sched: Don't call task_group() too many times in set_task_rq()

It improves perfomance, especially if autogroup is enabled.

The size of set_task_rq() was 0x180 and now it is 0xa0.

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Acked-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1321020240-3874331-1-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -793,14 +793,18 @@ static inline struct task_group *task_group(struct task_struct *p)
 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 {
+#if defined(CONFIG_FAIR_GROUP_SCHED) || defined(CONFIG_RT_GROUP_SCHED)
+	struct task_group *tg = task_group(p);
+#endif
+
 #ifdef CONFIG_FAIR_GROUP_SCHED
-	p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
-	p->se.parent = task_group(p)->se[cpu];
+	p->se.cfs_rq = tg->cfs_rq[cpu];
+	p->se.parent = tg->se[cpu];
 #endif
 
 #ifdef CONFIG_RT_GROUP_SCHED
-	p->rt.rt_rq  = task_group(p)->rt_rq[cpu];
-	p->rt.parent = task_group(p)->rt_se[cpu];
+	p->rt.rt_rq  = tg->rt_rq[cpu];
+	p->rt.parent = tg->rt_se[cpu];
 #endif
 }