From: Ingo Molnar <mingo@elte.hu>
This does the source/target cleanup. This is a no-functionality patch which
also adds more comments to explain these functions.
---
25-akpm/kernel/sched.c | 26 ++++++++++++++++----------
1 files changed, 16 insertions(+), 10 deletions(-)
diff -puN kernel/sched.c~sched-cpu-load-cleanup kernel/sched.c
--- 25/kernel/sched.c~sched-cpu-load-cleanup Mon Apr 26 15:31:44 2004
+++ 25-akpm/kernel/sched.c Mon Apr 26 15:31:44 2004
@@ -645,9 +645,12 @@ void kick_process(task_t *p)
EXPORT_SYMBOL_GPL(kick_process);
/*
- * Return a low guess at the load of cpu.
+ * Return a low guess at the load of a migration-source cpu.
+ *
+ * We want to under-estimate the load of migration sources, to
+ * balance conservatively.
*/
-static inline unsigned long get_low_cpu_load(int cpu)
+static inline unsigned long source_load(int cpu)
{
runqueue_t *rq = cpu_rq(cpu);
unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
@@ -655,7 +658,10 @@ static inline unsigned long get_low_cpu_
return min(rq->cpu_load, load_now);
}
-static inline unsigned long get_high_cpu_load(int cpu)
+/*
+ * Return a high guess at the load of a migration-target cpu
+ */
+static inline unsigned long target_load(int cpu)
{
runqueue_t *rq = cpu_rq(cpu);
unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
@@ -751,8 +757,8 @@ static int try_to_wake_up(task_t * p, un
if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
goto out_set_cpu;
- load = get_low_cpu_load(cpu);
- this_load = get_high_cpu_load(this_cpu);
+ load = source_load(cpu);
+ this_load = target_load(this_cpu);
/* Don't pull the task off an idle CPU to a busy one */
if (load < SCHED_LOAD_SCALE/2 && this_load > SCHED_LOAD_SCALE/2)
@@ -1207,9 +1213,9 @@ static int sched_best_cpu(struct task_st
for_each_cpu_mask(i, tmp) {
unsigned long load;
if (i == this_cpu)
- load = get_low_cpu_load(i);
+ load = source_load(i);
else
- load = get_high_cpu_load(i) + SCHED_LOAD_SCALE;
+ load = target_load(i) + SCHED_LOAD_SCALE;
if (min_load > load) {
best_cpu = i;
@@ -1426,9 +1432,9 @@ find_busiest_group(struct sched_domain *
for_each_cpu_mask(i, tmp) {
/* Bias balancing toward cpus of our domain */
if (local_group)
- load = get_high_cpu_load(i);
+ load = target_load(i);
else
- load = get_low_cpu_load(i);
+ load = source_load(i);
nr_cpus++;
avg_load += load;
@@ -1548,7 +1554,7 @@ static runqueue_t *find_busiest_queue(st
cpus_and(tmp, group->cpumask, cpu_online_map);
for_each_cpu_mask(i, tmp) {
- load = get_low_cpu_load(i);
+ load = source_load(i);
if (load > max_load) {
max_load = load;
_