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sched/fair: Force gold cpus to do idle lb when silver has big tasks

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We often see traces that gold cpus goes to idle even when silver
has big tasks. This is because avg_idle checks does not allow
the gold cpus to enter idle balance. This is NOT okay when
silver CPUs have big tasks.

Change-Id: Ice00d43c70be105b5bc3ad09caa6047aa98d7402
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Runmin Wang <runminw@codeaurora.org>
This commit is contained in:
Pavankumar Kondeti 2019-04-02 10:48:54 -07:00 committed by Gerrit - the friendly Code Review server
parent 041ae774be
commit 5250fc5df0
1 changed files with 19 additions and 3 deletions
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22
kernel/sched/fair.c
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@ -11549,6 +11549,20 @@ static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle
static inline void nohz_newidle_balance(struct rq *this_rq) { }
#endif /* CONFIG_NO_HZ_COMMON */
static bool silver_has_big_tasks(void)
{
int cpu;
for_each_possible_cpu(cpu) {
if (!is_min_capacity_cpu(cpu))
break;
if (cpu_rq(cpu)->walt_stats.nr_big_tasks)
return true;
}
return false;
}
/*
* idle_balance is called by schedule() if this_cpu is about to become
* idle. Attempts to pull tasks from other CPUs.
@ -11560,6 +11574,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
struct sched_domain *sd;
int pulled_task = 0;
u64 curr_cost = 0;
u64 avg_idle = this_rq->avg_idle;
if (cpu_isolated(this_cpu))
return 0;
@ -11575,7 +11590,8 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
*/
if (!cpu_active(this_cpu))
return 0;
if (!is_min_capacity_cpu(this_cpu) && silver_has_big_tasks())
avg_idle = ULLONG_MAX;
/*
* This is OK, because current is on_cpu, which avoids it being picked
* for load-balance and preemption/IRQs are still disabled avoiding
@ -11584,7 +11600,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
*/
rq_unpin_lock(this_rq, rf);
if (this_rq->avg_idle < sysctl_sched_migration_cost ||
if (avg_idle < sysctl_sched_migration_cost ||
!READ_ONCE(this_rq->rd->overload)) {
rcu_read_lock();
@ -11609,7 +11625,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
if (!(sd->flags & SD_LOAD_BALANCE))
continue;
if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
if (avg_idle < curr_cost + sd->max_newidle_lb_cost) {
update_next_balance(sd, &next_balance);
break;
}