[tip:sched/core] sched: Rate-limit newidle

tip-bot for Mike Galbraith
2009-11-04T19:34:17Z

Commit-ID: 1b9508f6831e10d53256825de8904caa22d1ca2c
Gitweb: http://git.kernel.org/tip/1b9508f6831e10d53256825de8904caa22d1ca2c
Author: Mike Galbraith <efault@gmx.de>
AuthorDate: Wed, 4 Nov 2009 17:53:50 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 4 Nov 2009 19:13:48 +0100

sched: Rate-limit newidle

Rate limit newidle to migration_cost. It's a win for all
stages of sysbench oltp tests.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched.c | 22 +++++++++++++++++++++-
kernel/sched_debug.c | 4 ++++
2 files changed, 25 insertions(+), 1 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index ae026aa..f849212 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -589,6 +589,8 @@ struct rq {

u64 rt_avg;
u64 age_stamp;
+ u64 idle_stamp;
+ u64 avg_idle;
#endif

/* calc_load related fields */
@@ -2353,6 +2355,17 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
if (rq != orig_rq)
update_rq_clock(rq);

+ if (rq->idle_stamp) {
+ u64 delta = rq->clock - rq->idle_stamp;
+ u64 max = 2*sysctl_sched_migration_cost;
+
+ if (delta > max)
+ rq->avg_idle = max;
+ else
+ update_avg(&rq->avg_idle, delta);
+ rq->idle_stamp = 0;
+ }
+
WARN_ON(p->state != TASK_WAKING);
cpu = task_cpu(p);

@@ -4389,6 +4402,11 @@ static void idle_balance(int this_cpu, struct rq *this_rq)
int pulled_task = 0;
unsigned long next_balance = jiffies + HZ;

+ this_rq->idle_stamp = this_rq->clock;
+
+ if (this_rq->avg_idle < sysctl_sched_migration_cost)
+ return;
+
for_each_domain(this_cpu, sd) {
unsigned long interval;

@@ -4403,8 +4421,10 @@ static void idle_balance(int this_cpu, struct rq *this_rq)
interval = msecs_to_jiffies(sd->balance_interval);
if (time_after(next_balance, sd->last_balance + interval))
next_balance = sd->last_balance + interval;
- if (pulled_task)
+ if (pulled_task) {
+ this_rq->idle_stamp = 0;
break;
+ }
}
if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
/*
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index efb8440..6988cf0 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -285,12 +285,16 @@ static void print_cpu(struct seq_file *m, int cpu)

#ifdef CONFIG_SCHEDSTATS
#define P(n) SEQ_printf(m, " .%-30s: %d\n", #n, rq->n);
+#define P64(n) SEQ_printf(m, " .%-30s: %Ld\n", #n, rq->n);

P(yld_count);

P(sched_switch);
P(sched_count);
P(sched_goidle);
+#ifdef CONFIG_SMP
+ P64(avg_idle);
+#endif

P(ttwu_count);
P(ttwu_local);