On Wed, Sep 27, 2023 at 10:36:49AM -0400, Luben Tuikov wrote: > Hi, > > On 2023-09-19 01:01, Matthew Brost wrote: > > DRM_SCHED_POLICY_SINGLE_ENTITY creates a 1 to 1 relationship between > > scheduler and entity. No priorities or run queue used in this mode. > > Intended for devices with firmware schedulers. > > > > v2: > > - Drop sched / rq union (Luben) > > v3: > > - Don't pick entity if stopped in drm_sched_select_entity (Danilo) > > > > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx> > > --- > > drivers/gpu/drm/scheduler/sched_entity.c | 69 ++++++++++++++++++------ > > drivers/gpu/drm/scheduler/sched_fence.c | 2 +- > > drivers/gpu/drm/scheduler/sched_main.c | 64 +++++++++++++++++++--- > > include/drm/gpu_scheduler.h | 8 +++ > > 4 files changed, 120 insertions(+), 23 deletions(-) > > > > diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c > > index cf42e2265d64..437c50867c99 100644 > > --- a/drivers/gpu/drm/scheduler/sched_entity.c > > +++ b/drivers/gpu/drm/scheduler/sched_entity.c > > @@ -83,6 +83,7 @@ int drm_sched_entity_init(struct drm_sched_entity *entity, > > memset(entity, 0, sizeof(struct drm_sched_entity)); > > INIT_LIST_HEAD(&entity->list); > > entity->rq = NULL; > > + entity->single_sched = NULL; > > entity->guilty = guilty; > > entity->num_sched_list = num_sched_list; > > entity->priority = priority; > > @@ -90,8 +91,17 @@ int drm_sched_entity_init(struct drm_sched_entity *entity, > > RCU_INIT_POINTER(entity->last_scheduled, NULL); > > RB_CLEAR_NODE(&entity->rb_tree_node); > > > > - if(num_sched_list) > > - entity->rq = &sched_list[0]->sched_rq[entity->priority]; > > + if (num_sched_list) { > > + if (sched_list[0]->sched_policy != > > + DRM_SCHED_POLICY_SINGLE_ENTITY) { > > + entity->rq = &sched_list[0]->sched_rq[entity->priority]; > > + } else { > > + if (num_sched_list != 1 || sched_list[0]->single_entity) > > + return -EINVAL; > > + sched_list[0]->single_entity = entity; > > + entity->single_sched = sched_list[0]; > > + } > > + } > > So much (checking for) negativity...:-) > Perhaps the simplified form below? > > if (num_sched_list) { > if (sched_list[0]->sched_policy != > DRM_SCHED_POLICY_SINGLE_ENTITY) { > entity->rq = &sched_list[0]->sched_rq[entity->priority]; > } else if (num_sched_list == 1 && !sched_list[0]->single_entity) { > sched_list[0]->single_entity = entity; > entity->single_sched = sched_list[0]; > } else { > return -EINVAL; > } > } > Will change. > > > > init_completion(&entity->entity_idle); > > > > @@ -124,7 +134,8 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity, > > struct drm_gpu_scheduler **sched_list, > > unsigned int num_sched_list) > > { > > - WARN_ON(!num_sched_list || !sched_list); > > + WARN_ON(!num_sched_list || !sched_list || > > + !!entity->single_sched); > > > > entity->sched_list = sched_list; > > entity->num_sched_list = num_sched_list; > > @@ -231,13 +242,15 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity) > > { > > struct drm_sched_job *job; > > struct dma_fence *prev; > > + bool single_entity = !!entity->single_sched; > > > > - if (!entity->rq) > > + if (!entity->rq && !single_entity) > > return; > > > > spin_lock(&entity->rq_lock); > > entity->stopped = true; > > - drm_sched_rq_remove_entity(entity->rq, entity); > > + if (!single_entity) > > + drm_sched_rq_remove_entity(entity->rq, entity); > > spin_unlock(&entity->rq_lock); > > > > /* Make sure this entity is not used by the scheduler at the moment */ > > @@ -259,6 +272,20 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity) > > dma_fence_put(prev); > > } > > > > +/** > > + * drm_sched_entity_to_scheduler - Schedule entity to GPU scheduler > > Please use verbs. Please? > > Fix: > /** > * drm_sched_entity_to_scheduler - Map a schedule entity to a GPU scheduler > > > + * @entity: scheduler entity > > + * > > + * Returns GPU scheduler for the entity > > Fix: > * Given an entity, return its GPU scheduler. > Yep. > > + */ > > +struct drm_gpu_scheduler * > > +drm_sched_entity_to_scheduler(struct drm_sched_entity *entity) > > +{ > > + bool single_entity = !!entity->single_sched; > > + > > + return single_entity ? entity->single_sched : entity->rq->sched; > > +} > > + > > /** > > * drm_sched_entity_flush - Flush a context entity > > * > > @@ -276,11 +303,12 @@ long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout) > > struct drm_gpu_scheduler *sched; > > struct task_struct *last_user; > > long ret = timeout; > > + bool single_entity = !!entity->single_sched; > > > > - if (!entity->rq) > > + if (!entity->rq && !single_entity) > > return 0; > > > > - sched = entity->rq->sched; > > + sched = drm_sched_entity_to_scheduler(entity); > > /** > > * The client will not queue more IBs during this fini, consume existing > > * queued IBs or discard them on SIGKILL > > @@ -373,7 +401,7 @@ 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(entity->rq->sched); > > + drm_sched_wakeup_if_can_queue(drm_sched_entity_to_scheduler(entity)); > > } > > > > /** > > @@ -387,6 +415,8 @@ static void drm_sched_entity_wakeup(struct dma_fence *f, > > void drm_sched_entity_set_priority(struct drm_sched_entity *entity, > > enum drm_sched_priority priority) > > { > > + WARN_ON(!!entity->single_sched); > > + > > spin_lock(&entity->rq_lock); > > entity->priority = priority; > > spin_unlock(&entity->rq_lock); > > @@ -399,7 +429,7 @@ EXPORT_SYMBOL(drm_sched_entity_set_priority); > > */ > > static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity) > > { > > - struct drm_gpu_scheduler *sched = entity->rq->sched; > > + struct drm_gpu_scheduler *sched = drm_sched_entity_to_scheduler(entity); > > struct dma_fence *fence = entity->dependency; > > struct drm_sched_fence *s_fence; > > > > @@ -501,7 +531,8 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity) > > * Update the entity's location in the min heap according to > > * the timestamp of the next job, if any. > > */ > > - if (entity->rq->sched->sched_policy == DRM_SCHED_POLICY_FIFO) { > > + if (drm_sched_entity_to_scheduler(entity)->sched_policy == > > + DRM_SCHED_POLICY_FIFO) { > > struct drm_sched_job *next; > > > > next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue)); > > @@ -524,6 +555,8 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity) > > struct drm_gpu_scheduler *sched; > > struct drm_sched_rq *rq; > > > > + WARN_ON(!!entity->single_sched); > > + > > /* single possible engine and already selected */ > > if (!entity->sched_list) > > return; > > @@ -573,12 +606,13 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity) > > void drm_sched_entity_push_job(struct drm_sched_job *sched_job) > > { > > struct drm_sched_entity *entity = sched_job->entity; > > - bool first, fifo = entity->rq->sched->sched_policy == > > - DRM_SCHED_POLICY_FIFO; > > + bool single_entity = !!entity->single_sched; > > + bool first; > > ktime_t submit_ts; > > > > trace_drm_sched_job(sched_job, entity); > > - atomic_inc(entity->rq->sched->score); > > + if (!single_entity) > > + atomic_inc(entity->rq->sched->score); > > WRITE_ONCE(entity->last_user, current->group_leader); > > > > /* > > @@ -591,6 +625,10 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job) > > > > /* first job wakes up scheduler */ > > if (first) { > > + struct drm_gpu_scheduler *sched = > > + drm_sched_entity_to_scheduler(entity); > > + bool