Android Notes
Here are some miscellaneous notes on Android:
oom killer info
Google (Android) developer Arve Hjonevag added a lowmemorykiller feature to the staging area of the Linux kernel in January of 2009. This feature tries to reclaim memory before the system runs out (acting as a kind of cache manager, according to Arve). In Linus' 2.6.28-rc tree this appears in
Application lifecycle (and activity states) can be found here: http://code.google.com/android/intro/lifecycle.html
Applications in different stages of their lifecycle receive a different oom_adj value, which affects the probability of their being reaped.
Initial lowmemorykiller thresholds are set by /etc/init.rc (with the following lines): {{{
- Define the oom_adj values for the classes of processes that can be
- killed by the kernel. These are used in ActivityManagerService.
setprop ro.FOREGROUND_APP_ADJ 0 setprop ro.VISIBLE_APP_ADJ 1 setprop ro.SECONDARY_SERVER_ADJ 2 setprop ro.HIDDEN_APP_MIN_ADJ 7 setprop ro.CONTENT_PROVIDER_ADJ 14 setprop ro.EMPTY_APP_ADJ 15
- Define the memory thresholds at which the above process classes will
- be killed. These numbers are in pages (4k).
setprop ro.FOREGROUND_APP_MEM 1536 setprop ro.VISIBLE_APP_MEM 2048 setprop ro.SECONDARY_SERVER_MEM 4096 setprop ro.HIDDEN_APP_MEM 5120 setprop ro.CONTENT_PROVIDER_MEM 5632 setprop ro.EMPTY_APP_MEM 6144
- Write value must be consistent with the above properties.
write /sys/module/lowmemorykiller/parameters/adj 0,1,2,7,14,15
write /proc/sys/vm/overcommit_memory 1 write /sys/module/lowmemorykiller/parameters/minfree 1536,2048,4096,5120,5632,6144
class_start default
# Set init its forked children's oom_adj. write /proc/1/oom_adj -16
}}}