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authorPreeti U Murthy <preeti@linux.vnet.ibm.com>2013-10-30 08:42:52 +0530
committerIngo Molnar <mingo@kernel.org>2013-11-06 12:37:55 +0100
commit37dc6b50cee97954c4e6edcd5b1fa614b76038ee (patch)
treef317a2532d134b113c088bdf5026fb4aef1423c4 /kernel/sched/core.c
parent2042abe7977222ef606306faa2dce8fd51e98e65 (diff)
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sched: Remove unnecessary iteration over sched domains to update nr_busy_cpus
nr_busy_cpus parameter is used by nohz_kick_needed() to find out the number of busy cpus in a sched domain which has SD_SHARE_PKG_RESOURCES flag set. Therefore instead of updating nr_busy_cpus at every level of sched domain, since it is irrelevant, we can update this parameter only at the parent domain of the sd which has this flag set. Introduce a per-cpu parameter sd_busy which represents this parent domain. In nohz_kick_needed() we directly query the nr_busy_cpus parameter associated with the groups of sd_busy. By associating sd_busy with the highest domain which has SD_SHARE_PKG_RESOURCES flag set, we cover all lower level domains which could have this flag set and trigger nohz_idle_balancing if any of the levels have more than one busy cpu. sd_busy is irrelevant for asymmetric load balancing. However sd_asym has been introduced to represent the highest sched domain which has SD_ASYM_PACKING flag set so that it can be queried directly when required. While we are at it, we might as well change the nohz_idle parameter to be updated at the sd_busy domain level alone and not the base domain level of a CPU. This will unify the concept of busy cpus at just one level of sched domain where it is currently used. Signed-off-by: Preeti U Murthy<preeti@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: svaidy@linux.vnet.ibm.com Cc: vincent.guittot@linaro.org Cc: bitbucket@online.de Cc: benh@kernel.crashing.org Cc: anton@samba.org Cc: Morten.Rasmussen@arm.com Cc: pjt@google.com Cc: peterz@infradead.org Cc: mikey@neuling.org Link: http://lkml.kernel.org/r/20131030031252.23426.4417.stgit@preeti.in.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/core.c')
-rw-r--r--kernel/sched/core.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index aa066f306be2..1deccd78be98 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4883,6 +4883,8 @@ DEFINE_PER_CPU(struct sched_domain *, sd_llc);
DEFINE_PER_CPU(int, sd_llc_size);
DEFINE_PER_CPU(int, sd_llc_id);
DEFINE_PER_CPU(struct sched_domain *, sd_numa);
+DEFINE_PER_CPU(struct sched_domain *, sd_busy);
+DEFINE_PER_CPU(struct sched_domain *, sd_asym);
static void update_top_cache_domain(int cpu)
{
@@ -4894,6 +4896,7 @@ static void update_top_cache_domain(int cpu)
if (sd) {
id = cpumask_first(sched_domain_span(sd));
size = cpumask_weight(sched_domain_span(sd));
+ rcu_assign_pointer(per_cpu(sd_busy, cpu), sd->parent);
}
rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
@@ -4902,6 +4905,9 @@ static void update_top_cache_domain(int cpu)
sd = lowest_flag_domain(cpu, SD_NUMA);
rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
+
+ sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
+ rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
}
/*
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