[PATCH 2/2] drm/amd/sched: add schuduling policy

[Christian König]

Am 16.03.2017 um 10:00 schrieb Chunming Zhou:
> if high priority rq is full, then process with low priority could be starve.
> Add policy for this problem, the high proiority can ahead of next priority queue,
> the ratio is 2 : 1.
>
> Change-Id: I58f4a6b9cdce8689b18dd8e83dd6e2cf5f99d5fb
> Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>

Well, the idea behind the high priority queues is to actually starve the 
low priority queues to a certain amount.

At least for the kernel queue that is really desired.

Christian.

> ---
>   drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 26 +++++++++++++++++++++++---
>   drivers/gpu/drm/amd/scheduler/gpu_scheduler.h |  2 ++
>   2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> index 0f439dd..4637b6f 100644
> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
> @@ -35,11 +35,16 @@
>   static void amd_sched_process_job(struct fence *f, struct fence_cb *cb);
>   
>   /* Initialize a given run queue struct */
> -static void amd_sched_rq_init(struct amd_sched_rq *rq)
> +static void amd_sched_rq_init(struct amd_gpu_scheduler *sched, enum
> +			      amd_sched_priority pri)
>   {
> +	struct amd_sched_rq *rq = &sched->sched_rq[pri];
> +
>   	spin_lock_init(&rq->lock);
>   	INIT_LIST_HEAD(&rq->entities);
>   	rq->current_entity = NULL;
> +	rq->wait_base = pri * 2;
> +	rq->wait = rq->wait_base;
>   }
>   
>   static void amd_sched_rq_add_entity(struct amd_sched_rq *rq,
> @@ -494,17 +499,32 @@ static void amd_sched_wakeup(struct amd_gpu_scheduler *sched)
>   {
>   	struct amd_sched_entity *entity;
>   	int i;
> +	bool skip;
>   
>   	if (!amd_sched_ready(sched))
>   		return NULL;
>   
> +retry:
> +	skip = false;
>   	/* Kernel run queue has higher priority than normal run queue*/
>   	for (i = AMD_SCHED_PRIORITY_MAX - 1; i >= AMD_SCHED_PRIORITY_MIN; i--) {
> +		if ((i > AMD_SCHED_PRIORITY_MIN) &&
> +		    (sched->sched_rq[i - 1].wait >= sched->sched_rq[i].wait_base)) {
> +			sched->sched_rq[i - 1].wait = sched->sched_rq[i - 1].wait_base;
> +			skip = true;
> +			continue;
> +		}
>   		entity = amd_sched_rq_select_entity(&sched->sched_rq[i]);
> -		if (entity)
> +		if (entity) {
> +			if (i > AMD_SCHED_PRIORITY_MIN)
> +				sched->sched_rq[i - 1].wait++;
>   			break;
> +		}
>   	}
>   
> +	if (!entity && skip)
> +		goto retry;
> +
>   	return entity;
>   }
>   
> @@ -608,7 +628,7 @@ int amd_sched_init(struct amd_gpu_scheduler *sched,
>   	sched->name = name;
>   	sched->timeout = timeout;
>   	for (i = AMD_SCHED_PRIORITY_MIN; i < AMD_SCHED_PRIORITY_MAX; i++)
> -		amd_sched_rq_init(&sched->sched_rq[i]);
> +		amd_sched_rq_init(sched, i);
>   
>   	init_waitqueue_head(&sched->wake_up_worker);
>   	init_waitqueue_head(&sched->job_scheduled);
> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> index 99f0240..4caed30 100644
> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> @@ -64,6 +64,8 @@ struct amd_sched_rq {
>   	spinlock_t		lock;
>   	struct list_head	entities;
>   	struct amd_sched_entity	*current_entity;
> +	int wait_base;
> +	int wait;
>   };
>   
>   struct amd_sched_fence {