sched: fix ideal_runtime calculations for reniced tasks

[deliverable/linux.git] / kernel / sched_fair.c

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ee3771850aaf1548e41bdcf224e95301d797a5e1..892616bf2c77ab212d28823c6fe1bc76b1cb7825 100644 (file)
--- 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
@@ -354,7 +358,7 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr)
        delta_fair = calc_delta_fair(delta_exec, lw);
        delta_mine = calc_delta_mine(delta_exec, curr->load.weight, lw);
 
-       if (cfs_rq->sleeper_bonus > sysctl_sched_latency) {
+       if (cfs_rq->sleeper_bonus > sysctl_sched_min_granularity) {
                delta = min((u64)delta_mine, cfs_rq->sleeper_bonus);
                delta = min(delta, (unsigned long)(
                        (long)sysctl_sched_runtime_limit - curr->wait_runtime));
@@ -489,6 +493,9 @@ update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
        unsigned long delta_fair;
 
+       if (unlikely(!se->wait_start_fair))
+               return;
+
        delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit),
                        (u64)(cfs_rq->fair_clock - se->wait_start_fair));
 
@@ -571,7 +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;
 
        /*
@@ -659,7 +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);
@@ -673,11 +678,31 @@ __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))
                resched_task(rq_of(cfs_rq)->curr);
@@ -696,6 +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)
@@ -1076,31 +1102,32 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr)
 static void task_new_fair(struct rq *rq, struct task_struct *p)
 {
        struct cfs_rq *cfs_rq = task_cfs_rq(p);
-       struct sched_entity *se = &p->se;
+       struct sched_entity *se = &p->se, *curr = cfs_rq_curr(cfs_rq);
 
        sched_info_queued(p);
 
+       update_curr(cfs_rq);
        update_stats_enqueue(cfs_rq, se);
        /*
         * Child runs first: we let it run before the parent
         * until it reschedules once. We set up the key so that
         * it will preempt the parent:
         */
-       p->se.fair_key = current->se.fair_key -
-               niced_granularity(&rq->curr->se, sched_granularity(cfs_rq)) - 1;
+       se->fair_key = curr->fair_key -
+               niced_granularity(curr, sched_granularity(cfs_rq)) - 1;
        /*
         * The first wait is dominated by the child-runs-first logic,
         * so do not credit it with that waiting time yet:
         */
        if (sysctl_sched_features & SCHED_FEAT_SKIP_INITIAL)
-               p->se.wait_start_fair = 0;
+               se->wait_start_fair = 0;
 
        /*
         * The statistical average of wait_runtime is about
         * -granularity/2, so initialize the task with that:
         */
        if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)
-               p->se.wait_runtime = -(sched_granularity(cfs_rq) / 2);
+               se->wait_runtime = -(sched_granularity(cfs_rq) / 2);
 
        __enqueue_entity(cfs_rq, se);
 }