From: Con Kolivas <kernel@kolivas.org>

Add an above_background_load() function which can be used by other
subsystems to detect if there is anything besides niced tasks running. 
Place it in sched.h to allow it to be compiled out if not used.

Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 include/linux/sched.h |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Index: linux-2.6.20-ck1/include/linux/sched.h
===================================================================
--- linux-2.6.20-ck1.orig/include/linux/sched.h	2007-02-16 19:01:31.000000000 +1100
+++ linux-2.6.20-ck1/include/linux/sched.h	2007-02-16 19:01:33.000000000 +1100
@@ -753,6 +753,22 @@ extern unsigned int max_cache_size;
 
 #endif	/* CONFIG_SMP */
 
+/*
+ * A runqueue laden with a single nice 0 task scores a weighted_cpuload of
+ * SCHED_LOAD_SCALE. This function returns 1 if any cpu is laden with a
+ * task of nice 0 or enough lower priority tasks to bring up the
+ * weighted_cpuload
+ */
+static inline int above_background_load(void)
+{
+	unsigned long cpu;
+
+	for_each_online_cpu(cpu) {
+		if (weighted_cpuload(cpu) >= SCHED_LOAD_SCALE)
+			return 1;
+	}
+	return 0;
+}
 
 struct io_context;			/* See blkdev.h */
 struct cpuset;