From 1f74de8798c93ce14801cc4e772603e51c841c33 Mon Sep 17 00:00:00 2001 From: Quentin Perret Date: Mon, 3 Dec 2018 09:56:22 +0000 Subject: [PATCH] sched/toplogy: Introduce the 'sched_energy_present' static key In order to make sure Energy Aware Scheduling (EAS) will not impact systems where no Energy Model is available, introduce a static key guarding the access to EAS code. Since EAS is enabled on a per-root-domain basis, the static key is enabled when at least one root domain meets all conditions for EAS. Signed-off-by: Quentin Perret Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: adharmap@codeaurora.org Cc: chris.redpath@arm.com Cc: currojerez@riseup.net Cc: dietmar.eggemann@arm.com Cc: edubezval@gmail.com Cc: gregkh@linuxfoundation.org Cc: javi.merino@kernel.org Cc: joel@joelfernandes.org Cc: juri.lelli@redhat.com Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: pkondeti@codeaurora.org Cc: rjw@rjwysocki.net Cc: skannan@codeaurora.org Cc: smuckle@google.com Cc: srinivas.pandruvada@linux.intel.com Cc: thara.gopinath@linaro.org Cc: tkjos@google.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Cc: viresh.kumar@linaro.org Link: https://lkml.kernel.org/r/20181203095628.11858-10-quentin.perret@arm.com Signed-off-by: Ingo Molnar --- kernel/sched/sched.h | 4 ++++ kernel/sched/topology.c | 28 ++++++++++++++++++++++++---- 2 files changed, 28 insertions(+), 4 deletions(-) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index fd84900b0b21..2b3cf356e958 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2296,3 +2296,7 @@ unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned #else #define perf_domain_span(pd) NULL #endif + +#ifdef CONFIG_SMP +extern struct static_key_false sched_energy_present; +#endif diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 0a5a1d3a4eae..3f35ba1d8fde 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -201,6 +201,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) return 1; } +DEFINE_STATIC_KEY_FALSE(sched_energy_present); #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) DEFINE_MUTEX(sched_energy_mutex); bool sched_energy_update; @@ -273,6 +274,19 @@ static void destroy_perf_domain_rcu(struct rcu_head *rp) free_pd(pd); } +static void sched_energy_set(bool has_eas) +{ + if (!has_eas && static_branch_unlikely(&sched_energy_present)) { + if (sched_debug()) + pr_info("%s: stopping EAS\n", __func__); + static_branch_disable_cpuslocked(&sched_energy_present); + } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) { + if (sched_debug()) + pr_info("%s: starting EAS\n", __func__); + static_branch_enable_cpuslocked(&sched_energy_present); + } +} + /* * EAS can be used on a root domain if it meets all the following conditions: * 1. an Energy Model (EM) is available; @@ -299,7 +313,7 @@ static void destroy_perf_domain_rcu(struct rcu_head *rp) #define EM_MAX_COMPLEXITY 2048 extern struct cpufreq_governor schedutil_gov; -static void build_perf_domains(const struct cpumask *cpu_map) +static bool build_perf_domains(const struct cpumask *cpu_map) { int i, nr_pd = 0, nr_cs = 0, nr_cpus = cpumask_weight(cpu_map); struct perf_domain *pd = NULL, *tmp; @@ -365,7 +379,7 @@ static void build_perf_domains(const struct cpumask *cpu_map) if (tmp) call_rcu(&tmp->rcu, destroy_perf_domain_rcu); - return; + return !!pd; free: free_pd(pd); @@ -373,6 +387,8 @@ free: rcu_assign_pointer(rd->pd, NULL); if (tmp) call_rcu(&tmp->rcu, destroy_perf_domain_rcu); + + return false; } #else static void free_pd(struct perf_domain *pd) { } @@ -2114,6 +2130,7 @@ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], struct sched_domain_attr *dattr_new) { + bool __maybe_unused has_eas = false; int i, j, n; int new_topology; @@ -2177,14 +2194,17 @@ match2: for (i = 0; i < ndoms_new; i++) { for (j = 0; j < n && !sched_energy_update; j++) { if (cpumask_equal(doms_new[i], doms_cur[j]) && - cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) + cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) { + has_eas = true; goto match3; + } } /* No match - add perf. domains for a new rd */ - build_perf_domains(doms_new[i]); + has_eas |= build_perf_domains(doms_new[i]); match3: ; } + sched_energy_set(has_eas); #endif /* Remember the new sched domains: */