Commit-ID: df054e8445a4011e3d693c2268129c0456108663 Gitweb: https://git.kernel.org/tip/df054e8445a4011e3d693c2268129c0456108663 Author: Morten Rasmussen <[email protected]> AuthorDate: Wed, 4 Jul 2018 11:17:39 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 10 Sep 2018 11:05:48 +0200
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: Morten Rasmussen <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/sched/fair.c | 3 +++ kernel/sched/sched.h | 1 + kernel/sched/topology.c | 9 ++++++++- 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f808ddf2a868..3e5071aeb117 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4a2e8cae63c4..0f36adc31ba5 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -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; diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 5c4d583d53ee..b0cdf5e95bda 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -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);
