2020-05-11 19:25:31

by Vincent Guittot

Subject: [PATCH] sched/fair: enqueue_task_fair optimization

enqueue_task_fair() jumps to enqueue_throttle when cfs_rq_of(se) is
throttled, which means that se can't be NULL and we can skip the test.

Signed-off-by: Vincent Guittot <[email protected]>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4b73518aa25c..910bbbe50365 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5512,7 +5512,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
list_add_leaf_cfs_rq(cfs_rq);
}

-enqueue_throttle:
if (!se) {
add_nr_running(rq, 1);
/*
@@ -5534,6 +5533,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)

}

+enqueue_throttle:
if (cfs_bandwidth_used()) {
/*
* When bandwidth control is enabled; the cfs_rq_throttled()
--
2.17.1

2020-05-12 10:22:46

by Pavankumar Kondeti

Subject: Re: [PATCH] sched/fair: enqueue_task_fair optimization

On Mon, May 11, 2020 at 09:23:01PM +0200, Vincent Guittot wrote:
> enqueue_task_fair() jumps to enqueue_throttle when cfs_rq_of(se) is
> throttled, which means that se can't be NULL and we can skip the test.
>
> Signed-off-by: Vincent Guittot <[email protected]>
> ---
> kernel/sched/fair.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 4b73518aa25c..910bbbe50365 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5512,7 +5512,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
> list_add_leaf_cfs_rq(cfs_rq);
> }
>
> -enqueue_throttle:
> if (!se) {
> add_nr_running(rq, 1);
> /*
> @@ -5534,6 +5533,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
>
> }
>
> +enqueue_throttle:
> if (cfs_bandwidth_used()) {
> /*
> * When bandwidth control is enabled; the cfs_rq_throttled()

Right, se can't be NULL when we break upon throttling. Looks good to me.

Thanks,
Pavan

--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

2020-05-12 15:59:57

by Phil Auld

Subject: Re: [PATCH] sched/fair: enqueue_task_fair optimization

On Mon, May 11, 2020 at 09:23:01PM +0200 Vincent Guittot wrote:
> enqueue_task_fair() jumps to enqueue_throttle when cfs_rq_of(se) is
> throttled, which means that se can't be NULL and we can skip the test.
>
> Signed-off-by: Vincent Guittot <[email protected]>
> ---
> kernel/sched/fair.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 4b73518aa25c..910bbbe50365 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5512,7 +5512,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
> list_add_leaf_cfs_rq(cfs_rq);
> }
>
> -enqueue_throttle:
> if (!se) {
> add_nr_running(rq, 1);
> /*
> @@ -5534,6 +5533,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
>
> }
>
> +enqueue_throttle:
> if (cfs_bandwidth_used()) {
> /*
> * When bandwidth control is enabled; the cfs_rq_throttled()
> --
> 2.17.1
>


Reviewed-by: Phil Auld <[email protected]>

--