BACKPORT: sched/fair: Factorize PELT update

Every time we modify load/utilization of sched_entity, we start to
sync it with its cfs_rq. This update is done in different ways:

 - when attaching/detaching a sched_entity, we update cfs_rq and then
   we sync the entity with the cfs_rq.

 - when enqueueing/dequeuing the sched_entity, we update both
   sched_entity and cfs_rq metrics to now.

Use update_load_avg() everytime we have to update and sync cfs_rq and
sched_entity before changing the state of a sched_enity.

Change-Id: Ibde9a7e07ac80e9d5753bb4a0c30dfb3643cc666
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[backported FROMLIST]
Signed-off-by: Andres Oportus <andresoportus@google.com>
(cherry picked from commit d31b1a66cbe0931733583ad9d9e8c6cfd710907d)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 58b84c8d707121828670e5fbfe6be1e94c15715a..411f7749e73db73be583915699600c8be90622e9 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2916,8 +2916,14 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq)
        return decayed || removed;
 }
 
+/*
+ * Optional action to be done while updating the load average
+ */
+#define UPDATE_TG      0x1
+#define SKIP_AGE_LOAD  0x2
+
 /* Update task and its cfs_rq load average */
-static inline void update_load_avg(struct sched_entity *se, int update_tg)
+static inline void update_load_avg(struct sched_entity *se, int flags)
 {
        struct cfs_rq *cfs_rq = cfs_rq_of(se);
        u64 now = cfs_rq_clock_task(cfs_rq);
@@ -2927,11 +2933,13 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg)
         * Track task load average for carrying it to new CPU after migrated, and
         * track group sched_entity load average for task_h_load calc in migration
         */
-       __update_load_avg(now, cpu, &se->avg,
+       if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD)) {
+               __update_load_avg(now, cpu, &se->avg,
                          se->on_rq * scale_load_down(se->load.weight),
                          cfs_rq->curr == se, NULL);
+       }
 
-       if (update_cfs_rq_load_avg(now, cfs_rq, true) && update_tg)
+       if (update_cfs_rq_load_avg(now, cfs_rq, true) && (flags & UPDATE_TG))
                update_tg_load_avg(cfs_rq, 0);
 
        if (entity_is_task(se))
@@ -2948,24 +2956,6 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg)
  */
 static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-       if (!sched_feat(ATTACH_AGE_LOAD))
-               goto skip_aging;
-
-       /*
-        * If we got migrated (either between CPUs or between cgroups) we'll
-        * have aged the average right before clearing @last_update_time.
-        */
-       if (se->avg.last_update_time) {
-               __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
-                                 &se->avg, 0, 0, NULL);
-
-               /*
-                * XXX: we could have just aged the entire load away if we've been
-                * absent from the fair class for too long.
-                */
-       }
-
-skip_aging:
        se->avg.last_update_time = cfs_rq->avg.last_update_time;
        cfs_rq->avg.load_avg += se->avg.load_avg;
        cfs_rq->avg.load_sum += se->avg.load_sum;
@@ -2985,9 +2975,6 @@ skip_aging:
  */
 static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-       __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
-                         &se->avg, se->on_rq * scale_load_down(se->load.weight),
-                         cfs_rq->curr == se, NULL);
 
        sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
        sub_positive(&cfs_rq->avg.load_sum, se->avg.load_sum);
@@ -3002,34 +2989,20 @@ static inline void
 enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
        struct sched_avg *sa = &se->avg;
-       u64 now = cfs_rq_clock_task(cfs_rq);
-       int migrated, decayed;
-
-       migrated = !sa->last_update_time;
-       if (!migrated) {
-               __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,
-                       se->on_rq * scale_load_down(se->load.weight),
-                       cfs_rq->curr == se, NULL);
-       }
-
-       decayed = update_cfs_rq_load_avg(now, cfs_rq, !migrated);
 
        cfs_rq->runnable_load_avg += sa->load_avg;
        cfs_rq->runnable_load_sum += sa->load_sum;
 
