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Diffstat (limited to 'Documentation/admin-guide/cgroup-v1/memory.rst')
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1 files changed, 225 insertions, 266 deletions
diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index 0ae4f564c2d6..d6b1db8cc7eb 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -2,18 +2,18 @@ Memory Resource Controller ========================== -NOTE: +.. caution:: This document is hopelessly outdated and it asks for a complete rewrite. It still contains a useful information so we are keeping it here but make sure to check the current code if you need a deeper understanding. -NOTE: +.. note:: The Memory Resource Controller has generically been referred to as the memory controller in this document. Do not confuse memory controller used here with the memory controller that is used in hardware. -(For editors) In this document: +.. hint:: When we mention a cgroup (cgroupfs's directory) with memory controller, we call it "memory cgroup". When you see git-log and source code, you'll see patch's title and function names tend to use "memcg". @@ -23,7 +23,7 @@ Benefits and Purpose of the memory controller ============================================= The memory controller isolates the memory behaviour of a group of tasks -from the rest of the system. The article on LWN [12] mentions some probable +from the rest of the system. The article on LWN [12]_ mentions some probable uses of the memory controller. The memory controller can be used to a. Isolate an application or a group of applications @@ -55,7 +55,8 @@ Features: - Root cgroup has no limit controls. Kernel memory support is a work in progress, and the current version provides - basically functionality. (See Section 2.7) + basically functionality. (See :ref:`section 2.7 + <cgroup-v1-memory-kernel-extension>`) Brief summary of control files. @@ -64,6 +65,7 @@ Brief summary of control files. threads cgroup.procs show list of processes cgroup.event_control an interface for event_fd() + This knob is not available on CONFIG_PREEMPT_RT systems. memory.usage_in_bytes show current usage for memory (See 5.5 for details) memory.memsw.usage_in_bytes show current usage for memory+Swap @@ -75,46 +77,67 @@ Brief summary of control files. memory.max_usage_in_bytes show max memory usage recorded memory.memsw.max_usage_in_bytes show max memory+Swap usage recorded memory.soft_limit_in_bytes set/show soft limit of memory usage + This knob is not available on CONFIG_PREEMPT_RT systems. + This knob is deprecated and shouldn't be + used. memory.stat show various statistics memory.use_hierarchy set/show hierarchical account enabled + This knob is deprecated and shouldn't be + used. memory.force_empty trigger forced page reclaim memory.pressure_level set memory pressure notifications + This knob is deprecated and shouldn't be + used. memory.swappiness set/show swappiness parameter of vmscan (See sysctl's vm.swappiness) - memory.move_charge_at_immigrate set/show controls of moving charges + Per memcg knob does not exist in cgroup v2. + memory.move_charge_at_immigrate This knob is deprecated. memory.oom_control set/show oom controls. + This knob is deprecated and shouldn't be + used. memory.numa_stat show the number of memory usage per numa node - memory.kmem.limit_in_bytes set/show hard limit for kernel memory - This knob is deprecated and shouldn't be - used. It is planned that this be removed in - the foreseeable future. + memory.kmem.limit_in_bytes Deprecated knob to set and read the kernel + memory hard limit. Kernel hard limit is not + supported since 5.16. Writing any value to + do file will not have any effect same as if + nokmem kernel parameter was specified. + Kernel memory is still charged and reported + by memory.kmem.usage_in_bytes. memory.kmem.usage_in_bytes show current kernel memory allocation memory.kmem.failcnt show the number of kernel memory usage hits limits memory.kmem.max_usage_in_bytes show max kernel memory usage recorded memory.kmem.tcp.limit_in_bytes set/show hard limit for tcp buf memory + This knob is deprecated and shouldn't be + used. memory.kmem.tcp.usage_in_bytes show current tcp buf memory allocation + This knob is deprecated and shouldn't be + used. memory.kmem.tcp.failcnt show the number of tcp buf memory usage hits limits + This knob is deprecated and shouldn't be + used. memory.kmem.tcp.max_usage_in_bytes show max tcp buf memory usage recorded + This knob is deprecated and shouldn't be + used. ==================================== ========================================== 1. History ========== The memory