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Diffstat (limited to 'Documentation/admin-guide/cgroup-v1/memory.rst')
| -rw-r--r-- | Documentation/admin-guide/cgroup-v1/memory.rst | 61 |
1 files changed, 22 insertions, 39 deletions
diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index 12757e63b26c..52688ae34461 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -77,6 +77,8 @@ Brief summary of control files. memory.soft_limit_in_bytes set/show soft limit of memory usage 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 memory.swappiness set/show swappiness parameter of vmscan @@ -285,20 +287,17 @@ When oom event notifier is registered, event will be delivered. 2.6 Locking ----------- - lock_page_cgroup()/unlock_page_cgroup() should not be called under - the i_pages lock. - - Other lock order is following: - - PG_locked. - mm->page_table_lock - pgdat->lru_lock - lock_page_cgroup. +Lock order is as follows: - In many cases, just lock_page_cgroup() is called. + Page lock (PG_locked bit of page->flags) + mm->page_table_lock or split pte_lock + lock_page_memcg (memcg->move_lock) + mapping->i_pages lock + lruvec->lru_lock. - per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by - pgdat->lru_lock, it has no lock of its own. +Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by +lruvec->lru_lock; PG_lru bit of page->flags is cleared before +isolating a page from its LRU under lruvec->lru_lock. 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM) ----------------------------------------------- @@ -495,16 +494,13 @@ 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 =================== @@ -527,8 +523,6 @@ About use_hierarchy, see Section 6. 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 ------------- @@ -675,31 +669,20 @@ 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 ------------------------------------------------- +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. -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:: +6.1 Hierarchical accounting and reclaim +--------------------------------------- - # echo 1 > memory.use_hierarchy - -The feature can be disabled by:: - - # echo 0 > memory.use_hierarchy +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. -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. +For compatibility reasons writing 1 to memory.use_hierarchy will always pass:: -NOTE2: - When panic_on_oom is set to "2", the whole system will panic in - case of an OOM event in any cgroup. + # echo 1 > memory.use_hierarchy 7. Soft limits ============== |