On 2023-11-09 19:16, 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 credit > 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 > credit count, which represents the number of credits a job contributes > to the scheduler's credit 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 > > Changes in V3: > ============== > - rebased onto V7 of the "DRM scheduler changes for Xe" series by Matt > - move up drm_sched_can_queue() instead of adding a forward declaration > (Boris) > - add a drm_sched_available_credits() helper (Boris) > - adjust control flow in drm_sched_rq_select_entity_fifo() to Luben's proposal > - re-phrase a few comments and fix a typo (Luben) > - change naming of all structures credit fields and function parameters to the > following scheme > - drm_sched_job::credits > - drm_gpu_scheduler::credit_limit > - drm_gpu_scheduler::credit_count > - drm_sched_init(..., u32 credit_limit, ...) > - drm_sched_job_init(..., u32 credits, ...) > - add proper documentation for the scheduler's job-flow control mechanism > > Changes in V4: > ============== > - address Lubens comments regarding documentation > - switch to drm_WARN() variants > - WARN_ON() drivers passing in zero job credits for both drm_sched_job_init() > and the update_job_credits() callback > - don't retry with another runq if job doesn't fit on the ring to prevent > priority inversion > - rebase onto drm-misc-next (will probably land before Matt's series) > > Changes in V5: > ============== > - fix panfrost, lima and etnaviv build > - add proposed comments regarding how the code avoids runq priority inversion > - address Lubens feedback regarding wording > - rebase onto latest drm-misc-next (XE scheduler patches) > > Changes in V6: > ============== > - rebase due to conflicts introduced meanwhile > - drm_sched_job_init(): fail with EINVAL, rather than WARN() if job->credits > is zero > - drm_sched_can_queue: truncate job->credits if they exceed the scheduler's > credit limit to guarantee forward progress > > Patch also available in [1]. > > [1] https://gitlab.freedesktop.org/nouvelles/kernel/-/commits/sched-credits/ > --- > Documentation/gpu/drm-mm.rst | 6 + > drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 2 +- > drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c | 2 +- > drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 2 +- > drivers/gpu/drm/lima/lima_device.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 +- > drivers/gpu/drm/panfrost/panfrost_job.c | 2 +- > .../gpu/drm/scheduler/gpu_scheduler_trace.h | 2 +- > drivers/gpu/drm/scheduler/sched_main.c | 168 ++++++++++++++---- > drivers/gpu/drm/v3d/v3d_gem.c | 2 +- > include/drm/gpu_scheduler.h | 28 ++- > 14 files changed, 173 insertions(+), 51 deletions(-) > > diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst > index 602010cb6894..acc5901ac840 100644 > --- a/Documentation/gpu/drm-mm.rst > +++ b/Documentation/gpu/drm-mm.rst > @@ -552,6 +552,12 @@ Overview > .. kernel-doc:: drivers/gpu/drm/scheduler/sched_main.c > :doc: Overview > > +Flow Control > +------------ > + > +.. kernel-doc:: drivers/gpu/drm/scheduler/sched_main.c > + :doc: Flow Control > + > Scheduler Function References > ----------------------------- > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c > index 1f357198533f..62bb7fc7448a 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 2416c526f9b0..3d0f8d182506 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c > @@ -535,7 +535,7 @@ 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/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c > index 9276756e1397..5105d290e72e 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c > @@ -1917,7 +1917,7 @@ static int etnaviv_gpu_rpm_suspend(struct device *dev) > u32 idle, mask; > > /* If there are any jobs in the HW queue, we're not idle */ > - if (atomic_read(&gpu->sched.hw_rq_count)) > + if (atomic_read(&gpu->sched.credit_count)) > return -EBUSY; > > /* Check whether the hardware (except FE and MC) is idle */ > diff --git a/drivers/gpu/drm/lima/lima_device.c b/drivers/gpu/drm/lima/lima_device.c > index 02cef0cea657..0bf7105c8748 100644 > --- a/drivers/gpu/drm/lima/lima_device.c > +++ b/drivers/gpu/drm/lima/lima_device.c > @@ -514,7 +514,7 @@ int lima_device_suspend(struct device *dev) > > /* check any task running */ > for (i = 0; i < lima_pipe_num; i++) { > - if (atomic_read(&ldev->pipe[i].base.hw_rq_count)) > + if (atomic_read(&ldev->pipe[i].base.credit_count)) > return -EBUSY; > } > > diff --git a/drivers/gpu/drm/lima/lima_sched.c b/drivers/gpu/drm/lima/lima_sched.c > index aa030e1f7cda..c3bf8cda8498 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 99744de6c05a..c002cabe7b9c 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 7e64b5ef90fb..1b2cc3f2e1c7 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/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c > index 