When the capacity drops low, we want to migrate load away. Allow the
load-balancer to remove all tasks when we hit rock bottom.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
[ego@xxxxxxxxxx: fix to update_sd_power_savings_stats]
Signed-off-by: Dinakar Guniguntala <dino@xxxxxxxxxx>
---
kernel/sched.c | 35 +++++++++++++++++++++++++++++------
1 file changed, 29 insertions(+), 6 deletions(-)
Index: linux-2.6.31.4-rt14/kernel/sched.c
===================================================================
--- linux-2.6.31.4-rt14.orig/kernel/sched.c 2009-10-16 09:15:36.000000000 -0400
+++ linux-2.6.31.4-rt14/kernel/sched.c 2009-10-16 09:15:37.000000000 -0400
@@ -3749,7 +3749,7 @@
* capacity but still has some space to pick up some load
* from other group and save more power
*/
- if (sgs->sum_nr_running > sgs->group_capacity - 1)
+ if (sgs->sum_nr_running + 1 > sgs->group_capacity)
return;
if (sgs->sum_nr_running > sds->leader_nr_running ||
@@ -3989,8 +3989,8 @@
if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
sgs->group_imb = 1;
- sgs->group_capacity = group->__cpu_power / SCHED_LOAD_SCALE;
-
+ sgs->group_capacity =
+ DIV_ROUND_CLOSEST(group->__cpu_power, SCHED_LOAD_SCALE);
}
/**
@@ -4040,7 +4040,7 @@
* and move all the excess tasks away.
*/
if (prefer_sibling)
- sgs.group_capacity = 1;
+ sgs.group_capacity = min(sgs.group_capacity, 1UL);
if (local_group) {
sds->this_load = sgs.avg_load;
@@ -4272,6 +4272,26 @@
return NULL;
}
+static struct sched_group *group_of(int cpu)
+{
+ struct sched_domain *sd = rcu_dereference(cpu_rq(cpu)->sd);
+
+ if (!sd)
+ return NULL;
+
+ return sd->groups;
+}
+
+static unsigned long power_of(int cpu)
+{
+ struct sched_group *group = group_of(cpu);
+
+ if (!group)
+ return SCHED_LOAD_SCALE;
+
+ return group->__cpu_power;
+}
+
/*
* find_busiest_queue - find the busiest runqueue among the cpus in group.
*/
@@ -4284,15 +4304,18 @@
int i;
for_each_cpu(i, sched_group_cpus(group)) {
+ unsigned long power = power_of(i);
+ unsigned long capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
unsigned long wl;
if (!cpumask_test_cpu(i, cpus))
continue;
rq = cpu_rq(i);
- wl = weighted_cpuload(i);
+ wl = weighted_cpuload(i) * SCHED_LOAD_SCALE;
+ wl /= power;
- if (rq->nr_running == 1 && wl > imbalance)
+ if (capacity && rq->nr_running == 1 && wl > imbalance)
continue;
if (wl > max_load) {
--
--
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