Re: [PATCH drm-misc-next v2] drm/sched: implement dynamic job-flow control
From: Luben Tuikov
Date: Wed Oct 11 2023 - 21:52:56 EST
Hi,
Thanks for fixing the title and submitting a v2 of this patch. Comments inlined below.
On 2023-10-09 18:35, Danilo Krummrich wrote:
> Currently, job flow control is implemented simply by limiting the number
> of jobs in flight. Therefore, a scheduler is initialized with a
> submission limit that corresponds to the number of jobs which can be
> sent to the hardware.
>
> This implies that for each job, drivers need to account for the maximum
> job size possible in order to not overflow the ring buffer.
>
> However, there are drivers, such as Nouveau, where the job size has a
> rather large range. For such drivers it can easily happen that job
> submissions not even filling the ring by 1% can block subsequent
> submissions, which, in the worst case, can lead to the ring run dry.
>
> In order to overcome this issue, allow for tracking the actual job size
> instead of the number of jobs. Therefore, add a field to track a job's
> submission credits, which represents the number of credits a job
> contributes to the scheduler's submission limit.
>
> Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
> ---
> Changes in V2:
> ==============
> - fixed up influence on scheduling fairness due to consideration of a job's
> size
> - If we reach a ready entity in drm_sched_select_entity() but can't actually
> queue a job from it due to size limitations, just give up and go to sleep
> until woken up due to a pending job finishing, rather than continue to try
> other entities.
> - added a callback to dynamically update a job's credits (Boris)
> - renamed 'units' to 'credits'
> - fixed commit message and comments as requested by Luben
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 2 +-
> drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c | 2 +-
> drivers/gpu/drm/lima/lima_sched.c | 2 +-
> drivers/gpu/drm/msm/msm_gem_submit.c | 2 +-
> drivers/gpu/drm/nouveau/nouveau_sched.c | 2 +-
> drivers/gpu/drm/panfrost/panfrost_drv.c | 2 +-
> .../gpu/drm/scheduler/gpu_scheduler_trace.h | 2 +-
> drivers/gpu/drm/scheduler/sched_entity.c | 5 +-
> drivers/gpu/drm/scheduler/sched_main.c | 101 +++++++++++++-----
> drivers/gpu/drm/v3d/v3d_gem.c | 2 +-
> include/drm/gpu_scheduler.h | 33 ++++--
> 11 files changed, 115 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> index 78476bc75b4e..d54daaf64bf1 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> @@ -115,7 +115,7 @@ int amdgpu_job_alloc(struct amdgpu_device *adev, struct amdgpu_vm *vm,
> if (!entity)
> return 0;
>
> - return drm_sched_job_init(&(*job)->base, entity, owner);
> + return drm_sched_job_init(&(*job)->base, entity, 1, owner);
> }
>
> int amdgpu_job_alloc_with_ib(struct amdgpu_device *adev,
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> index 45403ea38906..74a446711207 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> @@ -538,7 +538,7 @@ int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
>
> ret = drm_sched_job_init(&submit->sched_job,
> &ctx->sched_entity[args->pipe],
> - submit->ctx);
> + 1, submit->ctx);
> if (ret)
> goto err_submit_put;
>
> diff --git a/drivers/gpu/drm/lima/lima_sched.c b/drivers/gpu/drm/lima/lima_sched.c
> index 50c2075228aa..5dc6678e1eb9 100644
> --- a/drivers/gpu/drm/lima/lima_sched.c
> +++ b/drivers/gpu/drm/lima/lima_sched.c
> @@ -123,7 +123,7 @@ int lima_sched_task_init(struct lima_sched_task *task,
> for (i = 0; i < num_bos; i++)
> drm_gem_object_get(&bos[i]->base.base);
>
> - err = drm_sched_job_init(&task->base, &context->base, vm);
> + err = drm_sched_job_init(&task->base, &context->base, 1, vm);
> if (err) {
> kfree(task->bos);
> return err;
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index 3f1aa4de3b87..6d230c38e4f5 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -48,7 +48,7 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,
> return ERR_PTR(ret);
> }
>
