Lines Matching +full:psi +full:- +full:l
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
215 --------------------------------
221 A child cgroup can be created by creating a sub-directory::
226 structure. Each cgroup has a read-writable interface file
228 belong to the cgroup one-per-line. The PIDs are not ordered and the
259 0::/test-cgroup/test-cgroup-nested
266 0::/test-cgroup/test-cgroup-nested (deleted)
292 constraint - threaded controllers can be enabled on non-leaf cgroups
316 - As the cgroup will join the parent's resource domain. The parent
319 - When the parent is an unthreaded domain, it must not have any domain
323 Topology-wise, a cgroup can be in an invalid state. Please consider
326 A (threaded domain) - B (threaded) - C (domain, just created)
341 threads in the cgroup. Except that the operations are per-thread
342 instead of per-process, "cgroup.threads" has the same format and
364 between threads in a non-leaf cgroup and its child cgroups. Each
369 --------------------------
371 Each non-root cgroup has a "cgroup.events" file which contains
372 "populated" field indicating whether the cgroup's sub-hierarchy has
376 example, to start a clean-up operation after all processes of a given
377 sub-hierarchy have exited. The populated state updates and
378 notifications are recursive. Consider the following sub-hierarchy
382 A(4) - B(0) - C(1)
392 -----------------------
406 # echo "+cpu +memory -io" > cgroup.subtree_control
415 Consider the following sub-hierarchy. The enabled controllers are
418 A(cpu,memory) - B(memory) - C()
432 controller interface files - anything which doesn't start with
436 Top-down Constraint
439 Resources are distributed top-down and a cgroup can further distribute
441 parent. This means that all non-root "cgroup.subtree_control" files
451 Non-root cgroups can distribute domain resources to their children
466 refer to the Non-normative information section in the Controllers
479 ----------
499 delegated, the user can build sub-hierarchy under the directory,
503 happens in the delegated sub-hierarchy, nothing can escape the
507 cgroups in or nesting depth of a delegated sub-hierarchy; however,
514 A delegated sub-hierarchy is contained in the sense that processes
515 can't be moved into or out of the sub-hierarchy by the delegatee.
518 requiring the following conditions for a process with a non-root euid
522 - The writer must have write access to the "cgroup.procs" file.
524 - The writer must have write access to the "cgroup.procs" file of the
528 processes around freely in the delegated sub-hierarchy it can't pull
529 in from or push out to outside the sub-hierarchy.
535 ~~~~~~~~~~~~~ - C0 - C00
538 ~~~~~~~~~~~~~ - C1 - C10
545 will be denied with -EACCES.
550 is not reachable, the migration is rejected with -ENOENT.
554 ----------
562 inherent trade-offs between migration and various hot paths in terms
568 resource structure once on start-up. Dynamic adjustments to resource
601 -------
607 work-conserving. Due to the dynamic nature, this model is usually
623 ------
626 Limits can be over-committed - the sum of the limits of children can
631 As limits can be over-committed, all configuration combinations are
640 -----------
645 soft boundaries. Protections can also be over-committed in which case
652 As protections can be over-committed, all configuration combinations
656 "memory.low" implements best-effort memory protection and is an
661 -----------
664 resource. Allocations can't be over-committed - the sum of the
671 As allocations can't be over-committed, some configuration
676 "cpu.rt.max" hard-allocates realtime slices and is an example of this
684 ------
689 New-line separated values
697 (when read-only or multiple values can be written at once)
723 -----------
725 - Settings for a single feature should be contained in a single file.
727 - The root cgroup should be exempt from resource control and thus
730 - The default time unit is microseconds. If a different unit is ever
733 - A parts-per quantity should use a percentage decimal with at least
734 two digit fractional part - e.g. 13.40.
736 - If a controller implements weight based resource distribution, its
742 - If a controller implements an absolute resource guarantee and/or
751 - If a setting has a configurable default value and keyed specific
765 # cat cgroup-example-interface-file
771 # echo 125 > cgroup-example-interface-file
775 # echo "default 125" > cgroup-example-interface-file
779 # echo "8:16 170" > cgroup-example-interface-file
783 # echo "8:0 default" > cgroup-example-interface-file
784 # cat cgroup-example-interface-file
788 - For events which are not very high frequency, an interface file
795 --------------------
800 A read-write single value file which exists on non-root
806 - "domain" : A normal valid domain cgroup.
