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With new psi monitor support in the kernel lmkd can use it to register custom pressure levels. Add lmkd support for psi monitors when they are provided by the kernel and use them by default. When kernel does not support psi lmkd will fall back to vmpressure usage. Add ability to poll memory status after the initial psi event is triggered because kernel throttles psi memory pressure events to one per PSI tracking window (currently set to 1sec). Current implementation polls every 200ms for 1sec duration after the initial event is triggered. If ro.lmk.use_psi is set to false psi logic will be disabled even when psi is supported in kernel. Bug: 111308141 Test: lmkd_unit_test Change-Id: I685774b176f393bab7412161773f5c9af51e0163 Signed-off-by: Suren Baghdasaryan <surenb@google.com> |
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| .. | ||
| include | ||
| libpsi | ||
| tests | ||
| Android.bp | ||
| event.logtags | ||
| liblmkd_utils.c | ||
| lmkd.c | ||
| lmkd.rc | ||
| OWNERS | ||
| README.md | ||
| statslog.c | ||
| statslog.h | ||
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