1 files changed, 31 insertions, 28 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ce39282d9c0d..892616bf2c77 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -194,6 +194,8 @@ __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
         update_load_add(&cfs_rq->load, se->load.weight);
         cfs_rq->nr_running++;
         se->on_rq = 1;
+
+        schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
 }
 
 static inline void
@@ -205,6 +207,8 @@ __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
         update_load_sub(&cfs_rq->load, se->load.weight);
         cfs_rq->nr_running--;
         se->on_rq = 0;
+
+        schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime);
 }
 
 static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
@@ -291,7 +295,7 @@ niced_granularity(struct sched_entity *curr, unsigned long granularity)
         /*
          * It will always fit into 'long':
          */
-        return (long) (tmp >> WMULT_SHIFT);
+        return (long) (tmp >> (WMULT_SHIFT-NICE_0_SHIFT));
 }
 
 static inline void
@@ -574,7 +578,6 @@ static void __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 
         prev_runtime = se->wait_runtime;
         __add_wait_runtime(cfs_rq, se, delta_fair);
-        schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
         delta_fair = se->wait_runtime - prev_runtime;
 
         /*
@@ -662,7 +665,6 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
                         if (tsk->state & TASK_UNINTERRUPTIBLE)
                                 se->block_start = rq_of(cfs_rq)->clock;
                 }
-                cfs_rq->wait_runtime -= se->wait_runtime;
 #endif
         }
         __dequeue_entity(cfs_rq, se);
@@ -671,22 +673,39 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
 /*
  * Preempt the current task with a newly woken task if needed:
  */
-static int
+static void
 __check_preempt_curr_fair(struct cfs_rq *cfs_rq, struct sched_entity *se,
                           struct sched_entity *curr, unsigned long granularity)
 {
         s64 __delta = curr->fair_key - se->fair_key;
+        unsigned long ideal_runtime, delta_exec;
+
+        /*
+         * ideal_runtime is compared against sum_exec_runtime, which is
+         * walltime, hence do not scale.
+         */
+        ideal_runtime = max(sysctl_sched_latency / cfs_rq->nr_running,
+                        (unsigned long)sysctl_sched_min_granularity);
+
+        /*
+         * If we executed more than what the latency constraint suggests,
+         * reduce the rescheduling granularity. This way the total latency
+         * of how much a task is not scheduled converges to
+         * sysctl_sched_latency:
+         */
+        delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
+        if (delta_exec > ideal_runtime)
+                granularity = 0;
 
         /*
          * Take scheduling granularity into account - do not
          * preempt the current task unless the best task has
          * a larger than sched_granularity fairness advantage:
+         *
+         * scale granularity as key space is in fair_clock.
          */
-        if (__delta > niced_granularity(curr, granularity)) {
+        if (__delta > niced_granularity(curr, granularity))
                 resched_task(rq_of(cfs_rq)->curr);
-                return 1;
-        }
-        return 0;
 }
 
 static inline void
@@ -702,6 +721,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
         update_stats_wait_end(cfs_rq, se);
         update_stats_curr_start(cfs_rq, se);
         set_cfs_rq_curr(cfs_rq, se);
+        se->prev_sum_exec_runtime = se->sum_exec_runtime;
 }
 
 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
@@ -731,7 +751,6 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
 
 static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 {
-        unsigned long gran, ideal_runtime, delta_exec;
         struct sched_entity *next;
 
         /*
@@ -748,22 +767,8 @@ static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
         if (next == curr)
                 return;
 
-        gran = sched_granularity(cfs_rq);
-        ideal_runtime = niced_granularity(curr,
-                max(sysctl_sched_latency / cfs_rq->nr_running,
-                    (unsigned long)sysctl_sched_min_granularity));
-        /*
-         * If we executed more than what the latency constraint suggests,
-         * reduce the rescheduling granularity. This way the total latency
-         * of how much a task is not scheduled converges to
-         * sysctl_sched_latency:
-         */
-        delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
-        if (delta_exec > ideal_runtime)
-                gran = 0;
-
-        if (__check_preempt_curr_fair(cfs_rq, next, curr, gran))
-                curr->prev_sum_exec_runtime = curr->sum_exec_runtime;
+        __check_preempt_curr_fair(cfs_rq, next, curr,
+                        sched_granularity(cfs_rq));
 }
 
 /**************************************************
@@ -1121,10 +1126,8 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
          * The statistical average of wait_runtime is about
          * -granularity/2, so initialize the task with that:
          */
-        if (sysctl_sched_features & SCHED_FEAT_START_DEBIT) {
+        if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)
                 se->wait_runtime = -(sched_granularity(cfs_rq) / 2);
-                schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
-        }
 
         __enqueue_entity(cfs_rq, se);
 }