
28 2-4-3. No Internal Process Constraint
29 2-5. Delegation
30 2-5-1. Model of Delegation
31 2-5-2. Delegation Containment
32 2-6. Guidelines
33 2-6-1. Organize Once and Control
34 2-6-2. Avoid Name Collisions
36 3-1. Weights
37 3-2. Limits
38 3-3. Protections
39 3-4. Allocations
41 4-1. Format
42 4-2. Conventions
43 4-3. Core Interface Files
45 5-1. CPU
46 5-1-1. CPU Interface Files
47 5-2. Memory
48 5-2-1. Memory Interface Files
49 5-2-2. Usage Guidelines
50 5-2-3. Memory Ownership
51 5-3. IO
52 5-3-1. IO Interface Files
53 5-3-2. Writeback
54 5-3-3. IO Latency
55 5-3-3-1. How IO Latency Throttling Works
56 5-3-3-2. IO Latency Interface Files
57 5-4. PID
58 5-4-1. PID Interface Files
59 5-5. Cpuset
60 5.5-1. Cpuset Interface Files
61 5-6. Device
62 5-7. RDMA
63 5-7-1. RDMA Interface Files
64 5-8. HugeTLB
65 5.8-1. HugeTLB Interface Files
66 5-8. Misc
67 5-8-1. perf_event
68 5-N. Non-normative information
69 5-N-1. CPU controller root cgroup process behaviour
70 5-N-2. IO controller root cgroup process behaviour
72 6-1. Basics
73 6-2. The Root and Views
74 6-3. Migration and setns(2)
75 6-4. Interaction with Other Namespaces
77 P-1. Filesystem Support for Writeback
80 R-1. Multiple Hierarchies
81 R-2. Thread Granularity
82 R-3. Competition Between Inner Nodes and Threads
83 R-4. Other Interface Issues
84 R-5. Controller Issues and Remedies
85 R-5-1. Memory
92 -----------
101 ---------------
107 cgroup is largely composed of two parts - the core and controllers.
123 hierarchical - if a controller is enabled on a cgroup, it affects all
125 sub-hierarchy of the cgroup. When a controller is enabled on a nested
135 --------
140 # mount -t cgroup2 none $MOUNT_POINT
150 is no longer referenced in its current hierarchy. Because per-cgroup
157 to inter-controller dependencies, other controllers may need to be
179 ignored on non-init namespace mounts. Please refer to the
189 option is ignored on non-init namespace mounts.
198 behavior but is a mount-option to avoid regressing setups
204 --------------------------------
210 A child cgroup can be created by creating a sub-directory::
215 structure. Each cgroup has a read-writable interface file
217 belong to the cgroup one-per-line. The PIDs are not ordered and the
248 0::/test-cgroup/test-cgroup-nested
255 0::/test-cgroup/test-cgroup-nested (deleted)
281 constraint - threaded controllers can be enabled on non-leaf cgroups
305 - As the cgroup will join the parent's resource domain. The parent
308 - When the parent is an unthreaded domain, it must not have any domain
312 Topology-wise, a cgroup can be in an invalid state. Please consider
315 A (threaded domain) - B (threaded) - C (domain, just created)
330 threads in the cgroup. Except that the operations are per-thread
331 instead of per-process, "cgroup.threads" has the same format and
353 between threads in a non-leaf cgroup and its child cgroups. Each
358 --------------------------
360 Each non-root cgroup has a "cgroup.events" file which contains
361 "populated" field indicating whether the cgroup's sub-hierarchy has
365 example, to start a clean-up operation after all processes of a given
366 sub-hierarchy have exited. The populated state updates and
367 notifications are recursive. Consider the following sub-hierarchy
371 A(4) - B(0) - C(1)
381 -----------------------
390 cpu io memory
395 # echo "+cpu +memory -io" > cgroup.subtree_control
404 Consider the following sub-hierarchy. The enabled controllers are
407 A(cpu,memory) - B(memory) - C()
410 As A has "cpu" and "memory" enabled, A will control the distribution
411 of CPU cycles and memory to its children, in this case, B. As B has
412 "memory" enabled but not "CPU", C and D will compete freely on CPU
417 files in the child cgroups. In the above example, enabling "cpu" on B
418 would create the "cpu." prefixed controller interface files in C and
421 controller interface files - anything which doesn't start with
425 Top-down Constraint
428 Resources are distributed top-down and a cgroup can further distribute
430 parent. This means that all non-root "cgroup.subtree_control" files
440 Non-root cgroups can distribute domain resources to their children
455 refer to the Non-normative information section in the Controllers
468 ----------
488 delegated, the user can build sub-hierarchy under the directory,
492 happens in the delegated sub-hierarchy, nothing can escape the
496 cgroups in or nesting depth of a delegated sub-hierarchy; however,
503 A delegated sub-hierarchy is contained in the sense that processes
504 can't be moved into or out of the sub-hierarchy by the delegatee.
