[RFC PATCH 13/13] sched: Modifying wake_affine to use PJT's metric

From: Preeti U Murthy
Date: Thu Oct 25 2012 - 06:27:14 EST


Additional parameters introduced to perform this function which are
calculated using PJT's metrics and its helpers.

Signed-off-by: Preeti U Murthy <preeti@xxxxxxxxxxxxxxxxxx>
---
kernel/sched/fair.c | 34 +++++++++++++++-------------------
1 file changed, 15 insertions(+), 19 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 15ec528..b4b572c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2931,19 +2931,6 @@ static unsigned long power_of(int cpu)
return cpu_rq(cpu)->cpu_power;
}

-static unsigned long cpu_avg_load_per_task(int cpu)
-{
- struct rq *rq = cpu_rq(cpu);
- unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
-
- if (nr_running) {
- return rq->load.weight / nr_running;
- }
-
- return 0;
-}
-
-
static void task_waking_fair(struct task_struct *p)
{
struct sched_entity *se = &p->se;
@@ -3085,16 +3072,18 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
{
s64 this_load, load;
int idx, this_cpu, prev_cpu;
- unsigned long tl_per_task;
+ u64 tl_per_task; /* Modified to reflect PJT's metric */
struct task_group *tg;
- unsigned long weight;
+ unsigned long weight, nr_running;
int balanced;

idx = sd->wake_idx;
this_cpu = smp_processor_id();
prev_cpu = task_cpu(p);
- load = source_load(prev_cpu, idx);
- this_load = target_load(this_cpu, idx);
+ /* Both of the below have been modified to use PJT's metric */
+ load = cpu_rq(prev_cpu)->cfs.runnable_load_avg;
+ this_load = cpu_rq(this_cpu)->cfs.runnable_load_avg;
+ nr_running = cpu_rq(this_cpu)->nr_running;

/*
* If sync wakeup then subtract the (maximum possible)
@@ -3104,6 +3093,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
if (sync) {
tg = task_group(current);
weight = current->se.load.weight;
+ weight = current->se.avg.load_avg_contrib;

this_load += effective_load(tg, this_cpu, -weight, -weight);
load += effective_load(tg, prev_cpu, 0, -weight);
@@ -3111,6 +3101,8 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)

tg = task_group(p);
weight = p->se.load.weight;
+ /* The below change to reflect PJT's metric */
+ weight = p->se.avg.load_avg_contrib;

/*
* In low-load situations, where prev_cpu is idle and this_cpu is idle
@@ -3146,11 +3138,15 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
return 1;

schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
- tl_per_task = cpu_avg_load_per_task(this_cpu);
+ /* Below modification to use PJT's metric */
+ if (nr_running)
+ tl_per_task = cpu_rq(this_cpu)->cfs.runnable_load_avg / nr_running;
+ else
+ tl_per_task = 0;

if (balanced ||
(this_load <= load &&
- this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
+ this_load + cpu_rq(prev_cpu)->cfs.runnable_load_avg <= tl_per_task)) {
/*
* This domain has SD_WAKE_AFFINE and
* p is cache cold in this domain, and

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