808 - "domain threaded" : A threaded domain cgroup which is
811 - "domain invalid" : A cgroup which is in an invalid state.
815 - "threaded" : A threaded cgroup which is a member of a
822 A read-write new-line separated values file which exists on
826 the cgroup one-per-line. The PIDs are not ordered and the
835 - It must have write access to the "cgroup.procs" file.
837 - It must have write access to the "cgroup.procs" file of the
840 When delegating a sub-hierarchy, write access to this file
848 A read-write new-line separated values file which exists on
852 the cgroup one-per-line. The TIDs are not ordered and the
861 - It must have write access to the "cgroup.threads" file.
863 - The cgroup that the thread is currently in must be in the
866 - It must have write access to the "cgroup.procs" file of the
869 When delegating a sub-hierarchy, write access to this file
873 A read-only space separated values file which exists on all
880 A read-write space separated values file which exists on all
887 Space separated list of controllers prefixed with '+' or '-'
889 name prefixed with '+' enables the controller and '-'
895 A read-only flat-keyed file which exists on non-root cgroups.
907 A read-write single value files. The default is "max".
914 A read-write single value files. The default is "max".
921 A read-only flat-keyed file with the following entries:
939 A read-write single value file which exists on non-root cgroups.
962 create new sub-cgroups.
965 A write-only single value file which exists in non-root cgroups.
977 the whole thread-group.
980 A read-write single value file that allowed values are "0" and "1".
983 Writing "0" to the file will disable the cgroup PSI accounting.
984 Writing "1" to the file will re-enable the cgroup PSI accounting.
986 This control attribute is not hierarchical, so disable or enable PSI
987 accounting in a cgroup does not affect PSI accounting in descendants
990 The reason this control attribute exists is that PSI accounts stalls for
992 This may cause non-negligible overhead for some workloads when under
994 be used to disable PSI accounting in the non-leaf cgroups.
997 A read-write nested-keyed file.
1000 :ref:`Documentation/accounting/psi.rst <psi>` for details.
1005 .. _cgroup-v2-cpu:
1008 ---
1036 A read-only flat-keyed file.
1041 - usage_usec
1042 - user_usec
1043 - system_usec
1047 - nr_periods
1048 - nr_throttled
1049 - throttled_usec
1050 - nr_bursts
1051 - burst_usec
1054 A read-write single value file which exists on non-root
1060 A read-write single value file which exists on non-root
1063 The nice value is in the range [-20, 19].
1072 A read-write two value file which exists on non-root cgroups.
1084 A read-write single value file which exists on non-root
1090 A read-write nested-keyed file.
1093 :ref:`Documentation/accounting/psi.rst <psi>` for details.
1096 A read-write single value file which exists on non-root cgroups.
1111 A read-write single value file which exists on non-root cgroups.
1124 ------
1132 While not completely water-tight, all major memory usages by a given
1137 - Userland memory - page cache and anonymous memory.
1139 - Kernel data structures such as dentries and inodes.
1141 - TCP socket buffers.
1154 A read-only single value file which exists on non-root
1161 A read-write single value file which exists on non-root
1187 A read-write single value file which exists on non-root
1190 Best-effort memory protection. If the memory usage of a
1210 A read-write single value file which exists on non-root
1222 A read-write single value file which exists on non-root
1231 In default configuration regular 0-order allocations always
1236 as -ENOMEM or silently ignore in cases like disk readahead.
1243 A write-only nested-keyed file which exists for all cgroups.
1261 specified amount, -EAGAIN is returned.
1271 A read-only single value file which exists on non-root
1278 A read-write single value file which exists on non-root
1288 Tasks with the OOM protection (oom_score_adj set to -1000)
1296 A read-only flat-keyed file which exists on non-root cgroups.
1310 boundary is over-committed.
