sched: Delay task_contributes_to_load()

In prepratation of having to call task_contributes_to_load() without
holding rq->lock, we need to store the result until we do and can
update the rq accounting accordingly.

Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110405152729.151523907@chello.nl

2 files changed, 5 insertions, 12 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7f5732f8c618..25c50317ddc1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1273,6 +1273,7 @@ struct task_struct {
 
         /* Revert to default priority/policy when forking */
         unsigned sched_reset_on_fork:1;
+        unsigned sched_contributes_to_load:1;
 
         pid_t pid;
         pid_t tgid;
diff --git a/kernel/sched.c b/kernel/sched.c
index 7a5eb2620785..fd32b78c123c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2519,18 +2519,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
         if (unlikely(task_running(rq, p)))
                 goto out_activate;
 
-        /*
-         * In order to handle concurrent wakeups and release the rq->lock
-         * we put the task in TASK_WAKING state.
-         *
-         * First fix up the nr_uninterruptible count:
-         */
-        if (task_contributes_to_load(p)) {
-                if (likely(cpu_online(orig_cpu)))
-                        rq->nr_uninterruptible--;
-                else
-                        this_rq()->nr_uninterruptible--;
-        }
+        p->sched_contributes_to_load = !!task_contributes_to_load(p);
         p->state = TASK_WAKING;
 
         if (p->sched_class->task_waking) {
@@ -2555,6 +2544,9 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
         WARN_ON(task_cpu(p) != cpu);
         WARN_ON(p->state != TASK_WAKING);
 
+        if (p->sched_contributes_to_load)
+                rq->nr_uninterruptible--;
+
 out_activate:
 #endif /* CONFIG_SMP */
         ttwu_activate(rq, p, en_flags);