Commit e5fc6611 can potentially cause rq->max_idle_balance_cost to not be
updated, even when load_balance(NEWLY_IDLE) is attempted and the per-sd
max cost value is updated.
Preeti noticed a similar issue with updating rq->next_balance.
In this patch, we fix this by making sure we still check/update those values
even if a task gets enqueued while browsing the domains.
Cc: daniel.lezc...@linaro.org
Cc: alex....@linaro.org
Cc: efa...@gmx.de
Cc: vincent.guit...@linaro.org
Cc: morten.rasmus...@arm.com
Cc: as...@hp.com
Cc: mi...@kernel.org
Reviewed-by: Preeti U Murthy <pre...@linux.vnet.ibm.com>
Signed-off-by: Jason Low <jason.l...@hp.com>
---
kernel/sched/fair.c | 16 ++++++++--------
1 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index af47873..e0f3019 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6658,6 +6658,7 @@ static int idle_balance(struct rq *this_rq)
int this_cpu = this_rq->cpu;
idle_enter_fair(this_rq);
+
/*
* We must set idle_stamp _before_ calling idle_balance(), such that we
* measure the duration of idle_balance() as idle time.
@@ -6714,14 +6715,16 @@ static int idle_balance(struct rq *this_rq)
raw_spin_lock(&this_rq->lock);
+ if (curr_cost > this_rq->max_idle_balance_cost)
+ this_rq->max_idle_balance_cost = curr_cost;
+
/*
- * While browsing the domains, we released the rq lock.
- * A task could have be enqueued in the meantime
+ * While browsing the domains, we released the rq lock, a task could
+ * have been enqueued in the meantime. Since we're not going idle,
+ * pretend we pulled a task.
*/
- if (this_rq->cfs.h_nr_running && !pulled_task) {
+ if (this_rq->cfs.h_nr_running && !pulled_task)
pulled_task = 1;
- goto out;
- }
if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
/*
@@ -6731,9 +6734,6 @@ static int idle_balance(struct rq *this_rq)
this_rq->next_balance = next_balance;
}
- if (curr_cost > this_rq->max_idle_balance_cost)
- this_rq->max_idle_balance_cost = curr_cost;
-
out:
/* Is there a task of a high priority class? */
if (this_rq->nr_running != this_rq->cfs.h_nr_running)
--
1.7.1
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