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Commit df054e84 authored by Morten Rasmussen's avatar Morten Rasmussen Committed by Ingo Molnar
Browse files

sched/topology: Add static_key for asymmetric CPU capacity optimizations 



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: default avatarMorten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: default avatarPeter 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: default avatarIngo Molnar <mingo@kernel.org>
parent e1799a80

kernel/sched/fair.c

+3 −0
Original line number Diff line number Diff line
@@ -6188,6 +6188,9 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu) 
{

	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));

	max_cap = cpu_rq(cpu)->rd->max_cpu_capacity;

kernel/sched/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -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 *, sd_numa);

DECLARE_PER_CPU(struct sched_domain *, sd_asym);

extern struct static_key_false sched_asym_cpucapacity;



struct sched_group_capacity {

	atomic_t		ref;

kernel/sched/topology.c

+8 −1
Original line number Diff line number Diff line
@@ -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 *, sd_numa);

DEFINE_PER_CPU(struct sched_domain *, sd_asym);

DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);



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;

	int i, ret = -ENOMEM;

	struct sched_domain_topology_level *tl_asym;

	bool has_asym = false;



	alloc_state = __visit_domain_allocation_hell(&d, cpu_map);

	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) {

			int dflags = 0;



			if (tl == tl_asym)

			if (tl == tl_asym) {

				dflags |= SD_ASYM_CPUCAPACITY;

				has_asym = true;

			}



			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();



	if (has_asym)

		static_branch_enable_cpuslocked(&sched_asym_cpucapacity);



	if (rq && sched_debug_enabled) {

		pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",

			cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);