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authorCon Kolivas <kernel@kolivas.org>2007-07-26 13:40:43 +0200
committerIngo Molnar <mingo@elte.hu>2007-07-26 13:40:43 +0200
commitd02c7a8cf208eb80a3ccbff40a6bebe8902af35a (patch)
treeb6e2a0393bf917e5e04be955d6c6d5384caa4dfa /include/linux
parentb762f3ffb797c1281a38a1c82194534055fba5ec (diff)
[PATCH] sched: add above_background_load() function
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. Unused for now, but it is a useful hint to the IO scheduler and to swap-prefetch. Signed-off-by: Con Kolivas <kernel@kolivas.org> Cc: Peter Williams <pwil3058@bigpond.net.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/sched.h16
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7a4de876874..2e490271acf 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -786,6 +786,22 @@ extern int partition_sched_domains(cpumask_t *partition1,
#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;