[GIT PULL] scheduler fixes

Ingo Molnar
2016-07-08T13:54:00Z

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

# HEAD: ea1dc6fc6242f991656e35e2ed3d90ec1cd13418 sched/fair: Fix calc_cfs_shares() fixed point arithmetics width confusion

Two load-balancing fixes for cgroups-intense workloads.

Thanks,

Ingo

------------------>
Peter Zijlstra (2):
sched/fair: Fix effective_load() to consistently use smoothed load
sched/fair: Fix calc_cfs_shares() fixed point arithmetics width confusion

kernel/sched/fair.c | 42 ++++++++++++++++++++----------------------
1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bdcbeea90c95..c8c5d2d48424 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -735,8 +735,6 @@ void post_init_entity_util_avg(struct sched_entity *se)
}
}

-static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq);
-static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq);
#else
void init_entity_runnable_average(struct sched_entity *se)
{
@@ -2499,28 +2497,22 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)

#ifdef CONFIG_FAIR_GROUP_SCHED
# ifdef CONFIG_SMP
-static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
+static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
{
- long tg_weight;
+ long tg_weight, load, shares;

/*
- * Use this CPU's real-time load instead of the last load contribution
- * as the updating of the contribution is delayed, and we will use the
- * the real-time load to calc the share. See update_tg_load_avg().
+ * This really should be: cfs_rq->avg.load_avg, but instead we use
+ * cfs_rq->load.weight, which is its upper bound. This helps ramp up
+ * the shares for small weight interactive tasks.
*/
- tg_weight = atomic_long_read(&tg->load_avg);
- tg_weight -= cfs_rq->tg_load_avg_contrib;
- tg_weight += cfs_rq->load.weight;
+ load = scale_load_down(cfs_rq->load.weight);

- return tg_weight;
-}
-
-static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
-{
- long tg_weight, load, shares;
+ tg_weight = atomic_long_read(&tg->load_avg);

- tg_weight = calc_tg_weight(tg, cfs_rq);
- load = cfs_rq->load.weight;
+ /* Ensure tg_weight >= load */
+ tg_weight -= cfs_rq->tg_load_avg_contrib;
+ tg_weight += load;

shares = (tg->shares * load);
if (tg_weight)
@@ -2539,6 +2531,7 @@ static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
return tg->shares;
}
# endif /* CONFIG_SMP */
+
static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
unsigned long weight)
{
@@ -4946,19 +4939,24 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
return wl;

for_each_sched_entity(se) {
- long w, W;
+ struct cfs_rq *cfs_rq = se->my_q;
+ long W, w = cfs_rq_load_avg(cfs_rq);

- tg = se->my_q->tg;
+ tg = cfs_rq->tg;

/*
* W = @wg + \Sum rw_j
*/
- W = wg + calc_tg_weight(tg, se->my_q);
+ W = wg + atomic_long_read(&tg->load_avg);
+
+ /* Ensure \Sum rw_j >= rw_i */
+ W -= cfs_rq->tg_load_avg_contrib;
+ W += w;

/*
* w = rw_i + @wl
*/
- w = cfs_rq_load_avg(se->my_q) + wl;
+ w += wl;

/*
* wl = S * s'_i; see (2)