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 1/5] sched/fair: Move select_task_rq_fair slow-path into its own function
Date: Fri, 25 Aug 2017 11:16:28 +0100 [thread overview]
Message-ID: <20170825101632.28065-2-brendan.jackman@arm.com> (raw)
In-Reply-To: <20170825101632.28065-1-brendan.jackman@arm.com>
In preparation for changes that would otherwise require adding a new
level of indentation to the while(sd) loop, create a new function
find_idlest_cpu which contains this loop, and rename the existing
find_idlest_cpu to find_idlest_group_cpu.
Code inside the while(sd) loop is unchanged. @new_cpu is added as a
variable in the new function, with the same initial value as the
@new_cpu in select_task_rq_fair.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
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>
squash! sched/fair: Move select_task_rq_fair slow-path into its own function
---
kernel/sched/fair.c | 83 +++++++++++++++++++++++++++++++----------------------
1 file changed, 48 insertions(+), 35 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c95880e216f6..f6e277c65235 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5509,10 +5509,10 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
}
/*
- * find_idlest_cpu - find the idlest cpu among the cpus in group.
+ * find_idlest_group_cpu - find the idlest cpu among the cpus in group.
*/
static int
-find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
+find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
{
unsigned long load, min_load = ULONG_MAX;
unsigned int min_exit_latency = UINT_MAX;
@@ -5561,6 +5561,50 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
}
+static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p,
+ int cpu, int prev_cpu, int sd_flag)
+{
+ int new_cpu = prev_cpu;
+
+ while (sd) {
+ struct sched_group *group;
+ struct sched_domain *tmp;
+ int weight;
+
+ if (!(sd->flags & sd_flag)) {
+ sd = sd->child;
+ continue;
+ }
+
+ group = find_idlest_group(sd, p, cpu, sd_flag);
+ if (!group) {
+ sd = sd->child;
+ continue;
+ }
+
+ new_cpu = find_idlest_group_cpu(group, p, cpu);
+ if (new_cpu == -1 || new_cpu == cpu) {
+ /* Now try balancing at a lower domain level of cpu */
+ sd = sd->child;
+ continue;
+ }
+
+ /* Now try balancing at a lower domain level of new_cpu */
+ cpu = new_cpu;
+ weight = sd->span_weight;
+ sd = NULL;
+ for_each_domain(cpu, tmp) {
+ if (weight <= tmp->span_weight)
+ break;
+ if (tmp->flags & sd_flag)
+ sd = tmp;
+ }
+ /* while loop will break here if sd == NULL */
+ }
+
+ return new_cpu;
+}
+
#ifdef CONFIG_SCHED_SMT
static inline void set_idle_cores(int cpu, int val)
@@ -5918,39 +5962,8 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */
new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
- } else while (sd) {
- struct sched_group *group;
- int weight;
-
- if (!(sd->flags & sd_flag)) {
- sd = sd->child;
- continue;
- }
-
- group = find_idlest_group(sd, p, cpu, sd_flag);
- if (!group) {
- sd = sd->child;
- continue;
- }
-
- new_cpu = find_idlest_cpu(group, p, cpu);
- if (new_cpu == -1 || new_cpu == cpu) {
- /* Now try balancing at a lower domain level of cpu */
- sd = sd->child;
- continue;
- }
-
- /* Now try balancing at a lower domain level of new_cpu */
- cpu = new_cpu;
- weight = sd->span_weight;
- sd = NULL;
- for_each_domain(cpu, tmp) {
- if (weight <= tmp->span_weight)
- break;
- if (tmp->flags & sd_flag)
- sd = tmp;
- }
- /* while loop will break here if sd == NULL */
+ } else {
+ new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
}
rcu_read_unlock();
--
2.14.1
next prev 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 ` Brendan Jackman [this message]
2017-08-25 12:22 ` [PATCH v2 1/5] sched/fair: Move select_task_rq_fair slow-path into its own function 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 ` [PATCH v2 3/5] sched/fair: Fix find_idlest_group when local group is not allowed Brendan Jackman
2017-08-25 13:39 ` 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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