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authorJason Low <jason.low2@hp.com>2014-04-29 00:45:54 +0200
committerIngo Molnar <mingo@kernel.org>2014-05-07 11:51:36 +0200
commit0e5b5337f0da073e1f17aec3c322ea7826975d0d (patch)
tree3f47f8935bb09d489614f5d86421c84f92a40e73 /kernel/sched
parentsched: Skip double execution of pick_next_task_fair() (diff)
downloadlinux-0e5b5337f0da073e1f17aec3c322ea7826975d0d.tar.xz
linux-0e5b5337f0da073e1f17aec3c322ea7826975d0d.zip
sched: Fix updating rq->max_idle_balance_cost and rq->next_balance in idle_balance()
The following commit: e5fc66119ec9 ("sched: Fix race in idle_balance()") 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. Signed-off-by: Jason Low <jason.low2@hp.com> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: morten.rasmussen@arm.com Cc: aswin@hp.com Cc: daniel.lezcano@linaro.org Cc: alex.shi@linaro.org Cc: efault@gmx.de Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1398725155-7591-2-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7570dd969c28..0fdb96de81a5 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6653,6 +6653,7 @@ 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.
@@ -6705,14 +6706,16 @@ 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)) {
/*
@@ -6722,9 +6725,6 @@ 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 &&