Am 31.07.2018 um 12:37 schrieb Nayan Deshmukh:
> The function selects the run queue from the rq_list with the
> least load. The load is decided by the number of jobs in a
> scheduler.
>
> Signed-off-by: Nayan Deshmukh <nayan26deshmukh at gmail.com>
> ---
> drivers/gpu/drm/scheduler/gpu_scheduler.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> index 375f6f7f6a93..c67f65ad8f15 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> @@ -255,6 +255,32 @@ static bool drm_sched_entity_is_ready(struct drm_sched_entity *entity)
> return true;
> }
>
> +/**
> + * drm_sched_entity_get_free_sched - Get the rq from rq_list with least load
> + *
> + * @entity: scheduler entity
> + *
> + * Return the pointer to the rq with least load.
> + */
> +static struct drm_sched_rq *
> +drm_sched_entity_get_free_sched(struct drm_sched_entity *entity)
> +{
> + struct drm_sched_rq *rq = NULL;
> + unsigned int min_jobs = UINT_MAX;
> + int i;
> +
> + for (i = 0; i < entity->num_rq_list; ++i) {
> + if (atomic_read(&entity->rq_list[i]->sched->num_jobs) <
> + min_jobs) {
> + min_jobs = atomic_read(
> + &entity->rq_list[i]->sched->num_jobs);
When you use atomic_read twice you might get different results because
the atomic has changed in the meantime.
In other words you need to store the result locally:
unsigned int num_jobs = atomic_read(....);
if (num_jobs < min_jobs) {
   min_jobs = num_jobs;
   .....
Christian.
> + rq = entity->rq_list[i];
> + }
> + }
> +
> + return rq;
> +}
> +
> static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
> struct dma_fence_cb *cb)
> {
