1 files changed, 26 insertions, 25 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index d906f72b42d2..945a97b9600d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -819,6 +819,13 @@ const_debug unsigned int sysctl_sched_nr_migrate = 32;
 unsigned int sysctl_sched_shares_ratelimit = 250000;
 
 /*
+ * Inject some fuzzyness into changing the per-cpu group shares
+ * this avoids remote rq-locks at the expense of fairness.
+ * default: 4
+ */
+unsigned int sysctl_sched_shares_thresh = 4;
+
+/*
  * period over which we measure -rt task cpu usage in us.
  * default: 1s
  */
@@ -1454,8 +1461,8 @@ static void __set_se_shares(struct sched_entity *se, unsigned long shares);
  * Calculate and set the cpu's group shares.
  */
 static void
-__update_group_shares_cpu(struct task_group *tg, int cpu,
-                          unsigned long sd_shares, unsigned long sd_rq_weight)
+update_group_shares_cpu(struct task_group *tg, int cpu,
+                        unsigned long sd_shares, unsigned long sd_rq_weight)
 {
         int boost = 0;
         unsigned long shares;
@@ -1486,19 +1493,23 @@ __update_group_shares_cpu(struct task_group *tg, int cpu,
          *
          */
         shares = (sd_shares * rq_weight) / (sd_rq_weight + 1);
+        shares = clamp_t(unsigned long, shares, MIN_SHARES, MAX_SHARES);
 
-        /*
-         * record the actual number of shares, not the boosted amount.
-         */
-        tg->cfs_rq[cpu]->shares = boost ? 0 : shares;
-        tg->cfs_rq[cpu]->rq_weight = rq_weight;
+        if (abs(shares - tg->se[cpu]->load.weight) >
+                        sysctl_sched_shares_thresh) {
+                struct rq *rq = cpu_rq(cpu);
+                unsigned long flags;
 
-        if (shares < MIN_SHARES)
-                shares = MIN_SHARES;
-        else if (shares > MAX_SHARES)
-                shares = MAX_SHARES;
+                spin_lock_irqsave(&rq->lock, flags);
+                /*
+                 * record the actual number of shares, not the boosted amount.
+                 */
+                tg->cfs_rq[cpu]->shares = boost ? 0 : shares;
+                tg->cfs_rq[cpu]->rq_weight = rq_weight;
 
-        __set_se_shares(tg->se[cpu], shares);
+                __set_se_shares(tg->se[cpu], shares);
+                spin_unlock_irqrestore(&rq->lock, flags);
+        }
 }
 
 /*
@@ -1527,14 +1538,8 @@ static int tg_shares_up(struct task_group *tg, void *data)
         if (!rq_weight)
                 rq_weight = cpus_weight(sd->span) * NICE_0_LOAD;
 
-        for_each_cpu_mask(i, sd->span) {
-                struct rq *rq = cpu_rq(i);
-                unsigned long flags;
-
-                spin_lock_irqsave(&rq->lock, flags);
-                __update_group_shares_cpu(tg, i, shares, rq_weight);
-                spin_unlock_irqrestore(&rq->lock, flags);
-        }
+        for_each_cpu_mask(i, sd->span)
+                update_group_shares_cpu(tg, i, shares, rq_weight);
 
         return 0;
 }
@@ -4443,12 +4448,8 @@ need_resched_nonpreemptible:
         if (sched_feat(HRTICK))
                 hrtick_clear(rq);
 
-        /*
-         * Do the rq-clock update outside the rq lock:
-         */
-        local_irq_disable();
+        spin_lock_irq(&rq->lock);
         update_rq_clock(rq);
-        spin_lock(&rq->lock);
         clear_tsk_need_resched(prev);
 
         if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {