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authorNick Piggin <nickpiggin@yahoo.com.au>2005-06-25 14:57:13 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-25 16:24:41 -0700
commit7897986bad8f6cd50d6149345aca7f6480f49464 (patch)
tree10a5e08e004ae685aaab6823a3774803455b7704 /kernel
parent99b61ccf0bf0e9a85823d39a5db6a1519caeb13d (diff)
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[PATCH] sched: balance timers
Do CPU load averaging over a number of different intervals. Allow each interval to be chosen by sending a parameter to source_load and target_load. 0 is instantaneous, idx > 0 returns a decaying average with the most recent sample weighted at 2^(idx-1). To a maximum of 3 (could be easily increased). So generally a higher number will result in more conservative balancing. Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c138
1 files changed, 74 insertions, 64 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index f665de34ed8..b597b07e791 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -206,7 +206,7 @@ struct runqueue {
*/
unsigned long nr_running;
#ifdef CONFIG_SMP
- unsigned long cpu_load;
+ unsigned long cpu_load[3];
#endif
unsigned long long nr_switches;
@@ -886,23 +886,27 @@ void kick_process(task_t *p)
* We want to under-estimate the load of migration sources, to
* balance conservatively.
*/
-static inline unsigned long source_load(int cpu)
+static inline unsigned long source_load(int cpu, int type)
{
runqueue_t *rq = cpu_rq(cpu);
unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+ if (type == 0)
+ return load_now;
- return min(rq->cpu_load, load_now);
+ return min(rq->cpu_load[type-1], load_now);
}
/*
* Return a high guess at the load of a migration-target cpu
*/
-static inline unsigned long target_load(int cpu)
+static inline unsigned long target_load(int cpu, int type)
{
runqueue_t *rq = cpu_rq(cpu);
unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+ if (type == 0)
+ return load_now;
- return max(rq->cpu_load, load_now);
+ return max(rq->cpu_load[type-1], load_now);
}
#endif
@@ -967,7 +971,7 @@ static int try_to_wake_up(task_t * p, unsigned int state, int sync)
runqueue_t *rq;
#ifdef CONFIG_SMP
unsigned long load, this_load;
- struct sched_domain *sd;
+ struct sched_domain *sd, *this_sd = NULL;
int new_cpu;
#endif
@@ -986,72 +990,64 @@ static int try_to_wake_up(task_t * p, unsigned int state, int sync)
if (unlikely(task_running(rq, p)))
goto out_activate;
-#ifdef CONFIG_SCHEDSTATS
+ new_cpu = cpu;
+
schedstat_inc(rq, ttwu_cnt);
if (cpu == this_cpu) {
schedstat_inc(rq, ttwu_local);
- } else {
- for_each_domain(this_cpu, sd) {
- if (cpu_isset(cpu, sd->span)) {
- schedstat_inc(sd, ttwu_wake_remote);
- break;
- }
+ goto out_set_cpu;
+ }
+
+ for_each_domain(this_cpu, sd) {
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_wake_remote);
+ this_sd = sd;
+ break;
}
}
-#endif
- new_cpu = cpu;
- if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
+ if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
goto out_set_cpu;
- load = source_load(cpu);
- this_load = target_load(this_cpu);
-
/*
- * If sync wakeup then subtract the (maximum possible) effect of
- * the currently running task from the load of the current CPU:
+ * Check for affine wakeup and passive balancing possibilities.
*/
- if (sync)
- this_load -= SCHED_LOAD_SCALE;
-
- /* 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)
- goto out_set_cpu;
+ if (this_sd) {
+ int idx = this_sd->wake_idx;
+ unsigned int imbalance;
- new_cpu = this_cpu; /* Wake to this CPU if we can */
+ load = source_load(cpu, idx);
+ this_load = target_load(this_cpu, idx);
- /*
- * Scan domains for affine wakeup and passive balancing
- * possibilities.
- */
- for_each_domain(this_cpu, sd) {
- unsigned int imbalance;
/*
- * Start passive balancing when half the imbalance_pct
- * limit is reached.
+ * If sync wakeup then subtract the (maximum possible) effect of
+ * the currently running task from the load of the current CPU:
*/
- imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2;
+ if (sync)
+ this_load -= SCHED_LOAD_SCALE;
+
+ /* 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)
+ goto out_set_cpu;
- if ((sd->flags & SD_WAKE_AFFINE) &&
- !task_hot(p, rq->timestamp_last_tick, sd)) {
+ new_cpu = this_cpu; /* Wake to this CPU if we can */
+
+ if ((this_sd->flags & SD_WAKE_AFFINE) &&
+ !task_hot(p, rq->timestamp_last_tick, this_sd)) {
/*
* This domain has SD_WAKE_AFFINE and p is cache cold
* in this domain.