1330 considered as an option, e.g. for failed high-order
1346 A read-only flat-keyed file which exists on non-root cgroups.
1349 types of memory, type-specific details, and other information
1358 If the entry has no per-node counter (or not show in the
1359 memory.numa_stat). We use 'npn' (non-per-node) as the tag
1387 Amount of memory used for storing per-cpu kernel
1397 Amount of cached filesystem data that is swap-backed,
1434 Amount of memory, swap-backed and filesystem-backed,
1440 the value for the foo counter, since the foo counter is type-based, not
1441 list-based.
1452 Amount of memory used for storing in-kernel data
1529 A read-only nested-keyed file which exists on non-root cgroups.
1532 types of memory, type-specific details, and other information
1554 A read-only single value file which exists on non-root
1561 A read-write single value file which exists on non-root
1566 allow userspace to implement custom out-of-memory procedures.
1577 A read-write single value file which exists on non-root
1584 A read-only flat-keyed file which exists on non-root cgroups.
1600 because of running out of swap system-wide or max
1609 A read-only single value file which exists on non-root
1616 A read-write single value file which exists on non-root
1624 A read-only nested-keyed file.
1627 :ref:`Documentation/accounting/psi.rst <psi>` for details.
1634 Over-committing on high limit (sum of high limits > available memory)
1648 pressure - how much the workload is being impacted due to lack of
1649 memory - is necessary to determine whether a workload needs more
1663 To which cgroup the area will be charged is in-deterministic; however,
1674 --
1679 only if cfq-iosched is in use and neither scheme is available for
1680 blk-mq devices.
1687 A read-only nested-keyed file.
1707 A read-write nested-keyed file which exists only on the root
1719 enable Weight-based control enable
1751 devices which show wide temporary behavior changes - e.g. a
1762 A read-write nested-keyed file which exists only on the root
1775 model The cost model in use - "linear"
1801 generate device-specific coefficients.
1804 A read-write flat-keyed file which exists on non-root cgroups.
1824 A read-write nested-keyed file which exists on non-root
1838 When writing, any number of nested key-value pairs can be
1863 A read-only nested-keyed file.
1866 :ref:`Documentation/accounting/psi.rst <psi>` for details.
1882 writes out dirty pages for the memory domain. Both system-wide and
1883 per-cgroup dirty memory states are examined and the more restrictive
1921 memory controller and system-wide clean memory.
1954 your real setting, setting at 10-15% higher than the value in io.stat.
1964 - Queue depth throttling. This is the number of outstanding IO's a group is
1968 - Artificial delay induction. There are certain types of IO that cannot be
2015 no-change
2018 none-to-rt
2023 restrict-to-be
2034 +-------------+---+
2035 | no-change | 0 |
2036 +-------------+---+
2037 | none-to-rt | 1 |
2038 +-------------+---+
2039 | rt-to-be | 2 |
2040 +-------------+---+
2041 | all-to-idle | 3 |
2042 +-------------+---+
2046 +-------------------------------+---+
2048 +-------------------------------+---+
2049 | IOPRIO_CLASS_RT (real-time) | 1 |
2050 +-------------------------------+---+
2052 +-------------------------------+---+
2054 +-------------------------------+---+
2058 - Translate the I/O priority class policy into a number.
2059 - Change the request I/O priority class into the maximum of the I/O priority
2063 ---
2082 A read-write single value file which exists on non-root
2088 A read-only single value file which exists on all cgroups.
2098 through fork() or clone(). These will return -EAGAIN if the creation
2103 ------
2110 memory placement to reduce cross-node memory access and contention
2121 A read-write multiple values file which exists on non-root
2122 cpuset-enabled cgroups.
2129 The CPU numbers are comma-separated numbers or ranges.
2133 0-4,6,8-10
2136 setting as the nearest cgroup ancestor with a non-empty
2143 A read-only multiple values file which exists on all
2144 cpuset-enabled cgroups.
2160 A read-write multiple values file which exists on non-root
2161 cpuset-enabled cgroups.
