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Suren Baghdasaryan 03cb836735 lmkd: Change procfs read routine to handle files larger than 1 page in size 
Files like /proc/zoneinfo or /proc/<pid>/status can be larger than 4KB
page size. Change reread_file routine to resize read buffer whenever
it is not big enough to read the entire file. Start with 1-page buffer
and double its size until it's big enough to read the entire file.
Read /proc/zoneinfo during initialization to initialize the buffer
to a big enough size and avoid re-allocations when under memory pressure.

Bug: 137010962
Test: lmkd_unit_test
Change-Id: If9a5b0d27c2f4de9063f0fd0f36f908ece87dcce
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
 		2019-09-30 16:53:18 +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 2018-04-15 16:02:36 +00:00
event.logtags lmkd: Fix meminfo logs missing SwapTotal and having wrong field order 2019-03-25 11:04:11 -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: Change procfs read routine to handle files larger than 1 page in size 2019-09-30 16:53:18 +00:00
lmkd.rc lmkd: limit capability set to minimum 2018-04-16 14:51:56 -07:00
statslog.c lmkd: Maintain pid to taskname mapping to amend kill reports. 2019-09-26 16:27:03 -07:00
statslog.h lmkd: Maintain pid to taskname mapping to amend kill reports. 2019-09-26 16:27:03 -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