> - ret = drm_sched_job_init(&submit->base, queue->entity, queue);
> + ret = drm_sched_job_init(&submit->base, queue->entity, 1, queue);
> if (ret) {
> kfree(submit->hw_fence);
> kfree(submit);
> diff --git a/drivers/gpu/drm/nouveau/nouveau_sched.c b/drivers/gpu/drm/nouveau/nouveau_sched.c
> index f26a814a9920..e991426d86e4 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_sched.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_sched.c
> @@ -89,7 +89,7 @@ nouveau_job_init(struct nouveau_job *job,
>
> }
>
> - ret = drm_sched_job_init(&job->base, &entity->base, NULL);
> + ret = drm_sched_job_init(&job->base, &entity->base, 1, NULL);
> if (ret)
> goto err_free_chains;
>
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index b834777b409b..54d1c19bea84 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -274,7 +274,7 @@ static int panfrost_ioctl_submit(struct drm_device *dev, void *data,
>
> ret = drm_sched_job_init(&job->base,
> &file_priv->sched_entity[slot],
> - NULL);
> + 1, NULL);
> if (ret)
> goto out_put_job;
>
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
> index 3143ecaaff86..2e4ffdecc5dc 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
> @@ -51,7 +51,7 @@ DECLARE_EVENT_CLASS(drm_sched_job,
> __assign_str(name, sched_job->sched->name);
> __entry->job_count = spsc_queue_count(&entity->job_queue);
> __entry->hw_job_count = atomic_read(
> - &sched_job->sched->hw_rq_count);
> + &sched_job->sched->submission_count);
> ),
> TP_printk("entity=%p, id=%llu, fence=%p, ring=%s, job count:%u, hw job count:%d",
> __entry->entity, __entry->id,
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index 437c50867c99..6395090d5784 100644
> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> @@ -401,7 +401,8 @@ static void drm_sched_entity_wakeup(struct dma_fence *f,
> container_of(cb, struct drm_sched_entity, cb);
>
> drm_sched_entity_clear_dep(f, cb);
> - drm_sched_wakeup_if_can_queue(drm_sched_entity_to_scheduler(entity));
> + drm_sched_wakeup_if_can_queue(drm_sched_entity_to_scheduler(entity),
> + entity);
> }
>
> /**
> @@ -645,7 +646,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
> if (fifo)
> drm_sched_rq_update_fifo(entity, submit_ts);
>
> - drm_sched_wakeup_if_can_queue(sched);
> + drm_sched_wakeup_if_can_queue(sched, entity);
> }
> }
> EXPORT_SYMBOL(drm_sched_entity_push_job);
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> index 88ef8be2d3c7..da86dd0782d6 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -93,6 +93,9 @@ int drm_sched_policy_default = DRM_SCHED_POLICY_FIFO;
> MODULE_PARM_DESC(sched_policy, "Specify the scheduling policy for entities on a run-queue, " __stringify(DRM_SCHED_POLICY_RR) " = Round Robin, " __stringify(DRM_SCHED_POLICY_FIFO) " = FIFO (default).");
> module_param_named(sched_policy, drm_sched_policy_default, int, 0444);
>
> +static bool drm_sched_can_queue(struct drm_gpu_scheduler *sched,
> + struct drm_sched_entity *entity);
> +
> static __always_inline bool drm_sched_entity_compare_before(struct rb_node *a,
> const struct rb_node *b)
> {
> @@ -212,13 +215,15 @@ void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
> /**
> * drm_sched_rq_select_entity_rr - Select an entity which could provide a job to run
> *
> + * @sched: the gpu scheduler
> * @rq: scheduler run queue to check.
> * @dequeue: dequeue selected entity
> *
> * Try to find a ready entity, returns NULL if none found.
> */
> static struct drm_sched_entity *
> -drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq, bool dequeue)
> +drm_sched_rq_select_entity_rr(struct drm_gpu_scheduler *sched,
> + struct drm_sched_rq *rq, bool dequeue)
> {
> struct drm_sched_entity *entity;
>
> @@ -228,6 +233,12 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq, bool dequeue)
> if (entity) {
> list_for_each_entry_continue(entity, &rq->entities, list) {
> if (drm_sched_entity_is_ready(entity)) {
> + /* If we can't queue yet, preserve the current
> + * entity in terms of fairness.
