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sched/topology: Add static_key for asymmetric CPU capacity optimizations

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The existing asymmetric CPU capacity code should cause minimal overhead
for others. Putting it behind a static_key, it has been done for SMT
optimizations, would make it easier to extend and improve without
causing harm to others moving forward.

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-2-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Morten Rasmussen 2018-07-04 11:17:39 +01:00 • committed by Ingo Molnar
parent e1799a80a4
commit df054e8445
3 changed files with 12 additions and 1 deletions
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3
kernel/sched/fair.c
View file

@ -6188,6 +6188,9 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
{ {
long min_cap, max_cap; long min_cap, max_cap;
if (!static_branch_unlikely(&sched_asym_cpucapacity))
return 0;
min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu)); min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu));
max_cap = cpu_rq(cpu)->rd->max_cpu_capacity; max_cap = cpu_rq(cpu)->rd->max_cpu_capacity;

1
kernel/sched/sched.h
View file

@ -1185,6 +1185,7 @@ DECLARE_PER_CPU(int, sd_llc_id);
DECLARE_PER_CPU(struct sched_domain_shared *, sd_llc_shared); DECLARE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
DECLARE_PER_CPU(struct sched_domain *, sd_numa); DECLARE_PER_CPU(struct sched_domain *, sd_numa);
DECLARE_PER_CPU(struct sched_domain *, sd_asym); DECLARE_PER_CPU(struct sched_domain *, sd_asym);
extern struct static_key_false sched_asym_cpucapacity;
struct sched_group_capacity { struct sched_group_capacity {
atomic_t ref; atomic_t ref;

9
kernel/sched/topology.c
View file

@ -398,6 +398,7 @@ DEFINE_PER_CPU(int, sd_llc_id);
DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared); DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
DEFINE_PER_CPU(struct sched_domain *, sd_numa); DEFINE_PER_CPU(struct sched_domain *, sd_numa);
DEFINE_PER_CPU(struct sched_domain *, sd_asym); DEFINE_PER_CPU(struct sched_domain *, sd_asym);
DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
static void update_top_cache_domain(int cpu) static void update_top_cache_domain(int cpu)
{ {
@ -1705,6 +1706,7 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
struct rq *rq = NULL; struct rq *rq = NULL;
int i, ret = -ENOMEM; int i, ret = -ENOMEM;
struct sched_domain_topology_level *tl_asym; struct sched_domain_topology_level *tl_asym;
bool has_asym = false;
alloc_state = __visit_domain_allocation_hell(&d, cpu_map); alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
if (alloc_state != sa_rootdomain) if (alloc_state != sa_rootdomain)
@ -1720,8 +1722,10 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
for_each_sd_topology(tl) { for_each_sd_topology(tl) {
int dflags = 0; int dflags = 0;
if (tl == tl_asym) if (tl == tl_asym) {
dflags |= SD_ASYM_CPUCAPACITY; dflags |= SD_ASYM_CPUCAPACITY;
has_asym = true;
}
sd = build_sched_domain(tl, cpu_map, attr, sd, dflags, i); sd = build_sched_domain(tl, cpu_map, attr, sd, dflags, i);
@ -1773,6 +1777,9 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
} }
rcu_read_unlock(); rcu_read_unlock();
if (has_asym)
static_branch_enable_cpuslocked(&sched_asym_cpucapacity);
if (rq && sched_debug_enabled) { if (rq && sched_debug_enabled) {
pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n", pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);