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Juju Sung 1d982ded6f lmkd: Remove redundant free swap and free memory check 
lmkd can't kill processes because it has compare the size between free swap and free memory. Free swap is often larger than the free memory when system is under low memory with less swap-backed or swappable pages and finally leads to I/O thrashing.

Test: TreeHugger
Bug: 124727769
Change-Id: Ia2848859aa97a24bd13c704acee4b86cd2d3f647
 		2019-02-19 17:04:07 +00:00
..
include Make inlines static 2019-02-06 15:19:00 -08:00
libpsi libpsi: initial revision 2019-01-30 04:47:28 +00:00
tests lmkd: add missing libcutils library to test 2019-01-15 14:14:20 -08:00
Android.bp lmkd: Add support for psi monitors 2019-02-01 18:40:32 +00:00
OWNERS Add lmkd/OWNERS. 2017-12-08 16:12:58 -08:00
README.md lmkd: Introduce support for legacy kill algorithm that uses minfree levels 2018-04-17 01:42:06 +00:00
event.logtags lmkd: Add meminfo logging after each kill for easy troubleshooting 2018-08-10 14:21:31 -07:00
liblmkd_utils.c lmkd: Introduce liblmkd_utils for communicating with lmkd process 2018-03-09 11:18:53 -08:00
lmkd.c lmkd: Remove redundant free swap and free memory check 2019-02-19 17:04:07 +00:00
lmkd.rc lmkd: limit capability set to minimum 2018-04-16 14:51:56 -07:00
statslog.c Add start time to LmkKillOccurred 2019-01-04 11:36:54 +00:00
statslog.h Add start time to LmkKillOccurred 2019-01-04 11:36:54 +00:00

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