sched: group scheduler, fix bloat

Recent fix to check_preempt_wakeup() to check for preemption at higher
levels caused a size bloat for !CONFIG_FAIR_GROUP_SCHED.

Fix the problem.

  42277   10598     320   53195    cfcb kernel/sched.o-before_this_patch
  42216   10598     320   53134    cf8e kernel/sched.o-after_this_patch

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 25 insertions, 18 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c44a295eee0e..57e7f3672fd7 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -652,15 +652,21 @@ static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
         list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
 
-/* Do the two (enqueued) tasks belong to the same group ? */
-static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
+/* Do the two (enqueued) entities belong to the same group ? */
+static inline int
+is_same_group(struct sched_entity *se, struct sched_entity *pse)
 {
-        if (curr->se.cfs_rq == p->se.cfs_rq)
+        if (se->cfs_rq == pse->cfs_rq)
                 return 1;
 
         return 0;
 }
 
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+        return se->parent;
+}
+
 #else   /* CONFIG_FAIR_GROUP_SCHED */
 
 #define for_each_sched_entity(se) \
@@ -693,11 +699,17 @@ static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
                 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
 
-static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
+static inline int
+is_same_group(struct sched_entity *se, struct sched_entity *pse)
 {
         return 1;
 }
 
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+        return NULL;
+}
+
 #endif  /* CONFIG_FAIR_GROUP_SCHED */
 
 /*
@@ -787,8 +799,9 @@ static void yield_task_fair(struct rq *rq)
 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
 {
         struct task_struct *curr = rq->curr;
-        struct cfs_rq *cfs_rq = task_cfs_rq(curr), *pcfs_rq;
+        struct cfs_rq *cfs_rq = task_cfs_rq(curr);
         struct sched_entity *se = &curr->se, *pse = &p->se;
+        s64 delta;
 
         if (unlikely(rt_prio(p->prio))) {
                 update_rq_clock(rq);
@@ -797,21 +810,15 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
                 return;
         }
 
-        for_each_sched_entity(se) {
-                cfs_rq = cfs_rq_of(se);
-                pcfs_rq = cfs_rq_of(pse);
+        while (!is_same_group(se, pse)) {
+                se = parent_entity(se);
+                pse = parent_entity(pse);
+        }
 
-                if (cfs_rq == pcfs_rq) {
-                        s64 delta = se->vruntime - pse->vruntime;
+        delta = se->vruntime - pse->vruntime;
 
-                        if (delta > (s64)sysctl_sched_wakeup_granularity)
-                                resched_task(curr);
-                        break;
-                }
-#ifdef CONFIG_FAIR_GROUP_SCHED
-                pse = pse->parent;
-#endif
-        }
+        if (delta > (s64)sysctl_sched_wakeup_granularity)
+                resched_task(curr);
 }
 
 static struct task_struct *pick_next_task_fair(struct rq *rq)