507 requiring the following conditions for a process with a non-root euid
511 - The writer must have write access to the "cgroup.procs" file.
513 - The writer must have write access to the "cgroup.procs" file of the
517 processes around freely in the delegated sub-hierarchy it can't pull
518 in from or push out to outside the sub-hierarchy.
524 ~~~~~~~~~~~~~ - C0 - C00
527 ~~~~~~~~~~~~~ - C1 - C10
534 will be denied with -EACCES.
539 is not reachable, the migration is rejected with -ENOENT.
543 ----------
551 inherent trade-offs between migration and various hot paths in terms
557 resource structure once on start-up. Dynamic adjustments to resource
590 -------
596 work-conserving. Due to the dynamic nature, this model is usually
607 "cpu.weight" proportionally distributes CPU cycles to active children
612 ------
615 Limits can be over-committed - the sum of the limits of children can
620 As limits can be over-committed, all configuration combinations are
629 -----------
634 soft boundaries. Protections can also be over-committed in which case
641 As protections can be over-committed, all configuration combinations
645 "memory.low" implements best-effort memory protection and is an
650 -----------
653 resource. Allocations can't be over-committed - the sum of the
660 As allocations can't be over-committed, some configuration
665 "cpu.rt.max" hard-allocates realtime slices and is an example of this
673 ------
678 New-line separated values
686 (when read-only or multiple values can be written at once)
712 -----------
714 - Settings for a single feature should be contained in a single file.
716 - The root cgroup should be exempt from resource control and thus
719 - The default time unit is microseconds. If a different unit is ever
722 - A parts-per quantity should use a percentage decimal with at least
723 two digit fractional part - e.g. 13.40.
725 - If a controller implements weight based resource distribution, its
731 - If a controller implements an absolute resource guarantee and/or
740 - If a setting has a configurable default value and keyed specific
754 # cat cgroup-example-interface-file
760 # echo 125 > cgroup-example-interface-file
764 # echo "default 125" > cgroup-example-interface-file
768 # echo "8:16 170" > cgroup-example-interface-file
772 # echo "8:0 default" > cgroup-example-interface-file
773 # cat cgroup-example-interface-file
777 - For events which are not very high frequency, an interface file
784 --------------------
790 A read-write single value file which exists on non-root
796 - "domain" : A normal valid domain cgroup.
798 - "domain threaded" : A threaded domain cgroup which is
801 - "domain invalid" : A cgroup which is in an invalid state.
805 - "threaded" : A threaded cgroup which is a member of a
812 A read-write new-line separated values file which exists on
816 the cgroup one-per-line. The PIDs are not ordered and the
825 - It must have write access to the "cgroup.procs" file.
827 - It must have write access to the "cgroup.procs" file of the
830 When delegating a sub-hierarchy, write access to this file
838 A read-write new-line separated values file which exists on
842 the cgroup one-per-line. The TIDs are not ordered and the
851 - It must have write access to the "cgroup.threads" file.
853 - The cgroup that the thread is currently in must be in the
856 - It must have write access to the "cgroup.procs" file of the
859 When delegating a sub-hierarchy, write access to this file
863 A read-only space separated values file which exists on all
870 A read-write space separated values file which exists on all
877 Space separated list of controllers prefixed with '+' or '-'
879 name prefixed with '+' enables the controller and '-'
885 A read-only flat-keyed file which exists on non-root cgroups.
897 A read-write single value files. The default is "max".
904 A read-write single value files. The default is "max".
911 A read-only flat-keyed file with the following entries:
929 A read-write single value file which exists on non-root cgroups.
952 create new sub-cgroups.
957 CPU section in Controllers
958 ---
960 The "cpu" controllers regulates distribution of CPU cycles. This
969 provided by a CPU, as well as the maximum desired frequency, which should not
970 be exceeded by a CPU.
973 the cpu controller can only be enabled when all RT processes are in
977 before the cpu controller can be enabled.
