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From: Brendan Jackman <brendan.jackman@arm.com>
To: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org
Cc: Joel Fernandes <joelaf@google.com>,
	Andres Oportus <andresoportus@google.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Josef Bacik <josef@toxicpanda.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>
Subject: [PATCH v2 3/5] sched/fair: Fix find_idlest_group when local group is not allowed
Date: Fri, 25 Aug 2017 11:16:30 +0100	[thread overview]
Message-ID: <20170825101632.28065-4-brendan.jackman@arm.com> (raw)
In-Reply-To: <20170825101632.28065-1-brendan.jackman@arm.com>

When the local group is not allowed we do not modify this_*_load from
their initial value of 0. That means that the load checks at the end
of find_idlest_group cause us to incorrectly return NULL. Fixing the
initial values to ULONG_MAX means we will instead return the idlest
remote group in that case.

Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 kernel/sched/fair.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4ccecbf825bf..0ce75bbcde45 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5387,8 +5387,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
 {
 	struct sched_group *idlest = NULL, *group = sd->groups;
 	struct sched_group *most_spare_sg = NULL;
-	unsigned long min_runnable_load = ULONG_MAX, this_runnable_load = 0;
-	unsigned long min_avg_load = ULONG_MAX, this_avg_load = 0;
+	unsigned long min_runnable_load = ULONG_MAX;
+	unsigned long this_runnable_load = ULONG_MAX;
+	unsigned long min_avg_load = ULONG_MAX, this_avg_load = ULONG_MAX;
 	unsigned long most_spare = 0, this_spare = 0;
 	int load_idx = sd->forkexec_idx;
 	int imbalance_scale = 100 + (sd->imbalance_pct-100)/2;
-- 
2.14.1

  parent reply	other threads:[~2017-08-25 10:17 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-25 10:16 [PATCH v2 0/5] sched/fair: Tweaks for select_task_rq_fair slowpath Brendan Jackman
2017-08-25 10:16 ` [PATCH v2 1/5] sched/fair: Move select_task_rq_fair slow-path into its own function Brendan Jackman
2017-08-25 12:22   ` Josef Bacik
2017-08-25 13:40   ` Vincent Guittot
2017-08-25 10:16 ` [PATCH v2 2/5] sched/fair: Remove unnecessary comparison with -1 Brendan Jackman
2017-08-25 12:44   ` Josef Bacik
2017-08-25 13:40   ` Vincent Guittot
2017-08-25 10:16 ` Brendan Jackman [this message]
2017-08-25 13:39   ` [PATCH v2 3/5] sched/fair: Fix find_idlest_group when local group is not allowed Vincent Guittot
2017-08-25 10:16 ` [PATCH v2 4/5] sched/fair: Fix use of find_idlest_group when no groups are allowed Brendan Jackman
2017-08-25 13:39   ` Vincent Guittot
2017-08-25 10:16 ` [PATCH v2 5/5] sched/fair: Fix use of find_idlest_group when local group is idlest Brendan Jackman
2017-08-25 13:38   ` Vincent Guittot
2017-08-25 15:51     ` Brendan Jackman
2017-08-28  8:56       ` Vincent Guittot
2017-08-28  9:11         ` Vincent Guittot
2017-08-29 17:09         ` Brendan Jackman

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