From: Vincent Guittot <vincent.guittot@linaro.org>
To: linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org
Cc: pauld@redhat.com, valentin.schneider@arm.com,
srikar@linux.vnet.ibm.com, quentin.perret@arm.com,
dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com,
hdanton@sina.com, parth@linux.ibm.com, riel@surriel.com,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH v4 07/11] sched/fair: evenly spread tasks when not overloaded
Date: Fri, 18 Oct 2019 15:26:34 +0200 [thread overview]
Message-ID: <1571405198-27570-8-git-send-email-vincent.guittot@linaro.org> (raw)
In-Reply-To: <1571405198-27570-1-git-send-email-vincent.guittot@linaro.org>
When there is only 1 cpu per group, using the idle cpus to evenly spread
tasks doesn't make sense and nr_running is a better metrics.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
kernel/sched/fair.c | 40 ++++++++++++++++++++++++++++------------
1 file changed, 28 insertions(+), 12 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9ac2264..9b8e20d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8601,18 +8601,34 @@ static struct sched_group *find_busiest_group(struct lb_env *env)
busiest->sum_nr_running > local->sum_nr_running + 1)
goto force_balance;
- if (busiest->group_type != group_overloaded &&
- (env->idle == CPU_NOT_IDLE ||
- local->idle_cpus <= (busiest->idle_cpus + 1)))
- /*
- * If the busiest group is not overloaded
- * and there is no imbalance between this and busiest group
- * wrt idle CPUs, it is balanced. The imbalance
- * becomes significant if the diff is greater than 1 otherwise
- * we might end up to just move the imbalance on another
- * group.
- */
- goto out_balanced;
+ if (busiest->group_type != group_overloaded) {
+ if (env->idle == CPU_NOT_IDLE)
+ /*
+ * If the busiest group is not overloaded (and as a
+ * result the local one too) but this cpu is already
+ * busy, let another idle cpu try to pull task.
+ */
+ goto out_balanced;
+
+ if (busiest->group_weight > 1 &&
+ local->idle_cpus <= (busiest->idle_cpus + 1))
+ /*
+ * If the busiest group is not overloaded
+ * and there is no imbalance between this and busiest
+ * group wrt idle CPUs, it is balanced. The imbalance
+ * becomes significant if the diff is greater than 1
+ * otherwise we might end up to just move the imbalance
+ * on another group. Of course this applies only if
+ * there is more than 1 CPU per group.
+ */
+ goto out_balanced;
+
+ if (busiest->sum_h_nr_running == 1)
+ /*
+ * busiest doesn't have any tasks waiting to run
+ */
+ goto out_balanced;
+ }
force_balance:
/* Looks like there is an imbalance. Compute it */
--
2.7.4
next prev parent reply other threads:[~2019-10-18 13:27 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 13:26 [PATCH v4 00/10] sched/fair: rework the CFS load balance Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 01/11] sched/fair: clean up asym packing Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Clean " tip-bot2 for Vincent Guittot
2019-10-30 14:51 ` [PATCH v4 01/11] sched/fair: clean " Mel Gorman
2019-10-30 16:03 ` Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 02/11] sched/fair: rename sum_nr_running to sum_h_nr_running Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Rename sg_lb_stats::sum_nr_running " tip-bot2 for Vincent Guittot
2019-10-30 14:53 ` [PATCH v4 02/11] sched/fair: rename sum_nr_running " Mel Gorman
2019-10-18 13:26 ` [PATCH v4 03/11] sched/fair: remove meaningless imbalance calculation Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Remove " tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 04/11] sched/fair: rework load_balance Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Rework load_balance() tip-bot2 for Vincent Guittot
2019-10-30 15:45 ` [PATCH v4 04/11] sched/fair: rework load_balance Mel Gorman
