[tip:sched/core] sched: Hook sched_balance_self() into sched_class::select_task_rq()

tip-bot for Peter Zijlstra
2009-09-16T10:20:53Z

Commit-ID: 5f3edc1b1ead6d9bd45a85c551f44eff8fe76b9f
Gitweb: http://git.kernel.org/tip/5f3edc1b1ead6d9bd45a85c551f44eff8fe76b9f
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 10 Sep 2009 13:42:00 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 15 Sep 2009 16:01:04 +0200

sched: Hook sched_balance_self() into sched_class::select_task_rq()

Rather ugly patch to fully place the sched_balance_self() code
inside the fair class.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
include/linux/sched.h | 3 ++-
kernel/sched.c | 14 +++++++-------
kernel/sched_fair.c | 7 ++++++-
kernel/sched_idletask.c | 2 +-
kernel/sched_rt.c | 5 ++++-
5 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f3d74bd..5d3c990 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -811,6 +811,7 @@ enum cpu_idle_type {
#define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */
#define SD_WAKE_IDLE_FAR 0x0800 /* Gain latency sacrificing cache hit */
#define SD_PREFER_SIBLING 0x1000 /* Prefer to place tasks in a sibling domain */
+#define SD_BALANCE_WAKE 0x2000 /* Balance on wakeup */

enum powersavings_balance_level {
POWERSAVINGS_BALANCE_NONE = 0, /* No power saving load balance */
@@ -1032,7 +1033,7 @@ struct sched_class {
void (*put_prev_task) (struct rq *rq, struct task_struct *p);

#ifdef CONFIG_SMP
- int (*select_task_rq)(struct task_struct *p, int sync);
+ int (*select_task_rq)(struct task_struct *p, int flag, int sync);

unsigned long (*load_balance) (struct rq *this_rq, int this_cpu,
struct rq *busiest, unsigned long max_load_move,
diff --git a/kernel/sched.c b/kernel/sched.c
index 60400a2..32b7a81 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2350,7 +2350,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
if (unlikely(task_running(rq, p)))
goto out_activate;

- cpu = p->sched_class->select_task_rq(p, sync);
+ cpu = p->sched_class->select_task_rq(p, SD_BALANCE_WAKE, sync);
if (cpu != orig_cpu) {
set_task_cpu(p, cpu);
task_rq_unlock(rq, &flags);
@@ -2525,11 +2525,6 @@ void sched_fork(struct task_struct *p, int clone_flags)

__sched_fork(p);

-#ifdef CONFIG_SMP
- cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
-#endif
- set_task_cpu(p, cpu);
-
/*
* Make sure we do not leak PI boosting priority to the child.
*/
@@ -2560,6 +2555,11 @@ void sched_fork(struct task_struct *p, int clone_flags)
if (!rt_prio(p->prio))
p->sched_class = &fair_sched_class;

+#ifdef CONFIG_SMP
+ cpu = p->sched_class->select_task_rq(p, SD_BALANCE_FORK, 0);
+#endif
+ set_task_cpu(p, cpu);
+
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
if (likely(sched_info_on()))
memset(&p->sched_info, 0, sizeof(p->sched_info));
@@ -3114,7 +3114,7 @@ out:
void sched_exec(void)
{
int new_cpu, this_cpu = get_cpu();
- new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
+ new_cpu = current->sched_class->select_task_rq(current, SD_BALANCE_EXEC, 0);
put_cpu();
if (new_cpu != this_cpu)
sched_migrate_task(current, new_cpu);
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index a82d71d..f2eb5b9 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1300,7 +1300,9 @@ wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
return 0;
}

-static int select_task_rq_fair(struct task_struct *p, int sync)
+static int sched_balance_self(int cpu, int flag);
+
+static int select_task_rq_fair(struct task_struct *p, int flag, int sync)
{
struct sched_domain *sd, *this_sd = NULL;
int prev_cpu, this_cpu, new_cpu;
@@ -1314,6 +1316,9 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
this_rq = cpu_rq(this_cpu);
new_cpu = prev_cpu;

+ if (flag != SD_BALANCE_WAKE)
+ return sched_balance_self(this_cpu, flag);
+
/*
* 'this_sd' is the first domain that both
* this_cpu and prev_cpu are present in:
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 499672c..99b2f03 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -6,7 +6,7 @@
*/

#ifdef CONFIG_SMP
-static int select_task_rq_idle(struct task_struct *p, int sync)
+static int select_task_rq_idle(struct task_struct *p, int flag, int sync)
{
return task_cpu(p); /* IDLE tasks as never migrated */
}
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 2eb4bd6..4383808 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -938,10 +938,13 @@ static void yield_task_rt(struct rq *rq)
#ifdef CONFIG_SMP
static int find_lowest_rq(struct task_struct *task);

-static int select_task_rq_rt(struct task_struct *p, int sync)
+static int select_task_rq_rt(struct task_struct *p, int flag, int sync)
{
struct rq *rq = task_rq(p);

+ if (flag != SD_BALANCE_WAKE)
+ return smp_processor_id();
+
/*
* If the current task is an RT task, then
* try to see if we can wake this RT task up on another