controller has a long history. A request for comments for the memory -controller was posted by Balbir Singh [1]. At the time the RFC was posted +controller was posted by Balbir Singh [1]_. At the time the RFC was posted there were several implementations for memory control. The goal of the RFC was to build consensus and agreement for the minimal features required -for memory control. The first RSS controller was posted by Balbir Singh[2] -in Feb 2007. Pavel Emelianov [3][4][5] has since posted three versions of the -RSS controller. At OLS, at the resource management BoF, everyone suggested -that we handle both page cache and RSS together. Another request was raised -to allow user space handling of OOM. The current memory controller is +for memory control. The first RSS controller was posted by Balbir Singh [2]_ +in Feb 2007. Pavel Emelianov [3]_ [4]_ [5]_ has since posted three versions +of the RSS controller. At OLS, at the resource management BoF, everyone +suggested that we handle both page cache and RSS together. Another request was +raised to allow user space handling of OOM. The current memory controller is at version 6; it combines both mapped (RSS) and unmapped Page -Cache Control [11]. +Cache Control [11]_. 2. Memory Control ================= @@ -145,7 +168,8 @@ specific data structure (mem_cgroup) associated with it. 2.2. Accounting --------------- -:: +.. code-block:: + :caption: Figure 1: Hierarchy of Accounting +--------------------+ | mem_cgroup | @@ -165,7 +189,6 @@ specific data structure (mem_cgroup) associated with it. | | | | +---------------+ +---------------+ - (Figure 1: Hierarchy of Accounting) Figure 1 shows the important aspects of the controller @@ -192,18 +215,18 @@ are not accounted. We just account pages under usual VM management. RSS pages are accounted at page_fault unless they've already been accounted for earlier. A file page will be accounted for as Page Cache when it's -inserted into inode (radix-tree). While it's mapped into the page tables of +inserted into inode (xarray). While it's mapped into the page tables of processes, duplicate accounting is carefully avoided. An RSS page is unaccounted when it's fully unmapped. A PageCache page is -unaccounted when it's removed from radix-tree. Even if RSS pages are fully +unaccounted when it's removed from xarray. Even if RSS pages are fully unmapped (by kswapd), they may exist as SwapCache in the system until they are really freed. Such SwapCaches are also accounted. -A swapped-in page is not accounted until it's mapped. +A swapped-in page is accounted after adding into swapcache. Note: The kernel does swapin-readahead and reads multiple swaps at once. -This means swapped-in pages may contain pages for other tasks than a task -causing page fault. So, we avoid accounting at swap-in I/O. +Since page's memcg recorded into swap whatever memsw enabled, the page will +be accounted after swapin. At page migration, accounting information is kept. @@ -219,21 +242,13 @@ behind this approach is that a cgroup that aggressively uses a shared page will eventually get charged for it (once it is uncharged from the cgroup that brought it in -- this will happen on memory pressure). -But see section 8.2: when moving a task to another cgroup, its pages may -be recharged to the new cgroup, if move_charge_at_immigrate has been chosen. - -Exception: If CONFIG_MEMCG_SWAP is not used. -When you do swapoff and make swapped-out pages of shmem(tmpfs) to -be backed into memory in force, charges for pages are accounted against the -caller of swapoff rather than the users of shmem. - -2.4 Swap Extension (CONFIG_MEMCG_SWAP) +2.4 Swap Extension -------------------------------------- -Swap Extension allows you to record charge for swap. A swapped-in page is -charged back to original page allocator if possible. +Swap usage is always recorded for each of cgroup. Swap Extension allows you to +read and limit it. -When swap is accounted, following files are added. +When CONFIG_SWAP is enabled, following files are added. - memory.memsw.usage_in_bytes. - memory.memsw.limit_in_bytes. @@ -247,7 +262,8 @@ In this case, setting memsw.limit_in_bytes=3G will prevent bad use of swap. By using the memsw limit, you can avoid system OOM which can be caused by swap shortage. -**why 'memory+swap' rather than swap** +2.4.1 why 'memory+swap' rather than swap +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The global LRU(kswapd) can swap out arbitrary pages. Swap-out means to move account from memory to swap...there is no change in usage of @@ -255,7 +271,8 @@ memory+swap. In other words, when we want to limit the