fifo = sched->sched_policy == DRM_SCHED_POLICY_FIFO; > > + > > /* Add the entity to the run queue */ > > spin_lock(&entity->rq_lock); > > if (entity->stopped) { > > @@ -600,13 +638,14 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job) > > return; > > } > > > > - drm_sched_rq_add_entity(entity->rq, entity); > > + if (!single_entity) > > + drm_sched_rq_add_entity(entity->rq, entity); > > spin_unlock(&entity->rq_lock); > > > > if (fifo) > > drm_sched_rq_update_fifo(entity, submit_ts); > > > > - drm_sched_wakeup_if_can_queue(entity->rq->sched); > > + drm_sched_wakeup_if_can_queue(sched); > > } > > } > > EXPORT_SYMBOL(drm_sched_entity_push_job); > > diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c > > index 06cedfe4b486..f6b926f5e188 100644 > > --- a/drivers/gpu/drm/scheduler/sched_fence.c > > +++ b/drivers/gpu/drm/scheduler/sched_fence.c > > @@ -225,7 +225,7 @@ void drm_sched_fence_init(struct drm_sched_fence *fence, > > { > > unsigned seq; > > > > - fence->sched = entity->rq->sched; > > + fence->sched = drm_sched_entity_to_scheduler(entity); > > seq = atomic_inc_return(&entity->fence_seq); > > dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled, > > &fence->lock, entity->fence_context, seq); > > diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c > > index f645f32977ed..588c735f7498 100644 > > --- a/drivers/gpu/drm/scheduler/sched_main.c > > +++ b/drivers/gpu/drm/scheduler/sched_main.c > > @@ -32,7 +32,8 @@ > > * backend operations to the scheduler like submitting a job to hardware run queue, > > * returning the dependencies of a job etc. > > * > > - * The organisation of the scheduler is the following: > > + * The organisation of the scheduler is the following for scheduling policies > > + * DRM_SCHED_POLICY_RR and DRM_SCHED_POLICY_FIFO: > > Yes, so this was badly written to begin with. If we're adding more information, > I'd write: > > * For scheduling policies DRM_SCHED_POLICY_RR and DRM_SCHED_POLICY_FIFO, > * the scheduler organization is, Yep. > > > * > > * 1. Each hw run queue has one scheduler > > * 2. Each scheduler has multiple run queues with different priorities > > @@ -43,6 +44,23 @@ > > * > > * The jobs in a entity are always scheduled in the order that they were pushed. > > * > > + * The organisation of the scheduler is the following for scheduling policy > > + * DRM_SCHED_POLICY_SINGLE_ENTITY: > > Remember, it's a list, on large enough scale, thus, > > * For DRM_SCHED_POLICY_SINGLE_ENTITY, the organization of the scheduler is, > > > + * > > + * 1. One to one relationship between scheduler and entity > > + * 2. No priorities implemented per scheduler (single job queue) > > + * 3. No run queues in scheduler rather jobs are directly dequeued from entity > > + * 4. The entity maintains a queue of jobs that will be scheduled on the > > + * hardware > > Good! But please fix, > > 4. The entity maintains a queue of jobs that will be scheduler _to_ the hardware. > > > + * > > + * The jobs in a entity are always scheduled in the order that they were pushed > > + * regardless of scheduling policy. > > Please add here, > Single-entity scheduling is essentially a FIFO for jobs. > > > + * > > + * A policy of DRM_SCHED_POLICY_RR or DRM_SCHED_POLICY_FIFO is expected to used > > "... is expected to _be_ used ..." > > > + * when the KMD is scheduling directly on the hardware while a scheduling policy > > I'd spell out "kernel-mode driver" since it makes it terse when reading a processed > DOC format, and having a three-letter abbreviation spelled out makes for an easier > reading experience. (There are too many three-letter abbreviations as