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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-09-10 14:40:57 +0200
committerIngo Molnar <mingo@elte.hu>2009-09-15 16:01:06 +0200
commitae154be1f34a674e6cbb43ccf6e442f56acd7a70 (patch)
treee1feba2c818216c97e11801ee7a6e3c2592b10af
parentc88d5910890ad35af283344417891344604f0438 (diff)
sched: Weaken SD_POWERSAVINGS_BALANCE
One of the problems of power-saving balancing is that under certain scenarios it is too slow and allows tons of real work to pile up. Avoid this by ignoring the powersave stuff when there's real work to be done. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched.c40
-rw-r--r--kernel/sched_fair.c21
2 files changed, 38 insertions, 23 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 6c819f338b11..f0ccb8b926c8 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1538,6 +1538,26 @@ static unsigned long target_load(int cpu, int type)
return max(rq->cpu_load[type-1], total);
}
+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;
+}
+
static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
static unsigned long cpu_avg_load_per_task(int cpu)
@@ -3982,26 +4002,6 @@ ret:
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.
*/
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 09d19f77eb3a..eaa00014b499 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1333,10 +1333,25 @@ static int select_task_rq_fair(struct task_struct *p, int flag, int sync)
for_each_domain(cpu, tmp) {
/*
- * If power savings logic is enabled for a domain, stop there.
+ * If power savings logic is enabled for a domain, see if we
+ * are not overloaded, if so, don't balance wider.
*/
- if (tmp->flags & SD_POWERSAVINGS_BALANCE)
- break;
+ if (tmp->flags & SD_POWERSAVINGS_BALANCE) {
+ unsigned long power = 0;
+ unsigned long nr_running = 0;
+ unsigned long capacity;
+ int i;
+
+ for_each_cpu(i, sched_domain_span(tmp)) {
+ power += power_of(i);
+ nr_running += cpu_rq(i)->cfs.nr_running;
+ }
+
+ capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
+
+ if (nr_running/2 < capacity)
+ break;
+ }
switch (flag) {
case SD_BALANCE_WAKE: