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

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7f5732f8c618583f1769ed4fee447dcef925cbce..25c50317ddc1151f9cde194dcbb9897f9534f174 100644 (file)
--- 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 7a5eb2620785aa12d72380ce89847d15eb86edff..fd32b78c123ca50ffd54f01258819487909921a6 100644 (file)
--- 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);