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Suren Baghdasaryan fe26dfb3bf lmkd: Do not set soft_limit_in_bytes on high-end devices 
Setting memory.soft_limit_in_bytes on high-end devices with large memory
reserves affects performance of memory-hungry applications that have
large workingsets and keep thrashing because of the memory limits imposed.
Limit the usage of memory.soft_limit_in_bytes to low-memory devices only.
Add debug messages for future troubleshooting to capture cases when
vmpressure events are being ignored.

Bug: 78916015
Test: collect vmstat while running a heavy app
Change-Id: Ib4434b96d2be802ef89960b573486eae8d12f198
Merged-In: Ib4434b96d2be802ef89960b573486eae8d12f198
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
 		2018-05-22 10:25:38 -07:00
..
include lmkd: Introduce liblmkd_utils for communicating with lmkd process 2018-03-09 11:18:53 -08:00
tests lmkd: test: access /sys/module/lowmemorykiller/ as u:r:shell:s0 2018-04-03 14:41:11 +00:00
Android.bp lmkd: only mlockall() if enabled 2018-04-03 14:41:26 +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 2018-04-15 16:02:36 +00:00
liblmkd_utils.c lmkd: Introduce liblmkd_utils for communicating with lmkd process 2018-03-09 11:18:53 -08:00
lmkd.c lmkd: Do not set soft_limit_in_bytes on high-end devices 2018-05-22 10:25:38 -07:00
lmkd.rc lmkd: limit capability set to minimum 2018-04-16 14:51:56 -07:00

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