980 CPU Interface Files argument
985 cpu.stat
986 A read-only flat-keyed file.
991 - usage_usec
992 - user_usec
993 - system_usec
997 - nr_periods
998 - nr_throttled
999 - throttled_usec
1001 cpu.weight
1002 A read-write single value file which exists on non-root
1007 cpu.weight.nice
1008 A read-write single value file which exists on non-root
1011 The nice value is in the range [-20, 19].
1014 "cpu.weight" and allows reading and setting weight using the
1019 cpu.max
1020 A read-write two value file which exists on non-root cgroups.
1031 cpu.pressure
1032 A read-only nested-key file which exists on non-root cgroups.
1034 Shows pressure stall information for CPU. See
1037 cpu.uclamp.min
1038 A read-write single value file which exists on non-root cgroups.
1050 `cpu.uclamp.max`.
1052 cpu.uclamp.max
1053 A read-write single value file which exists on non-root cgroups.
1066 ------
1074 While not completely water-tight, all major memory usages by a given
1079 - Userland memory - page cache and anonymous memory.
1081 - Kernel data structures such as dentries and inodes.
1083 - TCP socket buffers.
1096 A read-only single value file which exists on non-root
1103 A read-write single value file which exists on non-root
1129 A read-write single value file which exists on non-root
1132 Best-effort memory protection. If the memory usage of a
1152 A read-write single value file which exists on non-root
1164 A read-write single value file which exists on non-root
1173 In default configuration regular 0-order allocations always
1178 as -ENOMEM or silently ignore in cases like disk readahead.
1185 A read-write single value file which exists on non-root
1195 Tasks with the OOM protection (oom_score_adj set to -1000)
1203 A read-only flat-keyed file which exists on non-root cgroups.
1217 boundary is over-committed.
1237 considered as an option, e.g. for failed high-order
1250 A read-only flat-keyed file which exists on non-root cgroups.
1253 types of memory, type-specific details, and other information
1262 If the entry has no per-node counter(or not show in the
1263 mempry.numa_stat). We use 'npn'(non-per-node) as the tag
1278 Amount of memory used for storing per-cpu kernel
1285 Amount of cached filesystem data that is swap-backed,
1304 Amount of memory, swap-backed and filesystem-backed,
1310 the value for the foo counter, since the foo counter is type-based, not
1311 list-based.
1322 Amount of memory used for storing in-kernel data
1387 A read-only nested-keyed file which exists on non-root cgroups.
1390 types of memory, type-specific details, and other information
1397 application's CPU allocation.
1412 A read-only single value file which exists on non-root
1419 A read-write single value file which exists on non-root
1424 allow userspace to implement custom out-of-memory procedures.
1435 A read-write single value file which exists on non-root
1442 A read-only flat-keyed file which exists on non-root cgroups.
1458 because of running out of swap system-wide or max
1467 A read-only nested-key file which exists on non-root cgroups.
1477 Over-committing on high limit (sum of high limits > available memory)
1491 pressure - how much the workload is being impacted due to lack of
1492 memory - is necessary to determine whether a workload needs more
1506 To which cgroup the area will be charged is in-deterministic; however,
1517 --
1522 only if cfq-iosched is in use and neither scheme is available for
1523 blk-mq devices.
1530 A read-only nested-keyed file.
1550 A read-write nested-keyed file with exists only on the root
1562 enable Weight-based control enable
1594 devices which show wide temporary behavior changes - e.g. a
1605 A read-write nested-keyed file with exists only on the root
1618 model The cost model in use - "linear"
1644 generate device-specific coefficients.
1647 A read-write flat-keyed file which exists on non-root cgroups.
1667 A read-write nested-keyed file which exists on non-root
1681 When writing, any number of nested key-value pairs can be
1706 A read-only nested-key file which exists on non-root cgroups.
1725 writes out dirty pages for the memory domain. Both system-wide and
1726 per-cgroup dirty memory states are examined and the more restrictive
1764 memory controller and system-wide clean memory.
1797 your real setting, setting at 10-15% higher than the value in io.stat.
1807 - Queue depth throttling. This is the number of outstanding IO's a group is
1811 - Artificial delay induction. There are certain types of IO that cannot be
1852 ---
1871 A read-write single value file which exists on non-root
1877 A read-only single value file which exists on all cgroups.
1887 through fork() or clone(). These will return -EAGAIN if the creation
1892 ------
1895 the CPU and memory node placement of tasks to only the resources
1899 memory placement to reduce cross-node memory access and contention
1910 A read-write multiple values file which exists on non-root
1911 cpuset-enabled cgroups.
1918 The CPU numbers are comma-separated numbers or ranges.
1922 0-4,6,8-10
1925 setting as the nearest cgroup ancestor with a non-empty
1929 and won't be affected by any CPU hotplug events.
