81c75b2a33
Parsing /proc/zoneinfo is expensive and zone watermarks normally do no change often. Instead of checking free memory per each zone we aggregate zone watermarks and compare them with MemFree from meminfo as an approximation of memory being under a given watermark. zoneinfo parsing is rate limited to once per minute to detect a possible change of the memory margins from userspace. Bug: 132642304 Test: lmkd_unit_test, ACT memory pressure tests Change-Id: If4a8154c004e24324e6de44359de416766139df6 Signed-off-by: Suren Baghdasaryan <surenb@google.com> |
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| include | ||
| libpsi | ||
| tests | ||
| Android.bp | ||
| OWNERS | ||
| README.md | ||
| event.logtags | ||
| liblmkd_utils.c | ||
| lmkd.c | ||
| lmkd.rc | ||
| statslog.c | ||
| statslog.h | ||
README.md
Android Low Memory Killer Daemon
Introduction
Android Low Memory Killer Daemon (lmkd) is a process monitoring memory state of a running Android system and reacting to high memory pressure by killing the least essential process(es) to keep system performing at acceptable levels.
Background
Historically on Android systems memory monitoring and killing of non-essential processes was handled by a kernel lowmemorykiller driver. Since Linux Kernel 4.12 the lowmemorykiller driver has been removed and instead userspace lmkd daemon performs these tasks.
Android Properties
lmkd can be configured on a particular system using the following Android properties:
ro.config.low_ram: choose between low-memory vs high-performance device. Default = false.
ro.lmk.use_minfree_levels: use free memory and file cache thresholds for making decisions when to kill. This mode works the same way kernel lowmemorykiller driver used to work. Default = false
ro.lmk.low: min oom_adj score for processes eligible to be killed at low vmpressure level. Default = 1001 (disabled)
ro.lmk.medium: min oom_adj score for processes eligible to be killed at medium vmpressure level. Default = 800 (non-essential processes)
ro.lmk.critical: min oom_adj score for processes eligible to be killed at critical vmpressure level. Default = 0 (all processes)
ro.lmk.critical_upgrade: enables upgrade to critical level. Default = false
ro.lmk.upgrade_pressure: max mem_pressure at which level will be upgraded because system is swapping too much. Default = 100 (disabled)
ro.lmk.downgrade_pressure: min mem_pressure at which vmpressure event will be ignored because enough free memory is still available. Default = 100 (disabled)
ro.lmk.kill_heaviest_task: kill heaviest eligible task (best decision) vs. any eligible task (fast decision). Default = false
ro.lmk.kill_timeout_ms: duration in ms after a kill when no additional kill will be done. Default = 0 (disabled)
ro.lmk.debug: enable lmkd debug logs, Default = false
ro.lmk.swap_free_low_percentage: level of free swap as a percentage of the total swap space used as a threshold to consider the system as swap space starved. Default for low-RAM devices = 10, for high-end devices = 20
ro.lmk.thrashing_limit: number of workingset refaults as a percentage of the file-backed pagecache size used as a threshold to consider system thrashing its pagecache. Default for low-RAM devices = 30, for high-end devices = 100
ro.lmk.thrashing_limit_decay: thrashing threshold decay expressed as a percentage of the original threshold used to lower the threshold when system does not recover even after a kill. Default for low-RAM devices = 50, for high-end devices = 10