--- sys/kern/kern_clock.c.orig	2016-01-29 15:18:38.057157685 +0100
+++ sys/kern/kern_clock.c	2016-04-01 18:52:35.239191642 +0200
@@ -696,10 +696,14 @@
 {
 
 	statclock_cnt(1, usermode);
 }
 
+static int cp_time_mode = 0;
+SYSCTL_INT(_kern, OID_AUTO, cp_time_mode, CTLFLAG_RW, &cp_time_mode, 0,
+    "Charge idle threads as: 0=user (default), 1=nice (server), 2=idle (desktop/mobile)");
+
 void
 statclock_cnt(int cnt, int usermode)
 {
 	struct rusage *ru;
 	struct vmspace *vm;
@@ -715,11 +719,14 @@
 	if (usermode) {
 		/*
 		 * Charge the time as appropriate.
 		 */
 		td->td_uticks += cnt;
-		if (p->p_nice > NZERO)
+		if (cp_time_mode == 2 && td->td_pri_class == PRI_IDLE)
+			cp_time[CP_IDLE] += cnt;
+		else if (p->p_nice > NZERO ||
+		   (cp_time_mode == 1 && td->td_pri_class == PRI_IDLE))
 			cp_time[CP_NICE] += cnt;
 		else
 			cp_time[CP_USER] += cnt;
 	} else {
 		/*