[PATCH 1/2] sched/deadline: reduce overhead if there are no scheduling parameters changed

[PATCH 1/2] sched/deadline: reduce overhead if there are no scheduling parameters changed

[Wanpeng Li]

There is no need to dequeue/enqueue and push/pull if there are
no scheduling parameters changed for dl class, actually both 
fair and rt class have already check if parameters changed for 
them to avoid unnecessary overhead. This patch add the parameters 
changed verify for dl class in order to reduce overhead.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
 kernel/sched/core.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 603c462..f361867 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3402,6 +3402,21 @@ static bool check_same_owner(struct task_struct *p)
 	return match;
 }
 
+static bool dl_param_changed(struct task_struct *p,
+			const struct sched_attr *attr)
+{
+	struct sched_dl_entity *dl_se = &p->dl;
+
+	if (dl_se->dl_runtime != attr->sched_runtime ||
+		dl_se->dl_deadline != attr->sched_deadline ||
+		dl_se->dl_period != attr->sched_period ||
+		dl_se->flags != attr->sched_flags ||
+		p->rt_priority != attr->sched_priority)
+		return true;
+
+	return false;
+}
+
 static int __sched_setscheduler(struct task_struct *p,
 				const struct sched_attr *attr,
 				bool user)
@@ -3530,7 +3545,7 @@ recheck:
 			goto change;
 		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
 			goto change;
-		if (dl_policy(policy))
+		if (dl_policy(policy) && dl_param_changed(p, attr))
 			goto change;
 
 		p->sched_reset_on_fork = reset_on_fork;
-- 
1.9.1

[PATCH 2/2] sched/deadline: fix pull if dl task who's prio changed is not on queue

[Wanpeng Li]

Dl task who is not on queue and it is also the curr task simultaneously 
can not happen. In addition, pull since the priority of a not on queue 
dl task doesn't make any sense.

This patch fix it by don't pull if dl task who's prio changed is not on 
queue.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
 kernel/sched/deadline.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index b9e44ae..4eaf55c 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1678,7 +1678,10 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
 static void prio_changed_dl(struct rq *rq, struct task_struct *p,
 			    int oldprio)
 {
-	if (task_on_rq_queued(p) || rq->curr == p) {
+	if (!task_on_rq_queued(p))
+		return;
+
+	if (rq->curr == p) {
 #ifdef CONFIG_SMP
 		/*
 		 * This might be too much, but unfortunately
-- 
1.9.1

Re: [PATCH 1/2] sched/deadline: reduce overhead if there are no scheduling parameters changed

[Wanpeng Li]

Sorry to send out a duplicated patchset, please ignore this one.
On 11/19/14, 6:01 PM, Wanpeng Li wrote:
> There is no need to dequeue/enqueue and push/pull if there are
> no scheduling parameters changed for dl class, actually both
> fair and rt class have already check if parameters changed for
> them to avoid unnecessary overhead. This patch add the parameters
> changed verify for dl class in order to reduce overhead.
>
> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
> ---
>   kernel/sched/core.c | 17 ++++++++++++++++-
>   1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 603c462..f361867 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3402,6 +3402,21 @@ static bool check_same_owner(struct task_struct *p)
>   	return match;
>   }
>   
> +static bool dl_param_changed(struct task_struct *p,
> +			const struct sched_attr *attr)
> +{
> +	struct sched_dl_entity *dl_se = &p->dl;
> +
> +	if (dl_se->dl_runtime != attr->sched_runtime ||
> +		dl_se->dl_deadline != attr->sched_deadline ||
> +		dl_se->dl_period != attr->sched_period ||
> +		dl_se->flags != attr->sched_flags ||
> +		p->rt_priority != attr->sched_priority)
> +		return true;
> +
> +	return false;
> +}
> +
>   static int __sched_setscheduler(struct task_struct *p,
>   				const struct sched_attr *attr,
>   				bool user)
> @@ -3530,7 +3545,7 @@ recheck:
>   			goto change;
>   		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
>   			goto change;
> -		if (dl_policy(policy))
> +		if (dl_policy(policy) && dl_param_changed(p, attr))
>   			goto change;
>   
>   		p->sched_reset_on_fork = reset_on_fork;

[PATCH 1/2] sched/deadline: reduce overhead if there are no scheduling parameters changed

[Wanpeng Li]

There is no need to dequeue/enqueue and push/pull if there are
no scheduling parameters changed for dl class, actually both 
fair and rt class have already check if parameters changed for 
them to avoid unnecessary overhead. This patch add the parameters 
changed verify for dl class in order to reduce overhead.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
 kernel/sched/core.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 603c462..f361867 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3402,6 +3402,21 @@ static bool check_same_owner(struct task_struct *p)
 	return match;
 }
 
+static bool dl_param_changed(struct task_struct *p,
+			const struct sched_attr *attr)
+{
+	struct sched_dl_entity *dl_se = &p->dl;
+
+	if (dl_se->dl_runtime != attr->sched_runtime ||
+		dl_se->dl_deadline != attr->sched_deadline ||
+		dl_se->dl_period != attr->sched_period ||
+		dl_se->flags != attr->sched_flags ||
+		p->rt_priority != attr->sched_priority)
+		return true;
+
+	return false;
+}
+
 static int __sched_setscheduler(struct task_struct *p,
 				const struct sched_attr *attr,
 				bool user)
@@ -3530,7 +3545,7 @@ recheck:
 			goto change;
 		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
 			goto change;
-		if (dl_policy(policy))
+		if (dl_policy(policy) && dl_param_changed(p, attr))
 			goto change;
 
 		p->sched_reset_on_fork = reset_on_fork;
-- 
1.9.1

Re: [PATCH 1/2] sched/deadline: reduce overhead if there are no scheduling parameters changed

[Juri Lelli]

Hi,

On 19/11/14 08:35, Wanpeng Li wrote:
> There is no need to dequeue/enqueue and push/pull if there are
> no scheduling parameters changed for dl class, actually both 
> fair and rt class have already check if parameters changed for 
> them to avoid unnecessary overhead. This patch add the parameters 
> changed verify for dl class in order to reduce overhead.
> 
> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
> ---
>  kernel/sched/core.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 603c462..f361867 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3402,6 +3402,21 @@ static bool check_same_owner(struct task_struct *p)
>  	return match;
>  }
>  
> +static bool dl_param_changed(struct task_struct *p,
> +			const struct sched_attr *attr)

Please check alignment.

> +{
> +	struct sched_dl_entity *dl_se = &p->dl;
> +
> +	if (dl_se->dl_runtime != attr->sched_runtime ||
> +		dl_se->dl_deadline != attr->sched_deadline ||
> +		dl_se->dl_period != attr->sched_period ||
> +		dl_se->flags != attr->sched_flags ||
> +		p->rt_priority != attr->sched_priority)

This last one is useless, as we fail above if
attr->sched_priority != 0 when task has !rt_policy.

Thanks,

- Juri

> +		return true;
> +
> +	return false;
> +}
> +
>  static int __sched_setscheduler(struct task_struct *p,
>  				const struct sched_attr *attr,
>  				bool user)
> @@ -3530,7 +3545,7 @@ recheck:
>  			goto change;
>  		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
>  			goto change;
> -		if (dl_policy(policy))
> +		if (dl_policy(policy) && dl_param_changed(p, attr))
>  			goto change;
>  
>  		p->sched_reset_on_fork = reset_on_fork;
>