platform_system_core/logcat/logcatd.rc

on property:persist.logd.logpersistd=logcatd
    # all exec/services are called with umask(077), so no gain beyond 0700
    mkdir /data/misc/logd 0700 logd log
    # logd for write to /data/misc/logd, log group for read from pstore (-L)
    exec - logd log -- /system/bin/logcat -L -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 1024 -n 256
    start logcatd

service logcatd /system/bin/logcat -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 1024 -n 256
    class late_start
    disabled
    # logd for write to /data/misc/logd, log group for read from log daemon
    user logd
    group log
    writepid /dev/cpuset/system-background/tasks