[PATCH 11/22] sched: Delay task_contributes_to_load()

Peter Zijlstra
2011-03-02T17:47:55Z

[-- Attachment #1: sched-ttwu-contribute-to-load.patch --]
[-- Type: text/plain, Size: 1804 bytes --]

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.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
---
include/linux/sched.h | 1 +
kernel/sched.c | 16 ++++------------
2 files changed, 5 insertions(+), 12 deletions(-)

Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/include/linux/sched.h
@@ -1264,6 +1264,7 @@ 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;
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -2467,18 +2467,7 @@ static int try_to_wake_up(struct task_st
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) {
@@ -2503,6 +2492,9 @@ static int try_to_wake_up(struct task_st
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 */
activate_task(rq, p, en_flags);