From: Morten Rasmussen <morten.rasmussen@arm.com>
To: peterz@infradead.org, mingo@redhat.com
Cc: dietmar.eggemann@arm.com, yuyang.du@intel.com,
vincent.guittot@linaro.org, mgalbraith@suse.de,
sgurrappadi@nvidia.com, freedom.tan@mediatek.com,
keita.kobayashi.ym@renesas.com, linux-kernel@vger.kernel.org,
Morten Rasmussen <morten.rasmussen@arm.com>,
Rik van Riel <riel@redhat.com>
Subject: [PATCH v3 02/13] sched/fair: Consistent use of prev_cpu in wakeup path
Date: Mon, 25 Jul 2016 14:34:19 +0100 [thread overview]
Message-ID: <1469453670-2660-3-git-send-email-morten.rasmussen@arm.com> (raw)
In-Reply-To: <1469453670-2660-1-git-send-email-morten.rasmussen@arm.com>
In commit ac66f5477239 ("sched/numa: Introduce migrate_swap()")
select_task_rq() got a 'cpu' argument to enable overriding of prev_cpu
in special cases (NUMA task swapping). However, the
select_task_rq_fair() helper functions: wake_affine() and
select_idle_sibling(), still use task_cpu(p) directly to work out
prev_cpu which leads to inconsistencies.
This patch passes prev_cpu (potentially overridden by NUMA code) into
the helper functions to ensure prev_cpu is indeed the same cpu
everywhere in the wakeup path.
cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
---
kernel/sched/fair.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4088eedea763..e7d50acd6028 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -656,7 +656,7 @@ static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
}
#ifdef CONFIG_SMP
-static int select_idle_sibling(struct task_struct *p, int cpu);
+static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu);
static unsigned long task_h_load(struct task_struct *p);
/*
@@ -1514,7 +1514,8 @@ static void task_numa_compare(struct task_numa_env *env,
* Call select_idle_sibling to maybe find a better one.
*/
if (!cur)
- env->dst_cpu = select_idle_sibling(env->p, env->dst_cpu);
+ env->dst_cpu = select_idle_sibling(env->p, env->src_cpu,
+ env->dst_cpu);
assign:
task_numa_assign(env, cur, imp);
@@ -5091,18 +5092,18 @@ static int wake_wide(struct task_struct *p)
return 1;
}
-static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
+static int wake_affine(struct sched_domain *sd, struct task_struct *p,
+ int prev_cpu, int sync)
{
s64 this_load, load;
s64 this_eff_load, prev_eff_load;
- int idx, this_cpu, prev_cpu;
+ int idx, this_cpu;
struct task_group *tg;
unsigned long weight;
int balanced;
idx = sd->wake_idx;
this_cpu = smp_processor_id();
- prev_cpu = task_cpu(p);
load = source_load(prev_cpu, idx);
this_load = target_load(this_cpu, idx);
@@ -5267,11 +5268,10 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
/*
* Try and locate an idle CPU in the sched_domain.
*/
-static int select_idle_sibling(struct task_struct *p, int target)
+static int select_idle_sibling(struct task_struct *p, int prev, int target)
{
struct sched_domain *sd;
struct sched_group *sg;
- int i = task_cpu(p);
if (idle_cpu(target))
return target;
@@ -5279,8 +5279,8 @@ static int select_idle_sibling(struct task_struct *p, int target)
/*
* If the prevous cpu is cache affine and idle, don't be stupid.
*/
- if (i != target && cpus_share_cache(i, target) && idle_cpu(i))
- return i;
+ if (prev != target && cpus_share_cache(prev, target) && idle_cpu(prev))
+ return prev;
/*
* Otherwise, iterate the domains and find an eligible idle cpu.
