add system-background cpuset

add a new cpuset for system services that should not run on
larger cores

bug 24144797

Change-Id: I21a54f0d6b46b3b8bd8c4564b8685c88cfc4a57d

rootdir/init.rc

@@ -143,14 +143,20 @@ on init
     mkdir /dev/cpuset/foreground
     mkdir /dev/cpuset/foreground/boost
     mkdir /dev/cpuset/background
+    # system-background is for system tasks that should only run on
+    # little cores, not on bigs
+    # to be used only by init, so don't change the permissions
+    mkdir /dev/cpuset/system-background
     # this ensures that the cpusets are present and usable, but the device's
     # init.rc must actually set the correct cpus
     write /dev/cpuset/foreground/cpus 0
     write /dev/cpuset/foreground/boost/cpus 0
     write /dev/cpuset/background/cpus 0
+    write /dev/cpuset/system-background/cpus 0
     write /dev/cpuset/foreground/mems 0
     write /dev/cpuset/foreground/boost/mems 0
     write /dev/cpuset/background/mems 0
+    write /dev/cpuset/system-background/mems 0
     chown system system /dev/cpuset
     chown system system /dev/cpuset/foreground
     chown system system /dev/cpuset/foreground/boost
@@ -548,9 +554,11 @@ service logd /system/bin/logd
     socket logdr seqpacket 0666 logd logd
     socket logdw dgram 0222 logd logd
     group root system
+     writepid /dev/cpuset/system-background/tasks
 
 service logd-reinit /system/bin/logd --reinit
     oneshot
+    writepid /dev/cpuset/system-background/tasks
     disabled
 
 service healthd /sbin/healthd
@@ -585,6 +593,7 @@ service lmkd /system/bin/lmkd
     class core
     critical
     socket lmkd seqpacket 0660 system system
+    writepid /dev/cpuset/system-background/tasks
 
 service servicemanager /system/bin/servicemanager
     class core
@@ -614,9 +623,11 @@ service netd /system/bin/netd
 
 service debuggerd /system/bin/debuggerd
     class main
+    writepid /dev/cpuset/system-background/tasks
 
 service debuggerd64 /system/bin/debuggerd64
     class main
+    writepid /dev/cpuset/system-background/tasks
 
 service ril-daemon /system/bin/rild
     class main
@@ -631,6 +642,7 @@ service surfaceflinger /system/bin/surfaceflinger
     user system
     group graphics drmrpc
     onrestart restart zygote
+    writepid /dev/cpuset/system-background/tasks
 
 service drm /system/bin/drmserver
     class main
@@ -725,6 +737,7 @@ service perfprofd /system/xbin/perfprofd
     class late_start
     user root
     oneshot
+    writepid /dev/cpuset/system-background/tasks
 
 on property:persist.logd.logpersistd=logcatd
     # all exec/services are called with umask(077), so no gain beyond 0700
@@ -739,3 +752,4 @@ service logcatd /system/bin/logcat -b all -v threadtime -v usec -v printable -D
     # logd for write to /data/misc/logd, log group for read from log daemon
     user logd
     group log
+    writepid /dev/cpuset/system-background/tasks