2019-10-30 16:16 ` Valentin Schneider
2019-10-31 9:09 ` Vincent Guittot
2019-10-31 10:15 ` Mel Gorman
2019-10-31 11:13 ` Vincent Guittot
2019-10-31 11:40 ` Mel Gorman
2019-11-08 16:35 ` Vincent Guittot
2019-11-08 18:37 ` Mel Gorman
2019-11-12 10:58 ` Vincent Guittot
2019-11-12 15:06 ` Mel Gorman
2019-11-12 15:40 ` Vincent Guittot
2019-11-12 17:45 ` Mel Gorman
2019-11-18 13:50 ` Ingo Molnar
2019-11-18 13:57 ` Vincent Guittot
2019-11-18 14:51 ` Mel Gorman
2019-10-18 13:26 ` [PATCH v4 05/11] sched/fair: use rq->nr_running when balancing load Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use " tip-bot2 for Vincent Guittot
2019-10-30 15:54 ` [PATCH v4 05/11] sched/fair: use " Mel Gorman
2019-10-18 13:26 ` [PATCH v4 06/11] sched/fair: use load instead of runnable load in load_balance Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use load instead of runnable load in load_balance() tip-bot2 for Vincent Guittot
2019-10-30 15:58 ` [PATCH v4 06/11] sched/fair: use load instead of runnable load in load_balance Mel Gorman
2019-10-18 13:26 ` Vincent Guittot [this message]
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Spread out tasks evenly when not overloaded tip-bot2 for Vincent Guittot
2019-10-30 16:03 ` [PATCH v4 07/11] sched/fair: evenly spread tasks " Mel Gorman
2019-10-18 13:26 ` [PATCH v4 08/11] sched/fair: use utilization to select misfit task Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use " tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 09/11] sched/fair: use load instead of runnable load in wakeup path Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Use " tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 10/11] sched/fair: optimize find_idlest_group Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Optimize find_idlest_group() tip-bot2 for Vincent Guittot
2019-10-18 13:26 ` [PATCH v4 11/11] sched/fair: rework find_idlest_group Vincent Guittot
2019-10-21 9:12 ` [tip: sched/core] sched/fair: Rework find_idlest_group() tip-bot2 for Vincent Guittot
2019-10-22 16:46 ` [PATCH] sched/fair: fix rework of find_idlest_group() Vincent Guittot
2019-10-23 7:50 ` Chen, Rong A
2019-10-30 16:07 ` Mel Gorman
2019-11-18 17:42 ` [tip: sched/core] sched/fair: Fix " tip-bot2 for Vincent Guittot
2019-11-22 14:37 ` [PATCH] sched/fair: fix " Valentin Schneider
2019-11-25 9:16 ` Vincent Guittot
2019-11-25 11:03 ` Valentin Schneider
2019-11-20 11:58 ` [PATCH v4 11/11] sched/fair: rework find_idlest_group Qais Yousef
2019-11-20 13:21 ` Vincent Guittot
2019-11-20 16:53 ` Vincent Guittot
2019-11-20 17:34 ` Qais Yousef
2019-11-20 17:43 ` Vincent Guittot
2019-11-20 18:10 ` Qais Yousef
2019-11-20 18:20 ` Vincent Guittot
2019-11-20 18:27 ` Qais Yousef
2019-11-20 19:28 ` Vincent Guittot
2019-11-20 19:55 ` Qais Yousef
2019-11-21 14:58 ` Qais Yousef
2019-11-22 14:34 ` Valentin Schneider
2019-11-25 9:59 ` Vincent Guittot
2019-11-25 11:13 ` Valentin Schneider
2019-10-21 7:50 ` [PATCH v4 00/10] sched/fair: rework the CFS load balance Ingo Molnar
2019-10-21 8:44 ` Vincent Guittot
2019-10-21 12:56 ` Phil Auld
2019-10-24 12:38 ` Phil Auld
2019-10-24 13:46 ` Phil Auld
2019-10-24 14:59 ` Vincent Guittot
2019-10-25 13:33 ` Phil Auld
2019-10-28 13:03 ` Vincent Guittot
2019-10-30 14:39 ` Phil Auld
2019-10-30 16:24 ` Dietmar Eggemann
2019-10-30 16:35 ` Valentin Schneider
2019-10-30 17:19 ` Phil Auld
2019-10-30 17:25 ` Valentin Schneider
2019-10-30 17:29 ` Phil Auld
2019-10-30 17:28 ` Vincent Guittot
2019-10-30 17:44 ` Phil Auld
2019-10-30 17:25 ` Vincent Guittot
2019-10-31 13:57 ` Phil Auld
2019-10-31 16:41 ` Vincent Guittot
2019-10-30 16:24 ` Mel Gorman
2019-10-30 16:35 ` Vincent Guittot
2019-11-18 13:15 ` Ingo Molnar
2019-11-25 12:48 ` Valentin Schneider
2020-01-03 16:39 ` Valentin Schneider
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