6d89e24322db..f9446e197428 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_job.c > +++ b/drivers/gpu/drm/panfrost/panfrost_job.c > @@ -963,7 +963,7 @@ int panfrost_job_is_idle(struct panfrost_device *pfdev) > > for (i = 0; i < NUM_JOB_SLOTS; i++) { > /* If there are any jobs in the HW queue, we're not idle */ > - if (atomic_read(&js->queue[i].sched.hw_rq_count)) > + if (atomic_read(&js->queue[i].sched.credit_count)) > return false; > } > > diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h > index 3143ecaaff86..f8ed093b7356 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->credit_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_main.c b/drivers/gpu/drm/scheduler/sched_main.c > index 8f5e466bd582..a196019c5ba4 100644 > --- a/drivers/gpu/drm/scheduler/sched_main.c > +++ b/drivers/gpu/drm/scheduler/sched_main.c > @@ -48,6 +48,30 @@ > * through the jobs entity pointer. > */ > > +/** > + * DOC: Flow Control > + * > + * The DRM GPU scheduler provides a flow control mechanism to regulate the rate > + * in which the jobs fetched from scheduler entities are executed. > + * > + * In this context the &drm_gpu_scheduler keeps track of a driver specified > + * credit limit representing the capacity of this scheduler and a credit count; > + * every &drm_sched_job carries a driver specified number of credits. > + * > + * Once a job is executed (but not yet finished), the job's credits contribute > + * to the scheduler's credit count until the job is finished. If by executing > + * one more job the scheduler's credit count would exceed the scheduler's > + * credit limit, the job won't be executed. Instead, the scheduler will wait > + * until the credit count has decreased enough to not overflow its credit limit. > + * This implies waiting for previously executed jobs. > + * > + * Optionally, drivers may register a callback (update_job_credits) provided by > + * struct drm_sched_backend_ops to update the job's credits dynamically. The > + * scheduler executes this callback every time the scheduler considers a job for > + * execution and subsequently checks whether the job fits the scheduler's credit > + * limit. > + */ > + > #include <linux/wait.h> > #include <linux/sched.h> > #include <linux/completion.h> > @@ -75,6 +99,51 @@ int drm_sched_policy = 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, int, 0444); > > +static u32 drm_sched_available_credits(struct drm_gpu_scheduler *sched) > +{ > + u32 credits; > + > + drm_WARN_ON(sched, check_sub_overflow(sched->credit_limit, > + atomic_read(&sched->credit_count), > + &credits)); > + > + return credits; > +} > + > +/** > + * drm_sched_can_queue -- Can we queue more to the hardware? > + * @sched: scheduler instance > + * @entity: the scheduler entity > + * > + * 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, > + struct drm_sched_entity *entity) > +{ > + 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) { > + s_job->credits = sched->ops->update_job_credits(s_job); > + > + drm_WARN(sched, !s_job->credits, > + "Jobs with zero credits bypass job-flow control.\n"); That's fine. > + } > + > + /* If a job exceeds the credit limit, truncate it to the credit limit > + * itself to guarantee forward progress. > + */ > + if (drm_WARN(sched, s_job->credits > sched->credit_limit, > + "Jobs may not exceed the credit limit, truncate.\n")) > + s_job->credits = sched->credit_limit; > + > + return drm_sched_available_credits(sched) >= s_job->credits; > +} > + > static __always_inline bool drm_sched_entity_compare_before(struct rb_node *a, > const struct rb_node *b) > { > @@ -186,12 +255,18 @@ 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. > * > - * Try to find a ready entity, returns NULL if none found. > + * Try to find the next ready entity. > + * > + * Return an entity if one is found; return an error-pointer (!NULL) if an > + * entity was ready, but the scheduler had insufficient credits to accommodate > + * its job; return NULL, if no ready entity was found. > */ > static struct drm_sched_entity * > -drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq) > +drm_sched_rq_select_entity_rr(struct drm_gpu_scheduler *sched, > + struct drm_sched_rq *rq) > { > struct drm_sched_entity *entity; > > @@ -201,6 +276,14 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq) > 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)) { > + spin_unlock(&rq->lock); > + return ERR_PTR(-ENOSPC); > + } > + > rq->current_entity = entity; > reinit_completion(&entity->entity_idle); > spin_unlock(&rq->lock); > @@ -210,8 +293,15 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq) > } > > 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)) { > + spin_unlock(&rq->lock); > + return ERR_PTR(-ENOSPC); > + } > + > rq->current_entity = entity; > reinit_completion(&entity->entity_idle); > spin_unlock(&rq->lock); > @@ -230,12 +320,18 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq) > /** > * 