usage of swap without affecting global LRU, memory+swap limit is better than just limiting swap from an OS point of view. -**What happens when a cgroup hits memory.memsw.limit_in_bytes** +2.4.2. What happens when a cgroup hits memory.memsw.limit_in_bytes +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When a cgroup hits memory.memsw.limit_in_bytes, it's useless to do swap-out in this cgroup. Then, swap-out will not be done by cgroup routine and file @@ -271,41 +288,40 @@ global VM. When a cgroup goes over its limit, we first try to reclaim memory from the cgroup so as to make space for the new pages that the cgroup has touched. If the reclaim is unsuccessful, an OOM routine is invoked to select and kill the bulkiest task in the -cgroup. (See 10. OOM Control below.) +cgroup. (See :ref:`10. OOM Control <cgroup-v1-memory-oom-control>` below.) The reclaim algorithm has not been modified for cgroups, except that pages that are selected for reclaiming come from the per-cgroup LRU list. -NOTE: - Reclaim does not work for the root cgroup, since we cannot set any - limits on the root cgroup. +.. note:: + Reclaim does not work for the root cgroup, since we cannot set any + limits on the root cgroup. -Note2: - When panic_on_oom is set to "2", the whole system will panic. +.. note:: + When panic_on_oom is set to "2", the whole system will panic. When oom event notifier is registered, event will be delivered. -(See oom_control section) +(See :ref:`oom_control <cgroup-v1-memory-oom-control>` section) 2.6 Locking ----------- - lock_page_cgroup()/unlock_page_cgroup() should not be called under - the i_pages lock. +Lock order is as follows:: - Other lock order is following: + folio_lock + mm->page_table_lock or split pte_lock + folio_memcg_lock (memcg->move_lock) + mapping->i_pages lock + lruvec->lru_lock. - PG_locked. - mm->page_table_lock - pgdat->lru_lock - lock_page_cgroup. +Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by +lruvec->lru_lock; the folio LRU flag is cleared before +isolating a page from its LRU under lruvec->lru_lock. - In many cases, just lock_page_cgroup() is called. +.. _cgroup-v1-memory-kernel-extension: - per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by - pgdat->lru_lock, it has no lock of its own. - -2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM) +2.7 Kernel Memory Extension ----------------------------------------------- With the Kernel memory extension, the Memory Controller is able to limit @@ -366,17 +382,17 @@ U != 0, K = unlimited: U != 0, K < U: Kernel memory is a subset of the user memory. This setup is useful in - deployments where the total amount of memory per-cgroup is overcommited. - Overcommiting kernel memory limits is definitely not recommended, since the + deployments where the total amount of memory per-cgroup is overcommitted. + Overcommitting kernel memory limits is definitely not recommended, since the box can still run out of non-reclaimable memory. In this case, the admin could set up K so that the sum of all groups is never greater than the total memory, and freely set U at the cost of his QoS. -WARNING: - In the current implementation, memory reclaim will NOT be - triggered for a cgroup when it hits K while staying below U, which makes - this setup impractical. + .. warning:: + In the current implementation, memory reclaim will NOT be triggered for + a cgroup when it hits K while staying below U, which makes this setup + impractical. U != 0, K >= U: Since kmem charges will also be fed to the user counter and reclaim will be @@ -387,47 +403,41 @@ U != 0, K >= U: 3. User Interface ================= -3.0. Configuration ------------------- - -a. Enable CONFIG_CGROUPS -b. Enable CONFIG_MEMCG -c. Enable CONFIG_MEMCG_SWAP (to use swap extension) -d. Enable CONFIG_MEMCG_KMEM (to use kmem extension) +To use the user interface: -3.1. Prepare the cgroups (see cgroups.txt, Why are cgroups needed?) -------------------------------------------------------------------- - -:: +1. Enable CONFIG_CGROUPS and CONFIG_MEMCG options +2. Prepare the cgroups (see :ref:`Why are cgroups needed? + <cgroups-why-needed>` for the background information):: # mount -t tmpfs none /sys/fs/cgroup # mkdir /sys/fs/cgroup/memory # mount -t cgroup none /sys/fs/cgroup/memory -o memory -3.2. Make the new group and move bash into it:: +3. Make the new group and move bash into it:: # mkdir /sys/fs/cgroup/memory/0 # echo $$ > /sys/fs/cgroup/memory/0/tasks -Since now we're in the 0 cgroup, we can alter the memory limit:: +4. Since now we're in the 0 cgroup, we can alter the memory limit:: # echo 4M > /sys/fs/cgroup/memory/0/memory.limit_in_bytes -NOTE: - We can use a suffix (k, K, m, M, g or G) to indicate values in kilo, - mega or gigabytes. (Here, Kilo, Mega, Giga are Kibibytes, Mebibytes, - Gibibytes.) + The limit can now be queried:: + + # cat /sys/fs/cgroup/memory/0/memory.limit_in_bytes + 4194304 -NOTE: - We can write "-1" to reset the ``*.limit_in_bytes(unlimited)``. +.. note:: + We can use a suffix (k, K, m, M, g or G) to indicate values in kilo, + mega or gigabytes. (Here, Kilo, Mega, Giga are Kibibytes, Mebibytes, + Gibibytes.) -NOTE: - We cannot set limits on the root cgroup any more. +.. note:: + We can write "-1" to reset the ``*.limit_in_bytes(unlimited)``. -:: +.. note:: + We cannot set limits on the root cgroup any more. - # cat /sys/fs/cgroup/memory/0/memory.limit_in_bytes - 4194304 We can check the usage:: @@ -466,6 +476,8 @@ test because it has noise of shared objects/status. But the above two are testing extreme situations. Trying usual test under memory controller is always helpful. +.. _cgroup-v1-memory-test-troubleshoot: + 4.1 Troubleshooting ------------------- @@ -478,8 +490,11 @@ terminated by the OOM killer. There are several causes for this: A sync followed by echo 1 > /proc/sys/vm/drop_caches will help get rid of some of the pages cached in the cgroup (page cache pages). -To know what happens, disabling OOM_Kill as per "10. OOM Control" (below) and -seeing what happens will be helpful. +To know what happens, disabling OOM_Kill as per :ref:`"10. OOM Control" +<cgroup-v1-memory-oom-control>` (below) and seeing what happens will be +helpful. + +.. _cgroup-v1-memory-test-task-migration: 4.2 Task migration ------------------ @@ -490,26 +505,24 @@ remain charged to it, the charge is dropped when the page is freed or reclaimed. You can move charges of a task along with task migration. -See 8. "Move charges at task migration" +See :ref:`8. "Move charges at task migration" <cgroup-v1-memory-move-charges>` 4.3 Removing a cgroup --------------------- -A cgroup can be removed by rmdir, but as discussed in sections 4.1 and 4.2, a -cgroup might have some charge associated with it, even though all -tasks have migrated away from it. (because we charge against pages, not -against tasks.) +A cgroup can be removed by rmdir, but as discussed in :ref:`sections 4.1 +<cgroup-v1-memory-test-troubleshoot>` and :ref:`4.2 +<cgroup-v1-memory-test-task-migration>`, a cgroup might have some charge +associated with it, even though all tasks have migrated away from it. (because +we charge against pages, not against tasks.) -We move the stats to root (if use_hierarchy==0) or parent (if -use_hierarchy==1), and no change on the charge except uncharging +We move the stats to parent, and no change on the charge except uncharging from the child. Charges recorded in swap information is not updated at removal of cgroup. Recorded information is discarded and a cgroup which uses swap (swapcache) will be charged as a new owner of it. -About use_hierarchy, see Section 6. - 5. Misc. interfaces =================== @@ -527,82 +540,80 @@ About use_hierarchy, see Section 6. charged file caches. Some out-of-use page caches may keep charged until memory pressure happens. If you want to avoid that, force_empty will be useful. - Also, note that when memory.kmem.limit_in_bytes is set the charges due to - kernel pages will still be seen. This is not considered a failure and the - write will still return success. In this case, it is expected that - memory.kmem.usage_in_bytes == memory.usage_in_bytes. - - About use_hierarchy, see Section 6. - 5.2 stat file ------------- -memory.stat file includes following statistics - -per-memory cgroup local status -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -=============== =============================================================== -cache # of bytes of page cache memory. -rss # of bytes of anonymous and swap cache memory (includes - transparent hugepages). -rss_huge # of bytes of anonymous transparent hugepages. -mapped_file # of bytes of mapped file (includes tmpfs/shmem) -pgpgin # of charging events to the memory cgroup. The charging - event happens each time a page is accounted as either mapped - anon page(RSS) or cache page(Page Cache) to the cgroup. -pgpgout # of uncharging events to the memory cgroup. The uncharging - event happens each time a page is unaccounted from the cgroup. -swap # of bytes of swap usage -dirty # of bytes that are waiting to get written back to the disk. -writeback # of bytes of file/anon cache that are queued for syncing to - disk. -inactive_anon # of bytes of anonymous and swap cache memory on inactive - LRU list. -active_anon # of bytes of anonymous and swap cache memory on active - LRU list. -inactive_file # of bytes of file-backed memory on inactive LRU list. -active_file # of bytes of file-backed memory on active LRU list. -unevictable # of bytes of memory that cannot be reclaimed (mlocked etc). -=============== =============================================================== - -status considering hierarchy (see memory.use_hierarchy settings) -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -========================= =================================================== -hierarchical_memory_limit # of bytes of memory limit with regard to hierarchy - under which the memory cgroup is -hierarchical_memsw_limit # of bytes of memory+swap limit with regard to - hierarchy under which memory cgroup is. - -total_<counter> # hierarchical version of <counter>, which in - addition to the cgroup's own value includes the - sum of all hierarchical children's values of - <counter>, i.e. total_cache -========================= =================================================== - -The following additional stats are dependent on CONFIG_DEBUG_VM -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -========================= ======================================== -recent_rotated_anon VM internal parameter. (see mm/vmscan.c) -recent_rotated_file VM internal parameter. (see mm/vmscan.c) -recent_scanned_anon VM internal parameter. (see mm/vmscan.c) -recent_scanned_file VM internal parameter. (see mm/vmscan.c) -========================= ======================================== - -Memo: +memory.stat file includes following statistics: + + * per-memory cgroup local status + + =============== =============================================================== + cache # of bytes of page cache memory. + rss # of bytes of anonymous and swap cache memory (includes + transparent hugepages). + rss_huge # of bytes of anonymous transparent hugepages. + mapped_file # of bytes of mapped file (includes tmpfs/shmem) + pgpgin # of charging events to the memory cgroup. The charging + event happens each time a page is accounted as either mapped + anon page(RSS) or cache page(Page Cache) to the cgroup. + pgpgout # of uncharging events to the memory cgroup. The uncharging + event happens each time a page is unaccounted from the + cgroup. + swap # of bytes of swap usage + swapcached # of bytes of swap cached in memory + dirty # of bytes that are waiting to get written back to the disk. + writeback # of bytes of file/anon cache that are queued for syncing to + disk. + inactive_anon # of bytes of anonymous and swap cache memory on inactive + LRU list. + active_anon # of bytes of anonymous and swap cache memory on active + LRU list. + inactive_file # of bytes of file-backed memory and MADV_FREE anonymous + memory (LazyFree pages) on inactive LRU list. + active_file # of bytes of file-backed memory on active LRU list. + unevictable # of bytes of memory that cannot be reclaimed (mlocked etc). + =============== =============================================================== + + * status considering hierarchy (see memory.use_hierarchy settings): + + ========================= =================================================== + hierarchical_memory_limit # of bytes of memory limit with regard to + hierarchy + under which the memory cgroup is + hierarchical_memsw_limit # of bytes of memory+swap limit with regard to + hierarchy under which memory cgroup is. + + total_<counter> # hierarchical version of <counter>, which in + addition to the cgroup's own value includes the + sum of all hierarchical children's values of + <counter>, i.e. total_cache + ========================= =================================================== + + * additional vm parameters (depends on CONFIG_DEBUG_VM): + + ========================= ======================================== + recent_rotated_anon VM internal parameter. (see mm/vmscan.c) + recent_rotated_file VM internal parameter. (see mm/vmscan.c) + recent_scanned_anon VM internal parameter. (see mm/vmscan.c) + recent_scanned_file VM internal parameter. (see mm/vmscan.c) + ========================= ======================================== + +.. hint:: recent_rotated means recent frequency of LRU rotation. recent_scanned means recent # of scans to LRU. showing for better debug please see the code for meanings. -Note: +.. note:: Only anonymous and swap cache memory is listed as part of 'rss' stat. This should not be confused with the true 'resident set size' or the amount of physical memory used by the cgroup. 