Re: [PATCH 2/3] drm/scheduler: add counter for total jobs in scheduler

["Zhang, Jerry (Junwei)" <Jerry.Zhang@amd.com>]

On 08/02/2018 02:08 PM, Nayan Deshmukh wrote:
>
>
> On Thu, Aug 2, 2018 at 11:29 AM Zhang, Jerry (Junwei) <Jerry.Zhang@amd.com <mailto:Jerry.Zhang@amd.com>> wrote:
>
>     On 08/02/2018 01:50 PM, Nayan Deshmukh wrote:
>      >
>      >
>      > On Thu, Aug 2, 2018 at 10:31 AM Zhang, Jerry (Junwei) <Jerry.Zhang@amd.com <mailto:Jerry.Zhang@amd.com> <mailto:Jerry.Zhang@amd.com <mailto:Jerry.Zhang@amd.com>>> wrote:
>      >
>      >     On 07/12/2018 02:36 PM, Nayan Deshmukh wrote:
>      >      > Signed-off-by: Nayan Deshmukh <nayan26deshmukh@gmail.com <mailto:nayan26deshmukh@gmail.com> <mailto:nayan26deshmukh@gmail.com <mailto:nayan26deshmukh@gmail.com>>>
>      >      > ---
>      >      >   drivers/gpu/drm/scheduler/gpu_scheduler.c | 3 +++
>      >      >   include/drm/gpu_scheduler.h               | 2 ++
>      >      >   2 files changed, 5 insertions(+)
>      >      >
>      >      > diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>      >      > index 429b1328653a..3dc1a4f07e3f 100644
>      >      > --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
>      >      > +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>      >      > @@ -538,6 +538,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
>      >      >       trace_drm_sched_job(sched_job, entity);
>      >      >
>      >      >       first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
>      >      > +     atomic_inc(&entity->sched->num_jobs);
>      >
>      >     Shall we use hw_rq_count directly or merge them together?
>      >
>      > hw_rq_count is the number of jobs that are currently in the hardware queue as compared to num_jobs which is the number of jobs in the software queue. num_jobs provides a give a better idea of
>     the load
>      > on a scheduler that's why I added that field and used it to decide the scheduler with the least load.
>
>     Thanks for your explanation.
>
>     Then may be more reasonable to move atomic_dec(&sched->num_jobs) after drm_sched_fence_scheduled() or just before atomic_inc(&sched->hw_rq_count).
>     How do you think that?
>
> For now num_jobs also includes jobs that have been pushed to the hardware queue. If I shift it before atomic_inc(&sched->hw_rq_count) then I also need to handle cases when the job was reset and update
> the counter properly. I went for the easier implementation as I felt that num_jobs will correctly represent the load on the scheduler.

Thanks for your info more.
Yes, it's not a simple one deal work, just to clarify it's really meaning, a little overlap with hw_rq_count.
fine for now ;)

>
> But the idea that you suggested can be a potential improvement over what I have done.

Thanks.

Regards,
Jerry
>
> Regards,
> Nayan
>
>     Regards,
>     Jerry
>
>      >
>      > Regards,
>      > Nayan
>      >
>      >
>      >     Regards,
>      >     Jerry
>      >      >
>      >      >       /* first job wakes up scheduler */
>      >      >       if (first) {
>      >      > @@ -818,6 +819,7 @@ static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
>      >      >
>      >      >       dma_fence_get(&s_fence->finished);
>      >      >       atomic_dec(&sched->hw_rq_count);
>      >      > +     atomic_dec(&sched->num_jobs);
>      >      >       drm_sched_fence_finished(s_fence);
>      >      >
>      >      >       trace_drm_sched_process_job(s_fence);
>      >      > @@ -935,6 +937,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
>      >      >       INIT_LIST_HEAD(&sched->ring_mirror_list);
>      >      >       spin_lock_init(&sched->job_list_lock);
>      >      >       atomic_set(&sched->hw_rq_count, 0);
>      >      > +     atomic_set(&sched->num_jobs, 0);
>      >      >       atomic64_set(&sched->job_id_count, 0);
>      >      >
>      >      >       /* Each scheduler will run on a seperate kernel thread */
>      >      > diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>      >      > index 43e93d6077cf..605bd4ad2397 100644
>      >      > --- a/include/drm/gpu_scheduler.h
>      >      > +++ b/include/drm/gpu_scheduler.h
>      >      > @@ -257,6 +257,7 @@ struct drm_sched_backend_ops {
>      >      >    * @job_list_lock: lock to protect the ring_mirror_list.
>      >      >    * @hang_limit: once the hangs by a job crosses this limit then it is marked
>      >      >    *              guilty and it will be considered for scheduling further.
>      >      > + * @num_jobs: the number of jobs in queue in the scheduler
>      >      >    *
>      >      >    * One scheduler is implemented for each hardware ring.
>      >      >    */
>      >      > @@ -274,6 +275,7 @@ struct drm_gpu_scheduler {
>      >      >       struct list_head                ring_mirror_list;
>      >      >       spinlock_t                      job_list_lock;
>      >      >       int                             hang_limit;
>      >      > +     atomic_t                        num_jobs;
>      >      >   };
>      >      >
>      >      >   int drm_sched_init(struct drm_gpu_scheduler *sched,
>      >      >
>      >
>
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