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. > * > - * Find oldest waiting ready entity, returns NULL if none found. > + * Find oldest waiting ready entity. > + * > + * Return an entity if one is found; return an error-pointer (!NULL) if an > + * entity was ready, but the scheduler had insufficient credits to accommodate > + * its job; return NULL, if no ready entity was found. > */ > static struct drm_sched_entity * > -drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq) > +drm_sched_rq_select_entity_fifo(struct drm_gpu_scheduler *sched, > + struct drm_sched_rq *rq) > { > struct rb_node *rb; > > @@ -245,6 +341,14 @@ drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq) > > entity = rb_entry(rb, struct drm_sched_entity, rb_tree_node); > 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)) { > + spin_unlock(&rq->lock); > + return ERR_PTR(-ENOSPC); > + } > + > rq->current_entity = entity; > reinit_completion(&entity->entity_idle); > break; > @@ -302,7 +406,7 @@ 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->credits, &sched->credit_count); > atomic_dec(sched->score); > > trace_drm_sched_process_job(s_fence); > @@ -525,7 +629,7 @@ 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->credits, &sched->credit_count); > } else { > /* > * remove job from pending_list. > @@ -586,7 +690,7 @@ 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->credits, &sched->credit_count); > > if (!full_recovery) > continue; > @@ -667,6 +771,8 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs); > * drm_sched_job_init - init a scheduler job > * @job: scheduler job to init > * @entity: scheduler entity to use > + * @credits: the number of credits this job contributes to the schedulers > + * credit limit > * @owner: job owner for debugging > * > * Refer to drm_sched_entity_push_job() documentation > @@ -684,7 +790,7 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs); > */ > int drm_sched_job_init(struct drm_sched_job *job, > struct drm_sched_entity *entity, > - void *owner) > + u32 credits, void *owner) > { > if (!entity->rq) { > /* This will most likely be followed by missing frames > @@ -695,7 +801,11 @@ int drm_sched_job_init(struct drm_sched_job *job, > return -ENOENT; > } > > + if (unlikely(!credits)) > + return -EINVAL; > + This will most likely result in bad user experience (read: blank screen), and debugging this would be really hard without something to go by in the kernel log. (This was exactly the case with amdgpu when 56e449603f0ac5 ("drm/sched: Convert the GPU scheduler to variable number of run-queues") was being worked on and merged. Without the drm_err() on missing rq in the lines immediately before the hunk above returning -ENOENT, there was no indication why setting up an fb was failing very early on (blank screen).) So it is best to print a "[drm] *ERROR* "-equivalent string in the logs, so that we can make a note of this, without relying on drivers, old and new, logging that drm_sched_job_init() failed. Regards, Luben > job->entity = entity; > + job->credits = credits; > job->s_fence = drm_sched_fence_alloc(entity, owner); > if (!job->s_fence) > return -ENOMEM; > @@ -907,21 +1017,10 @@ void drm_sched_job_cleanup(struct drm_sched_job *job) > } > EXPORT_SYMBOL(drm_sched_job_cleanup); > > -/** > - * drm_sched_can_queue -- Can we queue more to the hardware? > - * @sched: scheduler instance > - * > - * Return true if we can push more jobs to the hw, otherwise false. > - */ > -static bool drm_sched_can_queue(struct drm_gpu_scheduler *sched) > -{ > - return atomic_read(&sched->hw_rq_count) < > - sched->hw_submission_limit; > -} > - > /** > * drm_sched_wakeup - Wake up the scheduler if it is ready to queue > * @sched: scheduler instance > + * @entity: the scheduler entity > * > * Wake up the scheduler if we can queue jobs. > */ > @@ -929,7 +1028,7 @@ void drm_sched_wakeup(struct drm_gpu_scheduler *sched, > struct drm_sched_entity *entity) > { > if (drm_sched_entity_is_ready(entity)) > - if (drm_sched_can_queue(sched)) > + if (drm_sched_can_queue(sched, entity)) > drm_sched_run_job_queue(sched); > } > > @@ -938,7 +1037,11 @@ void drm_sched_wakeup(struct drm_gpu_scheduler *sched, > * > * @sched: scheduler instance > * > - * Returns the entity to process or NULL if none are found. > + * Return an entity to process or NULL if none are found. > + * > + * Note, that we break out of the for-loop when "entity" is non-null, which can > + * also be an error-pointer--this assures we don't process lower priority > + * run-queues. See comments in the respectively called functions. > */ > static struct drm_sched_entity * > drm_sched_select_entity(struct drm_gpu_scheduler *sched) > @@ -946,19 +1049,16 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched) > struct drm_sched_entity *entity; > int i; > > - if (!drm_sched_can_queue(sched)) > - return NULL; > - > /* Kernel