'rss + mapped_file" will give you resident set size of cgroup. + Note that some kernel configurations might account complete larger + allocations (e.g., THP) towards 'rss' and 'mapped_file', even if + only some, but not all that memory is mapped. + (Note: file and shmem may be shared among other cgroups. In that case, mapped_file is accounted only when the memory cgroup is owner of page cache.) @@ -680,34 +691,25 @@ hierarchy:: d e In the diagram above, with hierarchical accounting enabled, all memory -usage of e, is accounted to its ancestors up until the root (i.e, c and root), -that has memory.use_hierarchy enabled. If one of the ancestors goes over its -limit, the reclaim algorithm reclaims from the tasks in the ancestor and the -children of the ancestor. - -6.1 Enabling hierarchical accounting and reclaim ------------------------------------------------- - -A memory cgroup by default disables the hierarchy feature. Support -can be enabled by writing 1 to memory.use_hierarchy file of the root cgroup:: +usage of e, is accounted to its ancestors up until the root (i.e, c and root). +If one of the ancestors goes over its limit, the reclaim algorithm reclaims +from the tasks in the ancestor and the children of the ancestor. - # echo 1 > memory.use_hierarchy +6.1 Hierarchical accounting and reclaim +--------------------------------------- -The feature can be disabled by:: +Hierarchical accounting is enabled by default. Disabling the hierarchical +accounting is deprecated. An attempt to do it will result in a failure +and a warning printed to dmesg. - # echo 0 > memory.use_hierarchy +For compatibility reasons writing 1 to memory.use_hierarchy will always pass:: -NOTE1: - Enabling/disabling will fail if either the cgroup already has other - cgroups created below it, or if the parent cgroup has use_hierarchy - enabled. + # echo 1 > memory.use_hierarchy -NOTE2: - When panic_on_oom is set to "2", the whole system will panic in - case of an OOM event in any cgroup. +7. Soft limits (DEPRECATED) +=========================== -7. Soft limits -============== +THIS IS DEPRECATED! Soft limits allow for greater sharing of memory. The idea behind soft limits is to allow control groups to use as much of the memory as needed, provided @@ -738,77 +740,23 @@ If we want to change this to 1G, we can at any time use:: # echo 1G > memory.soft_limit_in_bytes -NOTE1: +.. note:: Soft limits take effect over a long period of time, since they involve reclaiming memory for balancing between memory cgroups -NOTE2: + +.. note:: It is recommended to set the soft limit always below the hard limit, otherwise the hard limit will take precedence. -8. Move charges at task migration -================================= - -Users can move charges associated with a task along with task migration, that -is, uncharge task's pages from the old cgroup and charge them to the new cgroup. -This feature is not supported in !CONFIG_MMU environments because of lack of -page tables. - -8.1 Interface -------------- - -This feature is disabled by default. It can be enabled (and disabled again) by -writing to memory.move_charge_at_immigrate of the destination cgroup. - -If you want to enable it:: +.. _cgroup-v1-memory-move-charges: - # echo (some positive value) > memory.move_charge_at_immigrate +8. Move charges at task migration (DEPRECATED!) +=============================================== -Note: - Each bits of move_charge_at_immigrate has its own meaning about what type - of charges should be moved. See 8.2 for details. -Note: - Charges are moved only when you move mm->owner, in other words, - a leader of a thread group. -Note: - If we cannot find enough space for the task in the destination cgroup, we - try to make space by reclaiming memory. Task migration may fail if we - cannot make enough space. -Note: - It can take several seconds if you move charges much. +THIS IS DEPRECATED! -And if you want disable it again:: - - # echo 0 > memory.move_charge_at_immigrate - -8.2 Type of charges which can be moved --------------------------------------- - -Each bit in move_charge_at_immigrate has its own meaning about what type of -charges should be moved. But in any case, it must be noted that an account of -a page or a swap can be moved only when it is charged to the task's current -(old) memory cgroup. - -+---+--------------------------------------------------------------------------+ -|bit| what type of charges would be moved ? | -+===+==========================================================================+ -| 0 | A charge of an anonymous page (or swap of it) used by the target task. | -| | You must enable Swap Extension (see 2.4) to enable move of swap