*/
- if (cpu_isset(cpu, sd->span)) {
- schedstat_inc(sd, ttwu_move_affine);
- goto out_set_cpu;
- }
- } else if ((sd->flags & SD_WAKE_BALANCE) &&
+ schedstat_inc(this_sd, ttwu_move_affine);
+ goto out_set_cpu;
+ } else if ((this_sd->flags & SD_WAKE_BALANCE) &&
imbalance*this_load <= 100*load) {
/*
* This domain has SD_WAKE_BALANCE and there is
* an imbalance.
*/
- if (cpu_isset(cpu, sd->span)) {
- schedstat_inc(sd, ttwu_move_balance);
- goto out_set_cpu;
- }
+ schedstat_inc(this_sd, ttwu_move_balance);
+ goto out_set_cpu;
}
}
@@ -1509,7 +1505,7 @@ static int find_idlest_cpu(struct task_struct *p, int this_cpu,
cpus_and(mask, sd->span, p->cpus_allowed);
for_each_cpu_mask(i, mask) {
- load = target_load(i);
+ load = target_load(i, sd->wake_idx);
if (load < min_load) {
min_cpu = i;
@@ -1522,7 +1518,7 @@ static int find_idlest_cpu(struct task_struct *p, int this_cpu,
}
/* add +1 to account for the new task */
- this_load = source_load(this_cpu) + SCHED_LOAD_SCALE;
+ this_load = source_load(this_cpu, sd->wake_idx) + SCHED_LOAD_SCALE;
/*
* Would with the addition of the new task to the
@@ -1767,8 +1763,15 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
{
struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
unsigned long max_load, avg_load, total_load, this_load, total_pwr;
+ int load_idx;
max_load = this_load = total_load = total_pwr = 0;
+ if (idle == NOT_IDLE)
+ load_idx = sd->busy_idx;
+ else if (idle == NEWLY_IDLE)
+ load_idx = sd->newidle_idx;
+ else
+ load_idx = sd->idle_idx;
do {
unsigned long load;
@@ -1783,9 +1786,9 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
for_each_cpu_mask(i, group->cpumask) {
/* Bias balancing toward cpus of our domain */
if (local_group)
- load = target_load(i);
+ load = target_load(i, load_idx);
else
- load = source_load(i);
+ load = source_load(i, load_idx);
avg_load += load;
}
@@ -1895,7 +1898,7 @@ static runqueue_t *find_busiest_queue(struct sched_group *group)
int i;
for_each_cpu_mask(i, group->cpumask) {
- load = source_load(i);
+ load = source_load(i, 0);
if (load > max_load) {
max_load = load;
@@ -2150,18 +2153,23 @@ static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
unsigned long old_load, this_load;
unsigned long j = jiffies + CPU_OFFSET(this_cpu);
struct sched_domain *sd;
+ int i;
- /* Update our load */
- old_load = this_rq->cpu_load;
this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
- /*
- * Round up the averaging division if load is increasing. This
- * prevents us from getting stuck on 9 if the load is 10, for
- * example.
- */
- if (this_load > old_load)
- old_load++;
- this_rq->cpu_load = (old_load + this_load) / 2;
+ /* Update our load */
+ for (i = 0; i < 3; i++) {
+ unsigned long new_load = this_load;
+ int scale = 1 << i;
+ old_load = this_rq->cpu_load[i];
+ /*
+ * Round up the averaging division if load is increasing. This
+ * prevents us from getting stuck on 9 if the load is 10, for
+ * example.
+ */
+ if (new_load > old_load)
+ new_load += scale-1;
+ this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) / scale;
+ }
for_each_domain(this_cpu, sd) {
unsigned long interval;
@@ -4921,13 +4929,15 @@ void __init sched_init(void)
rq = cpu_rq(i);
spin_lock_init(&rq->lock);
+ rq->nr_running = 0;
rq->active = rq->arrays;
rq->expired = rq->arrays + 1;
rq->best_expired_prio = MAX_PRIO;
#ifdef CONFIG_SMP
rq->sd = &sched_domain_dummy;
- rq->cpu_load = 0;
+ for (j = 1; j < 3; j++)
+ rq->cpu_load[j] = 0;
rq->active_balance = 0;
rq->push_cpu = 0;
rq->migration_thread = NULL;