is...) > > "... directly _to_ the hardware ..." since, ultimately, the DRM scheduler just > pushes jobs to be executed to the hardware by the hardware and doesn't support > or control hardware preemption of jobs _on_ the hardware. (See what I did there? :-) ) > > > + * of DRM_SCHED_POLICY_SINGLE_ENTITY is expected to be used when there is a > > + * firmware scheduler. > > + * > > Yeah, so that's a good explanation--thanks for writing this. > > > * Note that once a job was taken from the entities queue and pushed to the > > Please only use present tense in software documentation. No past, future, or > perfect tenses please. > > * Note that once a job _is_ taken from the entities queue and pushed to the > > > * hardware, i.e. the pending queue, the entity must not be referenced anymore > > * through the jobs entity pointer. > > Yeah, another good explanation--thanks for including this. > Yes to all the wordin changes. > > @@ -96,6 +114,8 @@ static inline void drm_sched_rq_remove_fifo_locked(struct drm_sched_entity *enti > > > > void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts) > > { > > + WARN_ON(!!entity->single_sched); > > + > > /* > > * Both locks need to be grabbed, one to protect from entity->rq change > > * for entity from within concurrent drm_sched_entity_select_rq and the > > @@ -126,6 +146,8 @@ void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts) > > static void drm_sched_rq_init(struct drm_gpu_scheduler *sched, > > struct drm_sched_rq *rq) > > { > > + WARN_ON(sched->sched_policy == DRM_SCHED_POLICY_SINGLE_ENTITY); > > + > > spin_lock_init(&rq->lock); > > INIT_LIST_HEAD(&rq->entities); > > rq->rb_tree_root = RB_ROOT_CACHED; > > @@ -144,6 +166,8 @@ static void drm_sched_rq_init(struct drm_gpu_scheduler *sched, > > void drm_sched_rq_add_entity(struct drm_sched_rq *rq, > > struct drm_sched_entity *entity) > > { > > + WARN_ON(!!entity->single_sched); > > + > > if (!list_empty(&entity->list)) > > return; > > > > @@ -166,6 +190,8 @@ void drm_sched_rq_add_entity(struct drm_sched_rq *rq, > > void drm_sched_rq_remove_entity(struct drm_sched_rq *rq, > > struct drm_sched_entity *entity) > > { > > + WARN_ON(!!entity->single_sched); > > + > > if (list_empty(&entity->list)) > > return; > > > > @@ -641,7 +667,7 @@ int drm_sched_job_init(struct drm_sched_job *job, > > struct drm_sched_entity *entity, > > void *owner) > > { > > - if (!entity->rq) > > + if (!entity->rq && !entity->single_sched) > > return -ENOENT; > > > > job->entity = entity; > > @@ -674,13 +700,16 @@ void drm_sched_job_arm(struct drm_sched_job *job) > > { > > struct drm_gpu_scheduler *sched; > > struct drm_sched_entity *entity = job->entity; > > + bool single_entity = !!entity->single_sched; > > > > BUG_ON(!entity); > > - drm_sched_entity_select_rq(entity); > > - sched = entity->rq->sched; > > + if (!single_entity) > > + drm_sched_entity_select_rq(entity); > > + sched = drm_sched_entity_to_scheduler(entity); > > So here, I wonder, and I've a tiny exploratory request: > Could we "fake" an rq for the single-entity and thus remove (become unnecessary) > all those "if (single-entity)" and "if (!single-entity)". > > If we keep adding code peppered with if () everywhere, over the years it'll become > hard to read. However, if we use maps to achieve choice and selection, such as entity->rq, > then you'd not need much of the "if (single-entity)" and "if (!single-entity)", > and the code would naturally stay mostly the same and the sched selection would > still be abstracted out via the entity->rq. > > What do you think? > I looked into this a little and can't really think of an easy way to do this. Wouldn't we