charges. | -+---+--------------------------------------------------------------------------+ -| 1 | A charge of file pages (normal file, tmpfs file (e.g. ipc shared memory) | -| | and swaps of tmpfs file) mmapped by the target task. Unlike the case of | -| | anonymous pages, file pages (and swaps) in the range mmapped by the task | -| | will be moved even if the task hasn't done page fault, i.e. they might | -| | not be the task's "RSS", but other task's "RSS" that maps the same file. | -| | And mapcount of the page is ignored (the page can be moved even if | -| | page_mapcount(page) > 1). You must enable Swap Extension (see 2.4) to | -| | enable move of swap charges. | -+---+--------------------------------------------------------------------------+ - -8.3 TODO --------- - -- All of moving charge operations are done under cgroup_mutex. It's not good - behavior to hold the mutex too long, so we may need some trick. +Reading memory.move_charge_at_immigrate will always return 0 and writing +to it will always return -EINVAL. 9. Memory thresholds ==================== @@ -829,8 +777,12 @@ threshold in any direction. It's applicable for root and non-root cgroup. -10. OOM Control -=============== +.. _cgroup-v1-memory-oom-control: + +10. OOM Control (DEPRECATED) +============================ + +THIS IS DEPRECATED! memory.oom_control file is for OOM notification and other controls. @@ -873,9 +825,14 @@ At reading, current status of OOM is shown. (if 1, oom-killer is disabled) - under_oom 0 or 1 (if 1, the memory cgroup is under OOM, tasks may be stopped.) + - oom_kill integer counter + The number of processes belonging to this cgroup killed by any + kind of OOM killer. -11. Memory Pressure -=================== +11. Memory Pressure (DEPRECATED) +================================ + +THIS IS DEPRECATED! The pressure level notifications can be used to monitor the memory allocation cost; based on the pressure, applications can implement @@ -907,7 +864,7 @@ experiences some pressure. In this situation, only group C will receive the notification, i.e. groups A and B will not receive it. This is done to avoid excessive "broadcasting" of messages, which disturbs the system and which is especially bad if we are low on memory or thrashing. Group B, will receive -notification only if there are no event listers for group C. +notification only if there are no event listeners for group C. There are three optional modes that specify different propagation behavior: @@ -981,25 +938,27 @@ commented and discussed quite extensively in the community. References ========== -1. Singh, Balbir. RFC: Memory Controller, http://lwn.net/Articles/206697/ -2. Singh, Balbir. Memory Controller (RSS Control), +.. [1] Singh, Balbir. RFC: Memory Controller, http://lwn.net/Articles/206697/ +.. [2] Singh, Balbir. Memory Controller (RSS Control), http://lwn.net/Articles/222762/ -3. Emelianov, Pavel. Resource controllers based on process cgroups - http://lkml.org/lkml/2007/3/6/198 -4. Emelianov, Pavel. RSS controller based on process cgroups (v2) - http://lkml.org/lkml/2007/4/9/78 -5. Emelianov, Pavel. RSS controller based on process cgroups (v3) - http://lkml.org/lkml/2007/5/30/244 +.. [3] Emelianov, Pavel. Resource controllers based on process cgroups + https://lore.kernel.org/r/45ED7DEC.7010403@sw.ru +.. [4] Emelianov, Pavel. RSS controller based on process cgroups (v2) + https://lore.kernel.org/r/461A3010.90403@sw.ru +.. [5] Emelianov, Pavel. RSS controller based on process cgroups (v3) + https://lore.kernel.org/r/465D9739.8070209@openvz.org + 6. Menage, Paul. Control Groups v10, http://lwn.net/Articles/236032/ 7. Vaidyanathan, Srinivasan, Control Groups: Pagecache accounting and control subsystem (v3), http://lwn.net/Articles/235534/ 8. Singh, Balbir. RSS controller v2 test results (lmbench), - http://lkml.org/lkml/2007/5/17/232 + https://lore.kernel.org/r/464C95D4.7070806@linux.vnet.ibm.com 9. Singh, Balbir. RSS controller v2 AIM9 results - http://lkml.org/lkml/2007/5/18/1 + https://lore.kernel.org/r/464D267A.50107@linux.vnet.ibm.com 10. Singh, Balbir. Memory controller v6 test results, - http://lkml.org/lkml/2007/8/19/36 -11. Singh, Balbir. Memory controller introduction (v6), - http://lkml.org/lkml/2007/8/17/69 -12. Corbet, Jonathan, Controlling memory use in cgroups, - http://lwn.net/Articles/243795/ + https://lore.kernel.org/r/20070819094658.654.84837.sendpatchset@balbir-laptop + +.. [11] Singh, Balbir. Memory controller introduction (v6), + https://lore.kernel.org/r/20070817084228.26003.12568.sendpatchset@balbir-laptop +.. [12] Corbet, Jonathan, Controlling memory use in cgroups, + http://lwn.net/Articles/243795/ |