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Suren Baghdasaryan 51ee4c505f lmkd: add kill when swap utilization is too high 
When non-swappable allocations cause memory pressure swap will not be
depleted, however a high percentage of the swappable memory will be
pushed into swap. Detect this condition and kill a process when swap
utilization is too high while under memory pressure.
Introduce ro.lmk.swap_util_max property to represent max percentage of
the overall swappable memory that can be swapped under memory pressure
without triggering a kill. ro.lmk.swap_util_max is set to 100 by default
which disables kills due to the swap utilization.

Bug: 147315292
Test: ION memory hogger with ro.lmk.swap_util_max set to 95
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I6dbf124bb24b220d136e8f16b3dae0c0c30d32ca
 		2020-04-29 15:11:02 -07:00
include lmkd: Restrict lmkd unsolicited notifications only to subscribed recipients 2019-12-23 12:35:29 -08:00
libpsi Include what you use: <stdio.h> and <unistd.h> 2020-04-13 15:21:09 -07:00
tests lmkd_test: set process types 2020-03-09 13:17:51 +08:00
Android.bp Link libstatssocket as a shared library. 2020-02-12 16:42:53 -08:00
OWNERS Add lmkd/OWNERS. 2017-12-08 16:12:58 -08:00
README.md lmkd: Support to send unsolicited message to clients 2019-12-12 08:53:04 -08:00
event.logtags lmkd: Change meminfo_log into killinfo_log and log additional fields 2019-10-01 23:26:56 +00:00
liblmkd_utils.cpp Build lmkd as C++ 2019-12-13 08:40:30 -08:00
lmkd.cpp lmkd: add kill when swap utilization is too high 2020-04-29 15:11:02 -07:00
lmkd.rc lmkd: Restrict process record modifications to the client that created it 2019-11-07 18:15:04 +00:00
statslog.cpp Include what you use: <stdio.h> and <unistd.h> 2020-04-13 15:21:09 -07:00
statslog.h Use generated code for logging events to statsd 2020-01-13 12:16:47 -08:00

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

ro.lmk.psi_partial_stall_ms: partial PSI stall threshold in milliseconds for triggering low memory notification. Default for low-RAM devices = 200, for high-end devices = 70

ro.lmk.psi_complete_stall_ms: complete PSI stall threshold in milliseconds for triggering critical memory notification. Default = 700

lmkd will set the following Android properties according to current system configurations:

sys.lmk.minfree_levels: minfree:oom_adj_score pairs, delimited by comma

sys.lmk.reportkills: whether or not it supports reporting process kills to clients. Test app should check this property before testing low memory kill notification. Default will be unset.