-       if (migrated)
+       if (!sa->last_update_time) {
                attach_entity_load_avg(cfs_rq, se);
-
-       if (decayed || migrated)
                update_tg_load_avg(cfs_rq, 0);
+       }
 }
 
 /* Remove the runnable load generated by se from cfs_rq's runnable load average */
 static inline void
 dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-       update_load_avg(se, 1);
-
        cfs_rq->runnable_load_avg =
                max_t(long, cfs_rq->runnable_load_avg - se->avg.load_avg, 0);
        cfs_rq->runnable_load_sum =
@@ -3122,11 +3095,16 @@ static int idle_balance(struct rq *this_rq);
 
 #else /* CONFIG_SMP */
 
-static inline void update_load_avg(struct sched_entity *se, int update_tg)
+static inline int
+update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq)
 {
-       cpufreq_update_util(rq_of(cfs_rq_of(se)), 0);
+       return 0;
 }
 
+#define UPDATE_TG      0x0
+#define SKIP_AGE_LOAD  0x0
+
+static inline void update_load_avg(struct sched_entity *se, int not_used1){}
 static inline void
 enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
 static inline void
@@ -3269,6 +3247,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
         * Update run-time statistics of the 'current'.
         */
        update_curr(cfs_rq);
+       update_load_avg(se, UPDATE_TG);
        enqueue_entity_load_avg(cfs_rq, se);
        account_entity_enqueue(cfs_rq, se);
        update_cfs_shares(cfs_rq);
@@ -3344,6 +3323,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
         * Update run-time statistics of the 'current'.
         */
        update_curr(cfs_rq);
+       update_load_avg(se, UPDATE_TG);
        dequeue_entity_load_avg(cfs_rq, se);
 
        update_stats_dequeue(cfs_rq, se);
@@ -3434,7 +3414,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
                 */
                update_stats_wait_end(cfs_rq, se);
                __dequeue_entity(cfs_rq, se);
-               update_load_avg(se, 1);
+               update_load_avg(se, UPDATE_TG);
        }
 
        update_stats_curr_start(cfs_rq, se);
@@ -3550,7 +3530,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
        /*
         * Ensure that runnable average is periodically updated.
         */
-       update_load_avg(curr, 1);
+       update_load_avg(curr, UPDATE_TG);
        update_cfs_shares(cfs_rq);
 
 #ifdef CONFIG_SCHED_HRTICK
@@ -4479,7 +4459,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
                if (cfs_rq_throttled(cfs_rq))
                        break;
 
-               update_load_avg(se, 1);
+               update_load_avg(se, UPDATE_TG);
                update_cfs_shares(cfs_rq);
        }
 
@@ -4581,7 +4561,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
                if (cfs_rq_throttled(cfs_rq))
                        break;
 
-               update_load_avg(se, 1);
+               update_load_avg(se, UPDATE_TG);
                update_cfs_shares(cfs_rq);
        }
 
@@ -9391,10 +9371,9 @@ static inline bool vruntime_normalized(struct task_struct *p)
 static void detach_entity_cfs_rq(struct sched_entity *se)
 {
        struct cfs_rq *cfs_rq = cfs_rq_of(se);
-       u64 now = cfs_rq_clock_task(cfs_rq);
 
        /* Catch up with the cfs_rq and remove our load when we leave */
-       update_cfs_rq_load_avg(now, cfs_rq, false);
+       update_load_avg(se, 0);
        detach_entity_load_avg(cfs_rq, se);
        update_tg_load_avg(cfs_rq, false);
 }
@@ -9402,7 +9381,6 @@ static void detach_entity_cfs_rq(struct sched_entity *se)
 static void attach_entity_cfs_rq(struct sched_entity *se)
 {
        struct cfs_rq *cfs_rq = cfs_rq_of(se);
-       u64 now = cfs_rq_clock_task(cfs_rq);
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
        /*
@@ -9413,7 +9391,7 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
 #endif
 
        /* Synchronize entity with its cfs_rq */
-       update_cfs_rq_load_avg(now, cfs_rq, false);
+       update_load_avg(se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
        attach_entity_load_avg(cfs_rq, se);
        update_tg_load_avg(cfs_rq, false);
 }