[PATCH] sched: activate SCHED BATCH expired

To increase the strength of SCHED_BATCH as a scheduling hint we can
activate batch tasks on the expired array since by definition they are
latency insensitive tasks.

Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 8 insertions, 3 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index c4fd3fcd3feb..78c40dd2e19a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -484,6 +484,7 @@ struct signal_struct {
 #define MAX_PRIO                (MAX_RT_PRIO + 40)
 
 #define rt_task(p)              (unlikely((p)->prio < MAX_RT_PRIO))
+#define batch_task(p)           (unlikely((p)->policy == SCHED_BATCH))
 
 /*
  * Some day this will be a full-fledged user tracking system..
diff --git a/kernel/sched.c b/kernel/sched.c
index 73bb4d9ef989..dd153d6f8a04 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -667,9 +667,13 @@ static int effective_prio(task_t *p)
 /*
  * __activate_task - move a task to the runqueue.
  */
-static inline void __activate_task(task_t *p, runqueue_t *rq)
+static void __activate_task(task_t *p, runqueue_t *rq)
 {
-        enqueue_task(p, rq->active);
+        prio_array_t *target = rq->active;
+
+        if (batch_task(p))
+                target = rq->expired;
+        enqueue_task(p, target);
         rq->nr_running++;
 }
 
@@ -688,7 +692,7 @@ static int recalc_task_prio(task_t *p, unsigned long long now)
         unsigned long long __sleep_time = now - p->timestamp;
         unsigned long sleep_time;
 
-        if (unlikely(p->policy == SCHED_BATCH))
+        if (batch_task(p))
                 sleep_time = 0;
         else {
                 if (__sleep_time > NS_MAX_SLEEP_AVG)