> + */
> + if (!drm_sched_can_queue(sched, entity))
> + goto out;
> +
> if (dequeue) {
> rq->current_entity = entity;
> reinit_completion(&entity->entity_idle);
> @@ -239,8 +250,13 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq, bool dequeue)
> }
>
> list_for_each_entry(entity, &rq->entities, list) {
> -
> if (drm_sched_entity_is_ready(entity)) {
> + /* If we can't queue yet, preserve the current entity in
> + * terms of fairness.
> + */
> + if (!drm_sched_can_queue(sched, entity))
> + goto out;
> +
> if (dequeue) {
> rq->current_entity = entity;
> reinit_completion(&entity->entity_idle);
> @@ -253,21 +269,23 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq, bool dequeue)
> break;
> }
>
> +out:
> spin_unlock(&rq->lock);
> -
> return NULL;
> }
>
> /**
> * drm_sched_rq_select_entity_fifo - Select an entity which provides a job to run
> *
> + * @sched: the gpu scheduler
> * @rq: scheduler run queue to check.
> * @dequeue: dequeue selected entity
> *
> * Find oldest waiting ready entity, returns NULL if none found.
> */
> static struct drm_sched_entity *
> -drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq, bool dequeue)
> +drm_sched_rq_select_entity_fifo(struct drm_gpu_scheduler *sched,
> + struct drm_sched_rq *rq, bool dequeue)
> {
> struct rb_node *rb;
>
> @@ -277,6 +295,15 @@ drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq, bool dequeue)
>
> entity = rb_entry(rb, struct drm_sched_entity, rb_tree_node);
> if (drm_sched_entity_is_ready(entity)) {
> + /* If we can't queue yet, don't pick another entity
> + * which's job might fit and wait until we got space for
> + * this one in terms of fairness.
> + */
> + if (!drm_sched_can_queue(sched, entity)) {
> + spin_unlock(&rq->lock);
> + return NULL;
> + }
> +
I wonder if here it would've been cleaner to just do,
if (!drm_sched_can_queue(sched, entity)) {
rb = NULL;
break;
}
in order to follow the natural flow of the R-B tree search?
In other words, the loop invariant becomes false, we exit the loop,
unlock and return NULL.
Yeah, let's do that.
> if (dequeue) {
> rq->current_entity = entity;
> reinit_completion(&entity->entity_idle);
> @@ -302,13 +329,32 @@ static void drm_sched_run_job_queue(struct drm_gpu_scheduler *sched)
> /**
> * drm_sched_can_queue -- Can we queue more to the hardware?
> * @sched: scheduler instance
> + * @entity: the scheduler entity
> *
> - * Return true if we can push more jobs to the hw, otherwise false.
> + * Return true if we can push at least one more job from @entity, false
> + * otherwise.
> */
> -static bool drm_sched_can_queue(struct drm_gpu_scheduler *sched)
> +static bool drm_sched_can_queue(struct drm_gpu_scheduler *sched,
> + struct drm_sched_entity *entity)
> {
> - return atomic_read(&sched->hw_rq_count) <
> - sched->hw_submission_limit;
> + struct drm_sched_job *s_job;
> +
> + s_job = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
> + if (!s_job)
> + return false;
> +
> + if (sched->ops->update_job_credits) {
> + u32 credits = sched->ops->update_job_credits(s_job);
> +
> + if (credits)
> + s_job->submission_credits = credits;
> + }
> +
> + WARN_ON(s_job->submission_credits > sched->submission_limit);
> +
> + return (sched->submission_limit -
> + atomic_read(&sched->submission_count)) >=
> + s_job->submission_credits;
> }
>
> /**
> @@ -325,12 +371,10 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched, bool dequeue)
> struct drm_sched_entity *entity;
> int i;
>
> - if (!drm_sched_can_queue(sched))
> - return NULL;
> -
> if (sched->single_entity) {
> if (!READ_ONCE(sched->single_entity->stopped) &&
> - drm_sched_entity_is_ready(sched->single_entity))
> + drm_sched_entity_is_ready(sched->single_entity) &&
> + drm_sched_can_queue(sched, sched->single_entity))
> return sched->single_entity;
This mixing of the Xe patches and this patch is very, very annoying.