@@ -5301,6 +5301,8 @@ static int select_idle_sibling(struct task_struct *p, int target)
for_each_lower_domain(sd) {
sg = sd->groups;
do {
+ int i;
+
if (!cpumask_intersects(sched_group_cpus(sg),
tsk_cpus_allowed(p)))
goto next;
@@ -5409,13 +5411,13 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
if (affine_sd) {
sd = NULL; /* Prefer wake_affine over balance flags */
- if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
+ if (cpu != prev_cpu && wake_affine(affine_sd, p, prev_cpu, sync))
new_cpu = cpu;
}
if (!sd) {
if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */
- new_cpu = select_idle_sibling(p, new_cpu);
+ new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
} else while (sd) {
struct sched_group *group;
--
1.9.1
next prev parent reply other threads:[~2016-07-25 13:37 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-25 13:34 [PATCH v3 00/13] sched: Clean-ups and asymmetric cpu capacity support Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 01/13] sched: Fix power to capacity renaming in comment Morten Rasmussen
2016-07-25 13:34 ` Morten Rasmussen [this message]
2016-07-25 13:34 ` [PATCH v3 03/13] sched/fair: Optimize find_idlest_cpu() when there is no choice Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 04/13] sched/core: Remove unnecessary null-pointer check Morten Rasmussen
2016-08-18 10:56 ` [tip:sched/core] sched/core: Remove unnecessary NULL-pointer check tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 05/13] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Morten Rasmussen
2016-08-15 10:54 ` Peter Zijlstra
2016-08-15 11:43 ` Morten Rasmussen
2016-08-18 10:56 ` [tip:sched/core] sched/core: Clarify SD_flags comment tip-bot for Peter Zijlstra
2016-08-17 8:42 ` [PATCH v3 05/13] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Wanpeng Li
2016-08-17 9:23 ` Morten Rasmussen
2016-08-17 9:26 ` Wanpeng Li
2016-08-18 10:56 ` [tip:sched/core] sched/core: " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 06/13] sched/core: Pass child domain into sd_init Morten Rasmussen
2016-08-18 10:57 ` [tip:sched/core] sched/core: Pass child domain into sd_init() tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 07/13] sched: Enable SD_BALANCE_WAKE for asymmetric capacity systems Morten Rasmussen
2016-08-18 10:57 ` [tip:sched/core] sched/core: " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 08/13] sched: Store maximum per-cpu capacity in root domain Morten Rasmussen
2016-08-01 18:53 ` Dietmar Eggemann
2016-08-16 12:24 ` Vincent Guittot
2016-08-18 10:58 ` [tip:sched/core] sched/core: Store maximum per-CPU " tip-bot for Dietmar Eggemann
2016-07-25 13:34 ` [PATCH v3 09/13] sched/fair: Let asymmetric cpu configurations balance at wake-up Morten Rasmussen
2016-08-15 13:39 ` Peter Zijlstra
2016-08-15 15:01 ` Morten Rasmussen
2016-08-15 15:10 ` Peter Zijlstra
2016-08-15 15:30 ` Morten Rasmussen
2016-08-18 10:58 ` [tip:sched/core] sched/fair: Let asymmetric CPU " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 10/13] sched/fair: Compute task/cpu utilization at wake-up more correctly Morten Rasmussen
2016-08-15 14:23 ` Peter Zijlstra
2016-08-15 15:42 ` Morten Rasmussen
2016-08-18 8:40 ` Morten Rasmussen
2016-08-18 10:24 ` Morten Rasmussen
2016-08-18 11:46 ` Wanpeng Li
2016-08-18 13:45 ` Morten Rasmussen
2016-08-19 1:43 ` Wanpeng Li
2016-08-19 14:03 ` Morten Rasmussen
2016-08-22 1:48 ` Wanpeng Li
2016-08-22 11:29 ` Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 11/13] sched/fair: Consider spare capacity in find_idlest_group() Morten Rasmussen
2016-08-16 13:57 ` Vincent Guittot
2016-08-18 11:16 ` Morten Rasmussen
2016-08-18 12:28 ` Peter Zijlstra
2016-07-25 13:34 ` [PATCH v3 12/13] sched: Add per-cpu min capacity to sched_group_capacity Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 13/13] sched/fair: Avoid pulling tasks from non-overloaded higher capacity groups Morten Rasmussen
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