[RFC PATCH] drm/amdgpu: allocate entities on demand

Nirmoy nirmodas at amd.com
Tue Dec 3 15:02:17 UTC 2019 

Hi Christian,

On 12/2/19 3:59 PM, Christian König wrote:
> Am 02.12.19 um 15:43 schrieb Nirmoy:
>>
>> Do you mean something like
>>
>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>> index 684692a8ed76..ac67f8f098fa 100644
>> --- a/include/drm/gpu_scheduler.h
>> +++ b/include/drm/gpu_scheduler.h
>> @@ -81,7 +81,7 @@ enum drm_sched_priority {
>>  struct drm_sched_entity {
>>         struct list_head                list;
>>         struct drm_sched_rq             *rq;
>> -       struct drm_sched_rq             **rq_list;
>> +      struct drm_gpu_scheduler        **sched;
>>         unsigned int                    num_rq_list;
>>         spinlock_t                      rq_lock;
>
> Yes, exactly. Problem is that I'm not 100% sure if that really works 
> with all users of the rq_list.

currently rq_list users does two main tasks.

1  change rq priority for a context on user requests

2  helps drm scheduler to find rq  with least load.

Can you please check the bellow diff it doesn't really work because I 
get some kernel panic. But do you think

it is matching your idea ?

test at install:~/linux> git diff drivers/gpu/drm/scheduler/sched_entity.c 
|tee
diff --git a/drivers/gpu/drm/scheduler/sched_entity.c 
b/drivers/gpu/drm/scheduler/sched_entity.c
index 1a5153197fe9..0bbd8ddd6c83 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -37,9 +37,9 @@
   * submit to HW ring.
   *
   * @entity: scheduler entity to init
- * @rq_list: the list of run queue on which jobs from this
+ * @sched_list: the list of drm scheds on which jobs from this
   *           entity can be submitted
- * @num_rq_list: number of run queue in rq_list
+ * @num_sched_list: number of drm sched in sched_list
   * @guilty: atomic_t set to 1 when a job on this queue
   *          is found to be guilty causing a timeout
   *
@@ -49,30 +49,24 @@
   * Returns 0 on success or a negative error code on failure.
   */
  int drm_sched_entity_init(struct drm_sched_entity *entity,
-              struct drm_sched_rq **rq_list,
-              unsigned int num_rq_list,
-              atomic_t *guilty)
+              struct drm_gpu_scheduler **sched_list,
+              unsigned int num_sched_list,
+              atomic_t *guilty, enum drm_sched_priority priority)
  {
-    int i;

-    if (!(entity && rq_list && (num_rq_list == 0 || rq_list[0])))
+    if (!(entity && sched_list && (num_sched_list == 0 || sched_list[0])))
          return -EINVAL;

      memset(entity, 0, sizeof(struct drm_sched_entity));
      INIT_LIST_HEAD(&entity->list);
      entity->rq = NULL;
      entity->guilty = guilty;
-    entity->num_rq_list = num_rq_list;
-    entity->rq_list = kcalloc(num_rq_list, sizeof(struct drm_sched_rq *),
-                GFP_KERNEL);
-    if (!entity->rq_list)
-        return -ENOMEM;
-
-    for (i = 0; i < num_rq_list; ++i)
-        entity->rq_list[i] = rq_list[i];
+    entity->num_sched_list = num_sched_list;
+    entity->sched_list =  sched_list
+    entity->priority = priority;

-    if (num_rq_list)
-        entity->rq = rq_list[0];
+    if (num_sched_list)
+        entity->rq = &entity->sched_list[0]->sched_rq[entity->priority];

      entity->last_scheduled = NULL;

@@ -136,10 +130,10 @@ drm_sched_entity_get_free_sched(struct 
drm_sched_entity *entity)
      unsigned int min_jobs = UINT_MAX, num_jobs;
      int i;

-    for (i = 0; i < entity->num_rq_list; ++i) {
-        struct drm_gpu_scheduler *sched = entity->rq_list[i]->sched;
+    for (i = 0; i < entity->num_sched_list; ++i) {
+        struct drm_gpu_scheduler *sched = entity->sched_list[i];

-        if (!entity->rq_list[i]->sched->ready) {
+        if (!entity->sched_list[i]->ready) {
              DRM_WARN("sched%s is not ready, skipping", sched->name);
              continue;
          }
@@ -147,7 +141,7 @@ drm_sched_entity_get_free_sched(struct 
drm_sched_entity *entity)
          num_jobs = atomic_read(&sched->num_jobs);
          if (num_jobs < min_jobs) {
              min_jobs = num_jobs;
-            rq = entity->rq_list[i];
+            rq = &entity->sched_list[i]->sched_rq[entity->priority];
          }
      }

@@ -304,7 +298,6 @@ void drm_sched_entity_fini(struct drm_sched_entity 
*entity)

      dma_fence_put(entity->last_scheduled);
      entity->last_scheduled = NULL;
-    kfree(entity->rq_list);
  }
  EXPORT_SYMBOL(drm_sched_entity_fini);

@@ -372,8 +365,9 @@ void drm_sched_entity_set_priority(struct 
drm_sched_entity *entity,
      unsigned int i;

      spin_lock(&entity->rq_lock);
-
-    for (i = 0; i < entity->num_rq_list; ++i)
+//TODO
+/*
+    for (i = 0; i < entity->num_sched_list; ++i)
  drm_sched_entity_set_rq_priority(&entity->rq_list[i], priority);

      if (entity->rq) {
@@ -381,7 +375,7 @@ void drm_sched_entity_set_priority(struct 
drm_sched_entity *entity,
          drm_sched_entity_set_rq_priority(&entity->rq, priority);
          drm_sched_rq_add_entity(entity->rq, entity);
      }
-
+*/
      spin_unlock(&entity->rq_lock);
  }
  EXPORT_SYMBOL(drm_sched_entity_set_priority);
@@ -486,7 +480,7 @@ void drm_sched_entity_select_rq(struct 
drm_sched_entity *entity)
      struct dma_fence *fence;
      struct drm_sched_rq *rq;

-    if (spsc_queue_count(&entity->job_queue) || entity->num_rq_list <= 1)
+    if (spsc_queue_count(&entity->job_queue) || entity->num_sched_list 
<= 1)
          return;

      fence = READ_ONCE(entity->last_scheduled);

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