[Samsung Galaxy Nexus] helloworld1:
The error is quite excessive and polluting the logcat. Excessive logs could cause lag in theory.

I also PSed some of the pid there. They are not just launcher. There are a few aosp processes and a few third party processes too.

W/System.err( 1180): java.lang.SecurityException: No permission to set to given group
W/System.err( 1180): at android.os.Process.setProcessGroup(Native Method)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.updateOomAdjLocked(ActivityManagerService.java:13527)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.updateOomAdjLocked(ActivityManagerService.java:13568)
W/System.err( 1180): at com.android.server.am.ActiveServices.serviceDoneExecutingLocked(ActiveServices.java:1449)
W/System.err( 1180): at com.android.server.am.ActiveServices.serviceDoneExecutingLocked(ActiveServices.java:1420)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.serviceDoneExecuting(ActivityManagerService.java:11121)
W/System.err( 1180): at android.app.ActivityManagerNative.onTransact(ActivityManagerNative.java:826)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.onTransact(ActivityManagerService.java:1674)
W/System.err( 1180): at android.os.Binder.execTransact(Binder.java:351)
W/System.err( 1180): at com.android.server.SystemServer.init1(Native Method)
W/System.err( 1180): at com.android.server.SystemServer.main(SystemServer.java:1064)
W/System.err( 1180): at java.lang.reflect.Method.invokeNative(Native Method)
W/System.err( 1180): at java.lang.reflect.Method.invoke(Method.java:511)
W/System.err( 1180): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
W/System.err( 1180): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
W/System.err( 1180): at dalvik.system.NativeStart.main(Native Method)
W/SchedPolicy( 1180): add_tid_to_cgroup failed to write '5949' (Permission denied); policy=0
W/ActivityManager( 1180): Failed setting process group of 5949 to 0

W/SchedPolicy( 1180): add_tid_to_cgroup failed to write '2016' (Permission denied); policy=1
W/ActivityManager( 1180): Failed setting process group of 2016 to -1
W/System.err( 1180): java.lang.SecurityException: No permission to set to given group
W/System.err( 1180): at android.os.Process.setProcessGroup(Native Method)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.updateOomAdjLocked(ActivityManagerService.java:13527)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.updateOomAdjLocked(ActivityManagerService.java:13647)
W/System.err( 1180): at com.android.server.am.BroadcastQueue.processNextBroadcast(BroadcastQueue.java:534)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.finishReceiver(ActivityManagerService.java:12082)
W/System.err( 1180): at android.app.ActivityManagerNative.onTransact(ActivityManagerNative.java:375)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.onTransact(ActivityManagerService.java:1674)
W/System.err( 1180): at android.os.Binder.execTransact(Binder.java:351)
W/System.err( 1180): at dalvik.system.NativeStart.run(Native Method)

W/System.err( 1180): java.lang.SecurityException: No permission to set to given group
W/ActivityManager( 1180): Failed setting process group of 4957 to -1
W/System.err( 1180): at android.os.Process.setProcessGroup(Native Method)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.updateOomAdjLocked(ActivityManagerService.java:13527)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.updateOomAdjLocked(ActivityManagerService.java:13647)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.updateLruProcessLocked(ActivityManagerService.java:1902)
W/System.err( 1180): at com.android.server.am.ActiveServices.realStartServiceLocked(ActiveServices.java:1089)
W/System.err( 1180): at com.android.server.am.ActiveServices.bringUpServiceLocked(ActiveServices.java:1022)
W/System.err( 1180): at com.android.server.am.ActiveServices.bindServiceLocked(ActiveServices.java:522)
W/System.err( 1180): at com.android.server.am.ActivityManagerService.bindService(ActivityManagerService.java:11080)
W/System.err( 1180): at android.app.ContextImpl.bindService(ContextImpl.java:1431)
W/System.err( 1180): at com.android.server.dreams.DreamController.startDream(DreamController.java:119)
W/System.err( 1180): at com.android.server.dreams.DreamManagerService$3.run(DreamManagerService.java:339)
W/System.err( 1180): at android.os.Handler.handleCallback(Handler.java:725)
W/System.err( 1180): at android.os.Handler.dispatchMessage(Handler.java:92)
W/System.err( 1180): at android.os.Looper.loop(Looper.java:137)
W/System.err( 1180): at android.os.HandlerThread.run(HandlerThread.java:60)