Here and in RR picking the entity mix-up with "dequeue" which is
now "peek"...
I'd like to have applied this patch to drm-misc-next and inspect it further,
but cannot chase around which version of the Xe patches this patch applies
to, cleanly, so I'd really rather have had this patch on a clean drm-misc-next
tree.
>
> return NULL;
> @@ -339,9 +383,11 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched, bool dequeue)
> /* Kernel run queue has higher priority than normal run queue*/
> for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
> entity = sched->sched_policy == DRM_SCHED_POLICY_FIFO ?
> - drm_sched_rq_select_entity_fifo(&sched->sched_rq[i],
> + drm_sched_rq_select_entity_fifo(sched,
> + &sched->sched_rq[i],
> dequeue) :
> - drm_sched_rq_select_entity_rr(&sched->sched_rq[i],
> + drm_sched_rq_select_entity_rr(sched,
> + &sched->sched_rq[i],
> dequeue);
> if (entity)
> break;
> @@ -399,7 +445,7 @@ static void drm_sched_job_done(struct drm_sched_job *s_job, int result)
> struct drm_sched_fence *s_fence = s_job->s_fence;
> struct drm_gpu_scheduler *sched = s_fence->sched;
>
> - atomic_dec(&sched->hw_rq_count);
> + atomic_sub(s_job->submission_credits, &sched->submission_count);
> atomic_dec(sched->score);
>
> trace_drm_sched_process_job(s_fence);
> @@ -622,7 +668,8 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
> &s_job->cb)) {
> dma_fence_put(s_job->s_fence->parent);
> s_job->s_fence->parent = NULL;
> - atomic_dec(&sched->hw_rq_count);
> + atomic_sub(s_job->submission_credits,
> + &sched->submission_count);
> } else {
> /*
> * remove job from pending_list.
> @@ -683,7 +730,7 @@ void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
> list_for_each_entry_safe(s_job, tmp, &sched->pending_list, list) {
> struct dma_fence *fence = s_job->s_fence->parent;
>
> - atomic_inc(&sched->hw_rq_count);
> + atomic_add(s_job->submission_credits, &sched->submission_count);
>
> if (!full_recovery)
> continue;
> @@ -764,6 +811,8 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs);
> * drm_sched_job_init - init a scheduler job
> * @job: scheduler job to init
> * @entity: scheduler entity to use
> + * @submission_credits: the number of credits this job contributes to the
> + * schdulers submission limit
Spelling: "schedulers"!
Please run your patch through scripts/checkpatch.pl --strict and inspect what it says.
> * @owner: job owner for debugging
> *
> * Refer to drm_sched_entity_push_job() documentation
> @@ -781,6 +830,7 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs);
> */
> int drm_sched_job_init(struct drm_sched_job *job,
> struct drm_sched_entity *entity,
> + u32 submission_credits,
> void *owner)
> {
> if (!entity->rq && !entity->single_sched)
> @@ -792,6 +842,7 @@ int drm_sched_job_init(struct drm_sched_job *job,
> return -ENOMEM;
>
> INIT_LIST_HEAD(&job->list);
> + job->submission_credits = submission_credits ? submission_credits : 1;
>
> xa_init_flags(&job->dependencies, XA_FLAGS_ALLOC);
>
> @@ -1004,12 +1055,14 @@ EXPORT_SYMBOL(drm_sched_job_cleanup);
> /**
> * drm_sched_wakeup_if_can_queue - Wake up the scheduler
> * @sched: scheduler instance
> + * @entity: the scheduler entity
> *
> * Wake up the scheduler if we can queue jobs.