2168 The memory node numbers are comma-separated numbers or ranges.
2172 0-1,3
2175 setting as the nearest cgroup ancestor with a non-empty
2182 Setting a non-empty value to "cpuset.mems" causes memory of
2194 A read-only multiple values file which exists on all
2195 cpuset-enabled cgroups.
2210 A read-write single value file which exists on non-root
2211 cpuset-enabled cgroups. This flag is owned by the parent cgroup
2217 "member" Non-root member of a partition
2223 cannot be changed. All other non-root cgroups start out as
2243 two possible states - valid or invalid. An invalid partition
2254 "member" Non-root member of a partition
2286 A valid non-root parent partition may distribute out all its CPUs
2306 -----------------
2317 on the return value the attempt will succeed or fail with -EPERM.
2322 If the program returns 0, the attempt fails with -EPERM, otherwise it
2330 ----
2339 A readwrite nested-keyed file that exists for all the cgroups
2360 A read-only file that describes current resource usage.
2369 -------
2386 A read-only flat-keyed file which exists on non-root cgroups.
2399 use hugetlb pages are included. The per-node values are in bytes.
2402 ----
2424 A read-only flat-keyed file shown only in the root cgroup. It shows
2433 A read-only flat-keyed file shown in the non-root cgroups. It shows
2441 A read-write flat-keyed file shown in the non root cgroups. Allowed
2460 A read-only flat-keyed file which exists on non-root cgroups. The
2478 ------
2489 Non-normative information
2490 -------------------------
2506 appropriately so the neutral - nice 0 - value is 100 instead of 1024).
2522 ------
2541 The path '/batchjobs/container_id1' can be considered as system-data
2546 # ls -l /proc/self/ns/cgroup
2547 lrwxrwxrwx 1 root root 0 2014-07-15 10:37 /proc/self/ns/cgroup -> cgroup:[4026531835]
2553 # ls -l /proc/self/ns/cgroup
2554 lrwxrwxrwx 1 root root 0 2014-07-15 10:35 /proc/self/ns/cgroup -> cgroup:[4026532183]
2558 When some thread from a multi-threaded process unshares its cgroup
2570 ------------------
2581 # ~/unshare -c # unshare cgroupns in some cgroup
2589 Each process gets its namespace-specific view of "/proc/$PID/cgroup"
2620 ----------------------
2649 ---------------------------------
2652 running inside a non-init cgroup namespace::
2654 # mount -t cgroup2 none $MOUNT_POINT
2661 the view of cgroup hierarchy by namespace-private cgroupfs mount
2674 --------------------------------
2677 address_space_operations->writepage[s]() to annotate bio's using the
2694 super_block by setting SB_I_CGROUPWB in ->s_iflags. This allows for
2711 - Multiple hierarchies including named ones are not supported.
2713 - All v1 mount options are not supported.
2715 - The "tasks" file is removed and "cgroup.procs" is not sorted.
2717 - "cgroup.clone_children" is removed.
2719 - /proc/cgroups is meaningless for v2. Use "cgroup.controllers" file
2727 --------------------
2780 ------------------
2788 Generally, in-process knowledge is available only to the process
2789 itself; thus, unlike service-level organization of processes,
2796 sub-hierarchies and control resource distributions along them. This
2797 effectively raised cgroup to the status of a syscall-like API exposed
2807 that the process would actually be operating on its own sub-hierarchy.
2811 system-management pseudo filesystem. cgroup ended up with interface
2814 individual applications through the ill-defined delegation mechanism
2824 -------------------------------------------
2835 cycles and the number of internal threads fluctuated - the ratios
2851 clearly defined. There were attempts to add ad-hoc behaviors and
2865 ----------------------
2869 was how an empty cgroup was notified - a userland helper binary was
2872 to in-kernel event delivery filtering mechanism further complicating
2894 ------------------------------
2901 global reclaim prefers is opt-in, rather than opt-out. The costs for
2911 becomes self-defeating.
2913 The memory.low boundary on the other hand is a top-down allocated
2951 new limit is met - or the task writing to memory.max is killed.
2960 groups can sabotage swapping by other means - such as referencing its
2961 anonymous memory in a tight loop - and an admin can not assume full