[liberty@liberty-host test]% adb shell
shell@android:/ $ ps |grep 4957
u0_a13 4957 127 492516 54696 ffffffff 00000000 S com.google.android.deskclock
shell@android:/ $ ps |grep 5949
u0_a14 5949 127 470544 26124 ffffffff 00000000 S android.process.media
shell@android:/ $ ps |grep 2016
u0_a86 2016 127 473024 21960 ffffffff 00000000 S com.kebab.Llama
shell@android:/ $ ps |grep 4545
u0_a55 4545 127 487444 33932 ffffffff 00000000 S com.google.android.googlequicksearchbox
ps |grep 1598
u0_a31 1598 127 518204 72916 ffffffff 00000000 S com.android.launcher

% adb logcat | grep 'Failed setting process group' | awk '{ print $8 }' > /tmp/a
% for i in `cat /tmp/a`; do adb shell ps | grep $i; done|sort |uniq
u0_a0 3077 127 485392 26452 ffffffff 00000000 S android.process.acore
u0_a126 1548 127 503988 39556 ffffffff 00000000 S com.nuance.swype.dtc
u0_a13 4957 127 482304 44432 ffffffff 00000000 S com.google.android.deskclock
u0_a13 4957 127 482304 44440 ffffffff 00000000 S com.google.android.deskclock
u0_a14 5949 127 470544 26108 ffffffff 00000000 S android.process.media
u0_a31 1598 127 515024 72748 ffffffff 00000000 S com.android.launcher
u0_a35 1623 127 476832 22424 ffffffff 00000000 S com.google.android.apps.maps:MapsBackgroundService
u0_a35 29724 127 487256 23780 ffffffff 00000000 S com.google.android.apps.maps:GoogleLocationService
u0_a38 5220 127 493616 31592 ffffffff 00000000 S com.google.android.music:main
u0_a55 4545 127 487444 31328 ffffffff 00000000 S com.google.android.googlequicksearchbox
u0_a55 4545 127 488484 31336 ffffffff 00000000 S com.google.android.googlequicksearchbox
u0_a6 5755 127 478036 24368 ffffffff 00000000 S com.google.android.calendar
u0_a62 6045 127 496060 30572 ffffffff 00000000 S com.google.android.youtube
u0_a66 3374 127 467620 25860 ffffffff 00000000 S com.painless.pc
u0_a7 5740 127 467780 24040 ffffffff 00000000 S com.android.providers.calendar
u0_a81 5345 127 526976 64752 ffffffff 00000000 S com.nitrodesk.honey.nitroid
u0_a86 2016 127 473024 22068 ffffffff 00000000 S com.kebab.Llama
u0_a9 1673 127 510888 29148 ffffffff 00000000 S com.google.process.location
u0_a9 1673 127 511092 29116 ffffffff 00000000 S com.google.process.location
u0_a9 1673 127 512132 29152 ffffffff 00000000 S com.google.process.location
u0_a9 1673 127 512132 29156 ffffffff 00000000 S com.google.process.location
u0_a9 1673 127 512132 29160 ffffffff 00000000 S com.google.process.location
u0_a9 1718 127 691348 30752 ffffffff 00000000 S com.google.process.gapps
u0_a9 6166 127 481668 27268 ffffffff 00000000 S com.google.android.gsf.login

I am running stock ROM. The init.rc should have the correct configuration:

# Create cgroup mount points for process groups
mkdir /dev/cpuctl
mount cgroup none /dev/cpuctl cpu,timer_slack
chown system system /dev/cpuctl
chown system system /dev/cpuctl/tasks
chmod 0660 /dev/cpuctl/tasks
write /dev/cpuctl/cpu.shares 1024
write /dev/cpuctl/cpu.rt_runtime_us 950000
write /dev/cpuctl/cpu.rt_period_us 1000000