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From 9f25d18f45a8391488feb9783404f2f79b7090f4 Mon Sep 17 00:00:00 2001
From: jplozi <jplozi@unice.fr>
Date: Fri, 11 Mar 2016 15:18:06 +0100
Subject: [PATCH 113/124] overload on wakeup
source https://github.com/jplozi/wastedcores
as an experiment, apply the learnings from the wasted-cores paper
and see how the performance works out. With the data from this we should
be able to work with Peter and the rest of the scheduler folks on
a more permanent/elegant solution.
---
kernel/sched/fair.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c242944f5cbd..5132c828161e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5638,6 +5638,20 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
}
rcu_read_lock();
+
+ if (cpu_rq(prev_cpu)->nr_running) {
+ int _cpu;
+
+ for_each_online_cpu(_cpu) {
+ if (!cpumask_test_cpu(_cpu, tsk_cpus_allowed(p)) ||
+ cpu_rq(_cpu)->nr_running)
+ continue;
+
+ rcu_read_unlock();
+ return _cpu;
+ }
+ }
+
for_each_domain(cpu, tmp) {
if (!(tmp->flags & SD_LOAD_BALANCE))
break;
--
2.11.1
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