Commit-ID: cd92bfd3b8cb0ec2ee825e55a3aee704cd55aea9
Gitweb: http://git.kernel.org/tip/cd92bfd3b8cb0ec2ee825e55a3aee704cd55aea9
Author: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
AuthorDate: Mon, 1 Aug 2016 19:53:35 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 18 Aug 2016 11:26:55 +0200
sched/core: Store maximum per-CPU capacity in root domain
To be able to compare the capacity of the target CPU with the highest
available CPU capacity, store the maximum per-CPU capacity in the root
domain.
The max per-CPU capacity should be 1024 for all systems except SMT,
where the capacity is currently based on smt_gain and the number of
hardware threads and is <1024. If SMT can be brought to work with a
per-thread capacity of 1024, this patch can be dropped and replaced by a
hard-coded max capacity of 1024 (=SCHED_CAPACITY_SCALE).
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Signed-off-by: Morten Rasmussen <morten.rasmussen@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: freedom.tan@xxxxxxxxxxxx
Cc: keita.kobayashi.ym@xxxxxxxxxxx
Cc: mgalbraith@xxxxxxx
Cc: sgurrappadi@xxxxxxxxxx
Cc: vincent.guittot@xxxxxxxxxx
Cc: yuyang.du@xxxxxxxxx
Link: http://lkml.kernel.org/r/26c69258-9947-f830-a53e-0c54e7750646@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/core.c | 12 ++++++++++++
kernel/sched/sched.h | 2 ++
2 files changed, 14 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4695df6..6924314 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6903,6 +6903,7 @@ static int build_sched_domains(const struct cpumask *cpu_map,
enum s_alloc alloc_state;
struct sched_domain *sd;
struct s_data d;
+ struct rq *rq = NULL;
int i, ret = -ENOMEM;
alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
@@ -6953,11 +6954,22 @@ static int build_sched_domains(const struct cpumask *cpu_map,
/* Attach the domains */
rcu_read_lock();
for_each_cpu(i, cpu_map) {
+ rq = cpu_rq(i);
sd = *per_cpu_ptr(d.sd, i);
+
+ /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
+ if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
+ WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
+
cpu_attach_domain(sd, d.rd, i);
}
rcu_read_unlock();
+ if (rq) {
+ pr_info("span: %*pbl (max cpu_capacity = %lu)\n",
+ cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
+ }
+
ret = 0;
error:
__free_domain_allocs(&d, alloc_state, cpu_map);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index afe76d0..420c05d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -565,6 +565,8 @@ struct root_domain {
*/
cpumask_var_t rto_mask;
struct cpupri cpupri;
+
+ unsigned long max_cpu_capacity;
};
extern struct root_domain def_root_domain;
--
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