From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Chen Subject: [PATCH v8 1/8] sched: Extend scheduler's asym packing Date: Tue, 22 Nov 2016 12:23:53 -0800 Message-ID: <0e73ae12737dfaafa46c07066cc7c5d3f1675e46.1479844244.git.tim.c.chen@linux.intel.com> References: Return-path: In-Reply-To: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org To: rjw@rjwysocki.net, tglx@linutronix.de, mingo@redhat.com, bp@suse.de Cc: Tim Chen , x86@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, peterz@infradead.org, jolsa@redhat.com, Srinivas Pandruvada List-Id: linux-acpi@vger.kernel.org We generalize the scheduler's asym packing to provide an ordering of the cpu beyond just the cpu number. This allows the use of the ASYM_PACKING scheduler machinery to move loads to preferred CPU in a sched domain. The preference is defined with the cpu priority given by arch_asym_cpu_priority(cpu). We also record the most preferred cpu in a sched group when we build the cpu's capacity for fast lookup of preferred cpu during load balancing. Co-developed-by: Peter Zijlstra (Intel) Signed-off-by: Tim Chen --- include/linux/sched.h | 4 ++++ kernel/sched/core.c | 15 ++++++++++++++ kernel/sched/fair.c | 54 +++++++++++++++++++++++++++++++++++---------------- kernel/sched/sched.h | 6 ++++++ 4 files changed, 62 insertions(+), 17 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 348f51b..ca02475 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1057,6 +1057,10 @@ static inline int cpu_numa_flags(void) } #endif +int arch_asym_cpu_priority(int cpu); +int arch_asym_max_cpu_and(const struct cpumask *mask1, + const struct cpumask *mask2); + struct sched_domain_attr { int relax_domain_level; }; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 154fd68..d54c6e1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6301,7 +6301,22 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) WARN_ON(!sg); do { + int cpu, max_cpu = -1; + sg->group_weight = cpumask_weight(sched_group_cpus(sg)); + + if (!(sd->flags & SD_ASYM_PACKING)) + goto next; + + for_each_cpu(cpu, sched_group_cpus(sg)) { + if (max_cpu < 0) + max_cpu = cpu; + else if (sched_asym_prefer(cpu, max_cpu)) + max_cpu = cpu; + } + sg->asym_prefer_cpu = max_cpu; + +next: sg = sg->next; } while (sg != sd->groups); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c242944..af97dc8 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -100,6 +100,17 @@ const_debug unsigned int sysctl_sched_migration_cost = 500000UL; */ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; +#ifdef CONFIG_SMP +/* + * For asym packing, by default the lower numbered cpu has higher priority. + */ +int __weak arch_asym_cpu_priority(int cpu) +{ + return -cpu; +} + +#endif + #ifdef CONFIG_CFS_BANDWIDTH /* * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool @@ -7113,16 +7124,18 @@ static bool update_sd_pick_busiest(struct lb_env *env, if (env->idle == CPU_NOT_IDLE) return true; /* - * ASYM_PACKING needs to move all the work to the lowest - * numbered CPUs in the group, therefore mark all groups - * higher than ourself as busy. + * ASYM_PACKING needs to move all the work to the highest + * prority CPUs in the group, therefore mark all groups + * of lower priority than ourself as busy. */ - if (sgs->sum_nr_running && env->dst_cpu < group_first_cpu(sg)) { + if (sgs->sum_nr_running && + sched_asym_prefer(env->dst_cpu, sg->asym_prefer_cpu)) { if (!sds->busiest) return true; - /* Prefer to move from highest possible cpu's work */ - if (group_first_cpu(sds->busiest) < group_first_cpu(sg)) + /* Prefer to move from lowest priority cpu's work */ + if (sched_asym_prefer(sds->busiest->asym_prefer_cpu, + sg->asym_prefer_cpu)) return true; } @@ -7274,8 +7287,8 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) if (!sds->busiest) return 0; - busiest_cpu = group_first_cpu(sds->busiest); - if (env->dst_cpu > busiest_cpu) + busiest_cpu = sds->busiest->asym_prefer_cpu; + if (sched_asym_prefer(busiest_cpu, env->dst_cpu)) return 0; env->imbalance = DIV_ROUND_CLOSEST( @@ -7613,10 +7626,11 @@ static int need_active_balance(struct lb_env *env) /* * ASYM_PACKING needs to force migrate tasks from busy but - * higher numbered CPUs in order to pack all tasks in the - * lowest numbered CPUs. + * lower priority CPUs in order to pack all tasks in the + * highest priority CPUs. */ - if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) + if ((sd->flags & SD_ASYM_PACKING) && + sched_asym_prefer(env->dst_cpu, env->src_cpu)) return 1; } @@ -8465,7 +8479,7 @@ static inline bool nohz_kick_needed(struct rq *rq) unsigned long now = jiffies; struct sched_domain_shared *sds; struct sched_domain *sd; - int nr_busy, cpu = rq->cpu; + int nr_busy, i, cpu = rq->cpu; bool kick = false; if (unlikely(rq->idle_balance)) @@ -8516,12 +8530,18 @@ static inline bool nohz_kick_needed(struct rq *rq) } sd = rcu_dereference(per_cpu(sd_asym, cpu)); - if (sd && (cpumask_first_and(nohz.idle_cpus_mask, - sched_domain_span(sd)) < cpu)) { - kick = true; - goto unlock; - } + if (sd) { + for_each_cpu(i, sched_domain_span(sd)) { + if (i == cpu || + !cpumask_test_cpu(i, nohz.idle_cpus_mask)) + continue; + if (sched_asym_prefer(i, cpu)) { + kick = true; + goto unlock; + } + } + } unlock: rcu_read_unlock(); return kick; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 055f935..cd3d413 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -539,6 +539,11 @@ struct dl_rq { #ifdef CONFIG_SMP +static inline bool sched_asym_prefer(int a, int b) +{ + return arch_asym_cpu_priority(a) > arch_asym_cpu_priority(b); +} + /* * We add the notion of a root-domain which will be used to define per-domain * variables. Each exclusive cpuset essentially defines an island domain by @@ -905,6 +910,7 @@ struct sched_group { unsigned int group_weight; struct sched_group_capacity *sgc; + int asym_prefer_cpu; /* cpu of highest priority in group */ /* * The CPUs this group covers. -- 2.5.5