sched/fair: Take into account runnable_avg to classify group

Take into account the new runnable_avg signal to classify a group and to
mitigate the volatility of util_avg in face of intensive migration or
new task with random utilization.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: "Dietmar Eggemann <dietmar.eggemann@arm.com>"
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Link: https://lore.kernel.org/r/20200224095223.13361-10-mgorman@techsingularity.net

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 49b36d62cc35b6d3b08fc1a500b33916338708d8..87521acb3698b3424983f9a7d3c83a6bcde986a1 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5469,6 +5469,24 @@ static unsigned long cpu_runnable(struct rq *rq)
        return cfs_rq_runnable_avg(&rq->cfs);
 }
 
+static unsigned long cpu_runnable_without(struct rq *rq, struct task_struct *p)
+{
+       struct cfs_rq *cfs_rq;
+       unsigned int runnable;
+
+       /* Task has no contribution or is new */
+       if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
+               return cpu_runnable(rq);
+
+       cfs_rq = &rq->cfs;
+       runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
+
+       /* Discount task's runnable from CPU's runnable */
+       lsub_positive(&runnable, p->se.avg.runnable_avg);
+
+       return runnable;
+}
+
 static unsigned long capacity_of(int cpu)
 {
        return cpu_rq(cpu)->cpu_capacity;
@@ -7752,7 +7770,8 @@ struct sg_lb_stats {
        unsigned long avg_load; /*Avg load across the CPUs of the group */
        unsigned long group_load; /* Total load over the CPUs of the group */
        unsigned long group_capacity;
-       unsigned long group_util; /* Total utilization of the group */
+       unsigned long group_util; /* Total utilization over the CPUs of the group */
+       unsigned long group_runnable; /* Total runnable time over the CPUs of the group */
        unsigned int sum_nr_running; /* Nr of tasks running in the group */
        unsigned int sum_h_nr_running; /* Nr of CFS tasks running in the group */
        unsigned int idle_cpus;
@@ -7973,6 +7992,10 @@ group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
        if (sgs->sum_nr_running < sgs->group_weight)
                return true;
 
+       if ((sgs->group_capacity * imbalance_pct) <
+                       (sgs->group_runnable * 100))
+               return false;
+
        if ((sgs->group_capacity * 100) >
                        (sgs->group_util * imbalance_pct))
                return true;
@@ -7998,6 +8021,10 @@ group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
                        (sgs->group_util * imbalance_pct))
                return true;
 
+       if ((sgs->group_capacity * imbalance_pct) <
+                       (sgs->group_runnable * 100))
+               return true;
+
        return false;
 }
 
@@ -8092,6 +8119,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 
                sgs->group_load += cpu_load(rq);
                sgs->group_util += cpu_util(i);
+               sgs->group_runnable += cpu_runnable(rq);
                sgs->sum_h_nr_running += rq->cfs.h_nr_running;
 
                nr_running = rq->nr_running;
@@ -8367,6 +8395,7 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd,
 
                sgs->group_load += cpu_load_without(rq, p);
                sgs->group_util += cpu_util_without(i, p);
+               sgs->group_runnable += cpu_runnable_without(rq, p);
                local = task_running_on_cpu(i, p);
                sgs->sum_h_nr_running += rq->cfs.h_nr_running - local;