From 7d9ffa8961482232d964173cccba6e14d2d543b2 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 4 Jul 2013 12:56:46 +0800 Subject: [PATCH] sched: Micro-optimize the smart wake-affine logic Smart wake-affine is using node-size as the factor currently, but the overhead of the mask operation is high. Thus, this patch introduce the 'sd_llc_size' percpu variable, which will record the highest cache-share domain size, and make it to be the new factor, in order to reduce the overhead and make it more reasonable. Tested-by: Davidlohr Bueso Tested-by: Michael Wang Signed-off-by: Peter Zijlstra Acked-by: Michael Wang Cc: Mike Galbraith Link: http://lkml.kernel.org/r/51D5008E.6030102@linux.vnet.ibm.com [ Tidied up the changelog. ] Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 7 ++++++- kernel/sched/fair.c | 2 +- kernel/sched/sched.h | 1 + 3 files changed, 8 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index b7c32cb7bfeb..6df0fbe53767 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5083,18 +5083,23 @@ static void destroy_sched_domains(struct sched_domain *sd, int cpu) * two cpus are in the same cache domain, see cpus_share_cache(). */ DEFINE_PER_CPU(struct sched_domain *, sd_llc); +DEFINE_PER_CPU(int, sd_llc_size); DEFINE_PER_CPU(int, sd_llc_id); static void update_top_cache_domain(int cpu) { struct sched_domain *sd; int id = cpu; + int size = 1; sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); - if (sd) + if (sd) { id = cpumask_first(sched_domain_span(sd)); + size = cpumask_weight(sched_domain_span(sd)); + } rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); + per_cpu(sd_llc_size, cpu) = size; per_cpu(sd_llc_id, cpu) = id; } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 860063a8c849..f237437446e5 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3175,7 +3175,7 @@ static inline unsigned long effective_load(struct task_group *tg, int cpu, static int wake_wide(struct task_struct *p) { - int factor = nr_cpus_node(cpu_to_node(smp_processor_id())); + int factor = this_cpu_read(sd_llc_size); /* * Yeah, it's the switching-frequency, could means many wakee or diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 5e129efb84ce..4c1cb8029feb 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -594,6 +594,7 @@ static inline struct sched_domain *highest_flag_domain(int cpu, int flag) } DECLARE_PER_CPU(struct sched_domain *, sd_llc); +DECLARE_PER_CPU(int, sd_llc_size); DECLARE_PER_CPU(int, sd_llc_id); struct sched_group_power { -- 2.39.2