run queue has higher priority than normal run queue*/ > for (i = sched->num_rqs - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) { > entity = drm_sched_policy == DRM_SCHED_POLICY_FIFO ? > - drm_sched_rq_select_entity_fifo(sched->sched_rq[i]) : > - drm_sched_rq_select_entity_rr(sched->sched_rq[i]); > + drm_sched_rq_select_entity_fifo(sched, sched->sched_rq[i]) : > + drm_sched_rq_select_entity_rr(sched, sched->sched_rq[i]); > if (entity) > break; > } > > - return entity; > + return IS_ERR(entity) ? NULL : entity; > } > > /** > @@ -1094,7 +1194,7 @@ 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->credits, &sched->credit_count); > drm_sched_job_begin(sched_job); > > trace_drm_run_job(sched_job, entity); > @@ -1129,7 +1229,7 @@ static void drm_sched_run_job_work(struct work_struct *w) > * @submit_wq: workqueue to use for submission. If NULL, an ordered wq is > * allocated and used > * @num_rqs: number of runqueues, one for each priority, up to DRM_SCHED_PRIORITY_COUNT > - * @hw_submission: number of hw submissions that can be in flight > + * @credit_limit: the number of 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 > @@ -1143,14 +1243,14 @@ 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, > - u32 num_rqs, uint32_t hw_submission, unsigned int hang_limit, > + u32 num_rqs, u32 credit_limit, unsigned int hang_limit, > long timeout, struct workqueue_struct *timeout_wq, > atomic_t *score, const char *name, struct device *dev) > { > int i, ret; > > sched->ops = ops; > - sched->hw_submission_limit = hw_submission; > + sched->credit_limit = credit_limit; > sched->name = name; > sched->timeout = timeout; > sched->timeout_wq = timeout_wq ? : system_wq; > @@ -1199,7 +1299,7 @@ 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->credit_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 712675134c04..9d2ac23c29e3 100644 > --- a/drivers/gpu/drm/v3d/v3d_gem.c > +++ b/drivers/gpu/drm/v3d/v3d_gem.c > @@ -418,7 +418,7 @@ v3d_job_init(struct v3d_dev *v3d, struct drm_file *file_priv, > job->file = file_priv; > > 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 09916c84703f..1d60eab747de 100644 > --- a/include/drm/gpu_scheduler.h > +++ b/include/drm/gpu_scheduler.h > @@ -321,6 +321,7 @@ 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. > + * @credits: the number of 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 > @@ -340,6 +341,8 @@ struct drm_sched_job { > struct drm_gpu_scheduler *sched; > struct drm_sched_fence *s_fence; > > + u32 credits; > + > /* > * work is used only after finish_cb has been used and will not be > * accessed anymore. > @@ -463,13 +466,27 @@ 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 when the scheduler is considering this > + * job for execution. > + * > + * This callback returns the number of credits the job would take if > + * pushed to the hardware. Drivers may use this to dynamically update > + * the job's credit count. For instance, deduct the number of credits > + * for already signalled native fences. > + * > + * This callback is optional. > + */ > + u32 (*update_job_credits)(struct drm_sched_job *sched_job); > }; > > /** > * struct drm_gpu_scheduler - scheduler instance-specific data > * > * @ops: backend operations provided by the driver. > - * @hw_submission_limit: the max size of the hardware queue. > + * @credit_limit: the credit limit of this scheduler > + * @credit_count: the current credit count of this scheduler > * @timeout: the time after which a job is removed from the scheduler. > * @name: name of the ring for which this scheduler is being used. > * @num_rqs: Number of run-queues. This is at most DRM_SCHED_PRIORITY_COUNT, > @@ -478,7 +495,6 @@ struct drm_sched_backend_ops { > * @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 > @@ -502,13 +518,13 @@ struct drm_sched_backend_ops { > */ > struct drm_gpu_scheduler { > const struct drm_sched_backend_ops *ops; > - uint32_t hw_submission_limit; > + u32 credit_limit; > + atomic_t credit_count; > long timeout; > const char *name; > u32 num_rqs; > struct drm_sched_rq **sched_rq; > 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; > @@ -530,14 +546,14 @@ 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, > - u32 num_rqs, uint32_t hw_submission, unsigned int hang_limit, > + u32 num_rqs, u32 credit_limit, unsigned int hang_limit, > long timeout, struct workqueue_struct *timeout_wq, > atomic_t *score, const char *name, struct device *dev); > > void drm_sched_fini(struct drm_gpu_scheduler *sched); > int drm_sched_job_init(struct drm_sched_job *job, > struct drm_sched_entity *entity, > - void *owner); > + u32 credits, void *owner); > void drm_sched_job_arm(struct drm_sched_job *job); > int drm_sched_job_add_dependency(struct drm_sched_job *job, > struct dma_fence *fence); > > base-commit: f3123c2590005c5ff631653d31428e40cd10c618
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