1 files changed, 57 insertions, 0 deletions

diff --git a/patches/boot_time_opt/0111-overload-on-wakeup.patch b/patches/boot_time_opt/0111-overload-on-wakeup.patch
new file mode 100644
index 0000000..d5125be
--- /dev/null
+++ b/patches/boot_time_opt/0111-overload-on-wakeup.patch
@@ -0,0 +1,57 @@
+From cc7c761946c6b9fa820acc90d7514795af3f42f5 Mon Sep 17 00:00:00 2001
+From: jplozi <jplozi@unice.fr>
+Date: Fri, 11 Mar 2016 15:18:06 +0100
+Subject: [PATCH 111/126] 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(+)
+
+--- linux-4.14/kernel/sched/fair.c.org  2017-11-18 23:01:57.353611850 +0000
++++ linux-4.14/kernel/sched/fair.c      2017-11-19 15:24:38.093637926 +0000
+@@ -5925,6 +5925,8 @@
+        return min_cap * 1024 < task_util(p) * capacity_margin;
+ }
+ 
++
++static unsigned int once_in_a_while;
+ /*
+  * select_task_rq_fair: Select target runqueue for the waking task in domains
+  * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
+@@ -5953,6 +5955,30 @@
+        }
+ 
+        rcu_read_lock();
++       
++       once_in_a_while++;
++
++       if (cpu_rq(prev_cpu)->nr_running || (once_in_a_while & 15) == 0) {
++               int _cpu;
++               int bestprio = -5000;
++               int bestcpu = -1;
++
++               for_each_online_cpu(_cpu) {
++                       if (!cpumask_test_cpu(_cpu, &p->cpus_allowed) ||
++                               cpu_rq(_cpu)->nr_running)
++                               continue;
++                       if (arch_asym_cpu_priority(_cpu) > bestprio || (prev_cpu == _cpu && bestprio == arch_asym_cpu_priority(_cpu))) {
++                               bestcpu = _cpu;
++                               bestprio = arch_asym_cpu_priority(_cpu);
++                       }
++               }
++               
++               if (bestcpu > 0) {
++                       rcu_read_unlock();
++                       return bestcpu;
++               }
++       }
++
+        for_each_domain(cpu, tmp) {
+                if (!(tmp->flags & SD_LOAD_BALANCE))
+                        break;