From 37dc6b50cee97954c4e6edcd5b1fa614b76038ee Mon Sep 17 00:00:00 2001 From: Preeti U Murthy Date: Wed, 30 Oct 2013 08:42:52 +0530 Subject: 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 Signed-off-by: Peter Zijlstra 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 --- kernel/sched/sched.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/sched/sched.h') diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4e650acffed7..88c85b21d633 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -623,6 +623,8 @@ DECLARE_PER_CPU(struct sched_domain *, sd_llc); DECLARE_PER_CPU(int, sd_llc_size); DECLARE_PER_CPU(int, sd_llc_id); DECLARE_PER_CPU(struct sched_domain *, sd_numa); +DECLARE_PER_CPU(struct sched_domain *, sd_busy); +DECLARE_PER_CPU(struct sched_domain *, sd_asym); struct sched_group_power { atomic_t ref; -- cgit v1.2.3