Re: sched: add CONFIG_SMP consistency

From: Li Zefan
Date: Wed Oct 22 2008 - 03:25:44 EST


Peter Zijlstra wrote:
> On Tue, 2008-10-21 at 20:45 +0200, henrik@xxxxxxxxx wrote:
>> From: Henrik Austad <henrik.austad@xxxxxxxxx>
>>
>> Do not declare select_task_rq as part of sched_class when CONFIG_SMP is
>> not set.
>

Not only select_task_rq(), but also set_cpus_allowed(), rq_online() and
rq_offline().

> While a proper cleanup, could you do it by re-arranging the methods so
> as to not create an additional ifdef?
>

How about the following patch?

==================


From: Li Zefan <lizf@xxxxxxxxxxxxxx>
Date: Wed, 22 Oct 2008 15:13:06 +0800
Subject: [PATCH] make CONFIG_SMP consistent for sched_class methods

Do not declare select_task_rq and some other methods as part of sched_class
when CONFIG_SMP is not set.

Also gather those methods to avoid CONFIG_SMP mess.

Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
---
include/linux/sched.h | 12 +++++++-----
kernel/sched_fair.c | 5 ++---
kernel/sched_idletask.c | 5 ++---
kernel/sched_rt.c | 5 ++---
4 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5c38db5..fc1a615 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -941,7 +941,6 @@ struct sched_class {
void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup);
void (*dequeue_task) (struct rq *rq, struct task_struct *p, int sleep);
void (*yield_task) (struct rq *rq);
- int (*select_task_rq)(struct task_struct *p, int sync);

void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int sync);

@@ -949,6 +948,8 @@ 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);
+
unsigned long (*load_balance) (struct rq *this_rq, int this_cpu,
struct rq *busiest, unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
@@ -960,16 +961,17 @@ struct sched_class {
void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);
void (*post_schedule) (struct rq *this_rq);
void (*task_wake_up) (struct rq *this_rq, struct task_struct *task);
-#endif

- void (*set_curr_task) (struct rq *rq);
- void (*task_tick) (struct rq *rq, struct task_struct *p, int queued);
- void (*task_new) (struct rq *rq, struct task_struct *p);
void (*set_cpus_allowed)(struct task_struct *p,
const cpumask_t *newmask);

void (*rq_online)(struct rq *rq);
void (*rq_offline)(struct rq *rq);
+#endif
+
+ void (*set_curr_task) (struct rq *rq);
+ void (*task_tick) (struct rq *rq, struct task_struct *p, int queued);
+ void (*task_new) (struct rq *rq, struct task_struct *p);

void (*switched_from) (struct rq *this_rq, struct task_struct *task,
int running);
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index f604dae..73bef78 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1576,9 +1576,6 @@ static const struct sched_class fair_sched_class = {
.enqueue_task = enqueue_task_fair,
.dequeue_task = dequeue_task_fair,
.yield_task = yield_task_fair,
-#ifdef CONFIG_SMP
- .select_task_rq = select_task_rq_fair,
-#endif /* CONFIG_SMP */

.check_preempt_curr = check_preempt_wakeup,

@@ -1586,6 +1583,8 @@ static const struct sched_class fair_sched_class = {
.put_prev_task = put_prev_task_fair,

#ifdef CONFIG_SMP
+ .select_task_rq = select_task_rq_fair,
+
.load_balance = load_balance_fair,
.move_one_task = move_one_task_fair,
#endif
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index dec4cca..8a21a2e 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -105,9 +105,6 @@ static const struct sched_class idle_sched_class = {

/* dequeue is not valid, we print a debug message there: */
.dequeue_task = dequeue_task_idle,
-#ifdef CONFIG_SMP
- .select_task_rq = select_task_rq_idle,
-#endif /* CONFIG_SMP */

.check_preempt_curr = check_preempt_curr_idle,

@@ -115,6 +112,8 @@ static const struct sched_class idle_sched_class = {
.put_prev_task = put_prev_task_idle,

#ifdef CONFIG_SMP
+ .select_task_rq = select_task_rq_idle,
+
.load_balance = load_balance_idle,
.move_one_task = move_one_task_idle,
#endif
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index b446dc8..d9ba9d5 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1504,9 +1504,6 @@ static const struct sched_class rt_sched_class = {
.enqueue_task = enqueue_task_rt,
.dequeue_task = dequeue_task_rt,
.yield_task = yield_task_rt,
-#ifdef CONFIG_SMP
- .select_task_rq = select_task_rq_rt,
-#endif /* CONFIG_SMP */

.check_preempt_curr = check_preempt_curr_rt,

@@ -1514,6 +1511,8 @@ static const struct sched_class rt_sched_class = {
.put_prev_task = put_prev_task_rt,

#ifdef CONFIG_SMP
+ .select_task_rq = select_task_rq_rt,
+
.load_balance = load_balance_rt,
.move_one_task = move_one_task_rt,
.set_cpus_allowed = set_cpus_allowed_rt,
--
1.5.4.rc3


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