Jobs submitted in an entity should execute in the order those jobs
are submitted. We make sure that by checking entity->job_queue in
drm_sched_entity_select_rq() so that we don't loadbalance jobs within
an entity.
But because we update entity->job_queue later in drm_sched_entity_push_job(),
there remains a open window when it is possibe that entity->rq might get
updated by drm_sched_entity_select_rq() which should not be allowed.
Changes in this part also improves job distribution.
Below are test results after running amdgpu_test from mesa drm
Before this patch:
sched_name num of many times it got scheduled
========= ==================================
sdma0 314
sdma1 32
comp_1.0.0 56
comp_1.1.0 0
comp_1.1.1 0
comp_1.2.0 0
comp_1.2.1 0
comp_1.3.0 0
comp_1.3.1 0
After this patch:
sched_name num of many times it got scheduled
========= ==================================
sdma1 243
sdma0 164
comp_1.0.1 14
comp_1.1.0 11
comp_1.1.1 10
comp_1.2.0 15
comp_1.2.1 14
comp_1.3.0 10
comp_1.3.1 10
Fixes: 35e160e781a048 (drm/scheduler: change entities rq even earlier)
Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxx>
Reported-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@xxxxxxx>
---
drivers/gpu/drm/scheduler/sched_entity.c | 9 +++++++--
drivers/gpu/drm/scheduler/sched_main.c | 1 +
include/drm/gpu_scheduler.h | 1 +
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 2e3a058fc239..8414e084b6ac 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -67,6 +67,7 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
entity->priority = priority;
entity->sched_list = num_sched_list > 1 ? sched_list : NULL;
entity->last_scheduled = NULL;
+ entity->loadbalance_on = true;
if(num_sched_list)
entity->rq = &sched_list[0]->sched_rq[entity->priority];
@@ -447,6 +448,9 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
entity->last_scheduled = dma_fence_get(&sched_job->s_fence->finished);
spsc_queue_pop(&entity->job_queue);
+ if (!spsc_queue_count(&entity->job_queue))
+ entity->loadbalance_on = true;
+
return sched_job;
}
@@ -463,7 +467,8 @@ 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_sched_list <= 1)
+ atomic_inc(&entity->rq->sched->num_jobs);
+ if ((entity->num_sched_list <= 1) || !entity->loadbalance_on)
return;
fence = READ_ONCE(entity->last_scheduled);
@@ -477,6 +482,7 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
entity->rq = rq;
}
+ entity->loadbalance_on = false;
spin_unlock(&entity->rq_lock);
}
@@ -498,7 +504,6 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
bool first;
trace_drm_sched_job(sched_job, entity);
- atomic_inc(&entity->rq->sched->num_jobs);
WRITE_ONCE(entity->last_user, current->group_leader);
first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 3fad5876a13f..00fdc350134e 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -562,6 +562,7 @@ int drm_sched_job_init(struct drm_sched_job *job,
return -ENOENT;
sched = entity->rq->sched;
+ atomic_inc(&entity->rq->sched->num_jobs);
job->sched = sched;
job->entity = entity;
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index 96a1a1b7526e..a5190869d323 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -97,6 +97,7 @@ struct drm_sched_entity {
struct dma_fence *last_scheduled;
struct task_struct *last_user;
bool stopped;
+ bool loadbalance_on;
struct completion entity_idle;
};
--
2.24.1
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