> */
> -void drm_sched_wakeup_if_can_queue(struct drm_gpu_scheduler *sched)
> +void drm_sched_wakeup_if_can_queue(struct drm_gpu_scheduler *sched,
> + struct drm_sched_entity *entity)
> {
> - if (drm_sched_can_queue(sched))
> + if (drm_sched_can_queue(sched, entity))
> drm_sched_run_job_queue(sched);
> }
>
> @@ -1147,7 +1200,7 @@ static void drm_sched_run_job_work(struct work_struct *w)
>
> s_fence = sched_job->s_fence;
>
> - atomic_inc(&sched->hw_rq_count);
> + atomic_add(sched_job->submission_credits, &sched->submission_count);
> drm_sched_job_begin(sched_job);
>
> trace_drm_run_job(sched_job, entity);
> @@ -1183,7 +1236,7 @@ static void drm_sched_run_job_work(struct work_struct *w)
> * @ops: backend operations for this scheduler
> * @submit_wq: workqueue to use for submission. If NULL, an ordered wq is
> * allocated and used
> - * @hw_submission: number of hw submissions that can be in flight
> + * @max_submission_credits: number of submission credits that can be in flight
Let's not use "in flight". Perhaps it is better to say,
* @max_submission_credits: number of submission credits this scheduler can hold
* from all jobs,
> * @hang_limit: number of times to allow a job to hang before dropping it
> * @timeout: timeout value in jiffies for the scheduler
> * @timeout_wq: workqueue to use for timeout work. If NULL, the system_wq is
> @@ -1198,7 +1251,7 @@ static void drm_sched_run_job_work(struct work_struct *w)
> int drm_sched_init(struct drm_gpu_scheduler *sched,
> const struct drm_sched_backend_ops *ops,
> struct workqueue_struct *submit_wq,
> - unsigned hw_submission, unsigned hang_limit,
> + unsigned max_submission_credits, unsigned hang_limit,
> long timeout, struct workqueue_struct *timeout_wq,
> atomic_t *score, const char *name,
> enum drm_sched_policy sched_policy,
> @@ -1211,7 +1264,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
>
> sched->ops = ops;
> sched->single_entity = NULL;
> - sched->hw_submission_limit = hw_submission;
> + sched->submission_limit = max_submission_credits;
> sched->name = name;
> if (!submit_wq) {
> sched->submit_wq = alloc_ordered_workqueue(name, 0);
> @@ -1238,7 +1291,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
> init_waitqueue_head(&sched->job_scheduled);
> INIT_LIST_HEAD(&sched->pending_list);
> spin_lock_init(&sched->job_list_lock);
> - atomic_set(&sched->hw_rq_count, 0);
> + atomic_set(&sched->submission_count, 0);
> INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
> INIT_WORK(&sched->work_run_job, drm_sched_run_job_work);
> INIT_WORK(&sched->work_free_job, drm_sched_free_job_work);
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index 2e94ce788c71..8479e5302f7b 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -417,7 +417,7 @@ v3d_job_init(struct v3d_dev *v3d, struct drm_file *file_priv,
> job->free = free;
>
> ret = drm_sched_job_init(&job->base, &v3d_priv->sched_entity[queue],
> - v3d_priv);
> + 1, v3d_priv);
> if (ret)
> goto fail;
>
> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> index 27f5778bbd6d..c4a53b259585 100644
> --- a/include/drm/gpu_scheduler.h
> +++ b/include/drm/gpu_scheduler.h
> @@ -329,6 +329,8 @@ struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f);
> * @sched: the scheduler instance on which this job is scheduled.
> * @s_fence: contains the fences for the scheduling of job.
> * @finish_cb: the callback for the finished fence.
> + * @submission_credits: the number of submission credits this job contributes to
> + * the scheduler
> * @work: Helper to reschdeule job kill to different context.
> * @id: a unique id assigned to each job scheduled on the scheduler.
> * @karma: increment on every hang caused by this job. If this exceeds the hang
> @@ -348,6 +350,8 @@ struct drm_sched_job {
> struct drm_gpu_scheduler *sched;
> struct drm_sched_fence *s_fence;
>
> + u32 submission_credits;
> +
> /*
> * work is used only after finish_cb has been used and will not be
> * accessed anymore.
> @@ -471,6 +475,21 @@ struct drm_sched_backend_ops {
> * and it's time to clean it up.
> */
> void (*free_job)(struct drm_sched_job *sched_job);
> +
> + /**
> + * @update_job_credits: Called once the scheduler is considering this
> + * job for execution.
> + *
> + * Drivers may use this to update the job's submission credits, which is
> + * useful to e.g. deduct the number of native fences which have been
> + * signaled meanwhile.