1932 A read-only multiple values file which exists on all
1933 cpuset-enabled cgroups.
1946 Its value will be affected by CPU hotplug events.
1949 A read-write multiple values file which exists on non-root
1950 cpuset-enabled cgroups.
1957 The memory node numbers are comma-separated numbers or ranges.
1961 0-1,3
1964 setting as the nearest cgroup ancestor with a non-empty
1972 A read-only multiple values file which exists on all
1973 cpuset-enabled cgroups.
1988 A read-write single value file which exists on non-root
1989 cpuset-enabled cgroups. This flag is owned by the parent cgroup
1994 "root" - a partition root
1995 "member" - a non-root member of a partition
2022 child partitions. There must be at least one cpu left in the
2032 "cpuset.cpus" or cpu hotplug can cause the state of the partition
2036 "member" Non-root member of a partition
2041 above are true and at least one CPU from "cpuset.cpus" is
2049 The cpu affinity of all the tasks in the cgroup will then be
2054 can now be granted by its parent. In this case, the cpu
2062 -----------------
2073 the attempt will succeed or fail with -EPERM.
2078 If the program returns 0, the attempt fails with -EPERM, otherwise
2086 ----
2095 A readwrite nested-keyed file that exists for all the cgroups
2116 A read-only file that describes current resource usage.
2125 -------
2142 A read-only flat-keyed file which exists on non-root cgroups.
2153 ----
2164 Non-normative information
2165 -------------------------
2171 CPU controller root cgroup process behaviour
2174 When distributing CPU cycles in the root cgroup each thread in this
2181 appropriately so the neutral - nice 0 - value is 100 instead of 1024).
2197 ------
2216 The path '/batchjobs/container_id1' can be considered as system-data
2221 # ls -l /proc/self/ns/cgroup
2222 lrwxrwxrwx 1 root root 0 2014-07-15 10:37 /proc/self/ns/cgroup -> cgroup:[4026531835]
2228 # ls -l /proc/self/ns/cgroup
2229 lrwxrwxrwx 1 root root 0 2014-07-15 10:35 /proc/self/ns/cgroup -> cgroup:[4026532183]
2233 When some thread from a multi-threaded process unshares its cgroup
2245 ------------------
2256 # ~/unshare -c # unshare cgroupns in some cgroup
2264 Each process gets its namespace-specific view of "/proc/$PID/cgroup"
2295 ----------------------
2324 ---------------------------------
2327 running inside a non-init cgroup namespace::
2329 # mount -t cgroup2 none $MOUNT_POINT
2336 the view of cgroup hierarchy by namespace-private cgroupfs mount
2349 --------------------------------
2352 address_space_operations->writepage[s]() to annotate bio's using the
2369 super_block by setting SB_I_CGROUPWB in ->s_iflags. This allows for
2386 - Multiple hierarchies including named ones are not supported.
2388 - All v1 mount options are not supported.
2390 - The "tasks" file is removed and "cgroup.procs" is not sorted.
2392 - "cgroup.clone_children" is removed.
2394 - /proc/cgroups is meaningless for v2. Use "cgroup.controllers" file
2402 --------------------
2420 as the cpu and cpuacct controllers, made sense to be put on the same
2448 be collapsed from leaf towards root when viewed from specific
2451 to control how CPU cycles are distributed.
2455 ------------------
2463 Generally, in-process knowledge is available only to the process
2464 itself; thus, unlike service-level organization of processes,
2471 sub-hierarchies and control resource distributions along them. This
2472 effectively raised cgroup to the status of a syscall-like API exposed
2482 that the process would actually be operating on its own sub-hierarchy.
2486 system-management pseudo filesystem. cgroup ended up with interface
2489 individual applications through the ill-defined delegation mechanism
2499 -------------------------------------------
2507 The cpu controller considered threads and cgroups as equivalents and
2509 fell flat when children wanted to be allocated specific ratios of CPU
2510 cycles and the number of internal threads fluctuated - the ratios
2526 clearly defined. There were attempts to add ad-hoc behaviors and
2540 ----------------------
2544 was how an empty cgroup was notified - a userland helper binary was
2547 to in-kernel event delivery filtering mechanism further complicating
2569 ------------------------------
2576 global reclaim prefers is opt-in, rather than opt-out. The costs for
2586 becomes self-defeating.
2588 The memory.low boundary on the other hand is a top-down allocated
2626 new limit is met - or the task writing to memory.max is killed.
2635 groups can sabotage swapping by other means - such as referencing its
2636 anonymous memory in a tight loop - and an admin can not assume full