> + *
> + * The callback must either return the new number of submission credits
> + * for the given job, or zero if no update is required.
> + *
> + * This callback is optional.
> + */
> + u32 (*update_job_credits)(struct drm_sched_job *sched_job);
> };
That's good.
>
> /**
> @@ -478,14 +497,14 @@ struct drm_sched_backend_ops {
> *
> * @ops: backend operations provided by the driver.
> * @single_entity: Single entity for the scheduler
> - * @hw_submission_limit: the max size of the hardware queue.
> + * @submission_limit: the maximim number of submission credits
> + * @submission_count: the number of submission credits in flight
Is this clear enough?
I mean, what really is a "submission_limit"? What is it limiting really?
Number of what? "Submissions"? No. It's credits.
("Submission" seems to have become very popular, see
Message-ID: <a39eb381-4f2b-439b-b223-c5148167b225@xxxxxxx>, maybe through Lore.)
So if "submission_credit_limit" and "submission_credit_count"
seem too wordy, (and they kind of are), then perhaps use,
@credit_limit: the credit limit of this scheduler
@credit_count: the current credit count of this scheduler
Also note the slight comment update for those two quantities.
> * @timeout: the time after which a job is removed from the scheduler.
> * @name: name of the ring for which this scheduler is being used.
> * @sched_rq: priority wise array of run queues.
> * @job_scheduled: once @drm_sched_entity_do_release is called the scheduler
> * waits on this wait queue until all the scheduled jobs are
> * finished.
> - * @hw_rq_count: the number of jobs currently in the hardware queue.
> * @job_id_count: used to assign unique id to the each job.
> * @submit_wq: workqueue used to queue @work_run_job and @work_free_job
> * @timeout_wq: workqueue used to queue @work_tdr
> @@ -511,12 +530,12 @@ struct drm_sched_backend_ops {
> struct drm_gpu_scheduler {
> const struct drm_sched_backend_ops *ops;
> struct drm_sched_entity *single_entity;
> - uint32_t hw_submission_limit;
> + u32 submission_limit;
> + atomic_t submission_count;
See above. Perhaps "credit_limit" and "credit_count".
> long timeout;
> const char *name;
> struct drm_sched_rq sched_rq[DRM_SCHED_PRIORITY_COUNT];
> wait_queue_head_t job_scheduled;
> - atomic_t hw_rq_count;
> atomic64_t job_id_count;
> struct workqueue_struct *submit_wq;
> struct workqueue_struct *timeout_wq;
> @@ -539,7 +558,7 @@ struct drm_gpu_scheduler {
> int drm_sched_init(struct drm_gpu_scheduler *sched,
> const struct drm_sched_backend_ops *ops,
> struct workqueue_struct *submit_wq,
> - uint32_t hw_submission, unsigned hang_limit,
> + uint32_t max_submission_credits, unsigned hang_limit,
> long timeout, struct workqueue_struct *timeout_wq,
> atomic_t *score, const char *name,
> enum drm_sched_policy sched_policy,
> @@ -548,6 +567,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
> void drm_sched_fini(struct drm_gpu_scheduler *sched);
> int drm_sched_job_init(struct drm_sched_job *job,
> struct drm_sched_entity *entity,
> + u32 submission_credits,
> void *owner);
> void drm_sched_job_arm(struct drm_sched_job *job);
> int drm_sched_job_add_dependency(struct drm_sched_job *job,
> @@ -570,7 +590,8 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
>
> void drm_sched_tdr_queue_imm(struct drm_gpu_scheduler *sched);
> void drm_sched_job_cleanup(struct drm_sched_job *job);
> -void drm_sched_wakeup_if_can_queue(struct drm_gpu_scheduler *sched);
> +void drm_sched_wakeup_if_can_queue(struct drm_gpu_scheduler *sched,
> + struct drm_sched_entity *entity);
> bool drm_sched_submit_ready(struct drm_gpu_scheduler *sched);
> void drm_sched_submit_stop(struct drm_gpu_scheduler *sched);
> void drm_sched_submit_start(struct drm_gpu_scheduler *sched);
--
Regards,
Luben