just end up with a similar number of checks in the rq code? I'd say for now let's just live the if / else in a few places. If we start adding more scheduling modes then perhaps we explore another approach. > > > > job->sched = sched; > > - job->s_priority = entity->rq - sched->sched_rq; > > + if (!single_entity) > > + job->s_priority = entity->rq - sched->sched_rq; > > job->id = atomic64_inc_return(&sched->job_id_count); > > > > drm_sched_fence_init(job->s_fence, job->entity); > > @@ -896,6 +925,14 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched) > > 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)) > > + return sched->single_entity; > > + > > + return NULL; > > + } > > + > > /* 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 ? > > @@ -1092,6 +1129,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched, > > return -EINVAL; > > > > sched->ops = ops; > > + sched->single_entity = NULL; > > sched->hw_submission_limit = hw_submission; > > sched->name = name; > > if (!submit_wq) { > > @@ -1111,7 +1149,9 @@ int drm_sched_init(struct drm_gpu_scheduler *sched, > > sched->dev = dev; > > sched->sched_policy = sched_policy == DRM_SCHED_POLICY_UNSET ? > > drm_sched_policy_default : sched_policy; > > - for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_COUNT; i++) > > + for (i = DRM_SCHED_PRIORITY_MIN; sched_policy != > > + DRM_SCHED_POLICY_SINGLE_ENTITY && i < DRM_SCHED_PRIORITY_COUNT; > > + i++) > > So, "sched_policy != DRM_SCHED_POLICY_SINGLE_ENTITY" doesn't seem to be > a loop-invariant, since it doesn't cause the loop to exit over iterations. > It's just a gate to executing the loop. I am used to seeing only loop > invariants in the for-loop conditional. > > I wonder if it is clearer to just say what is meant: > > if (sched_policy != DRM_SCHED_POLICY_SINGLE_ENTITY) { > for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_COUNT; i++) > ... > } > Sure, will add if statement. > On a larger scheme of things, I believe it is a bit presumptuous to say: > > struct drm_gpu_scheduler { > ... > struct drm_sched_rq sched_rq[DRM_SCHED_PRIORITY_COUNT]; > ... > }; > > I mean, why does a scheduler have to implement all those priorities? Maybe it > wants to implement only one. :-) > > Perhaps we can have, > > struct drm_gpu_scheduler { > ... > u32 num_rqs; > struct drm_sched_rq *sched_rq; > ... > }; > > Which might make it easier to fake out an rq for single-entity and then leave > the code mostly intact, while also implementing single-entity. > > It's not a gating issue, but perhaps it would create a cleaner code in the long > run? Maybe we should explore this? > See above. I'd vote for leave this as is for now. > > drm_sched_rq_init(sched, &sched->sched_rq[i]); > > > > init_waitqueue_head(&sched->job_scheduled); > > @@ -1143,7 +1183,15 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched) > > > > drm_sched_submit_stop(sched); > > > > - for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) { > > + if (sched->single_entity) { > > + spin_lock(&sched->single_entity->rq_lock); > > + sched->single_entity->stopped = true; > > + spin_unlock(&sched->single_entity->rq_lock); > > + } > > + > > + for (i = DRM_SCHED_PRIORITY_COUNT - 1; sched->sched_policy != > > + DRM_SCHED_POLICY_SINGLE_ENTITY && i >= DRM_SCHED_PRIORITY_MIN; > > + i--) { > > struct drm_sched_rq *rq = &sched->sched_rq[i]; > > Same sentiment here, as above. Got it. Matt > -- > Regards, > Luben > > > > > spin_lock(&rq->lock); > > @@ -1186,6 +1234,8 @@ void drm_sched_increase_karma(struct drm_sched_job *bad) > > struct drm_sched_entity *entity; > > struct drm_gpu_scheduler *sched = bad->sched; > > > > + WARN_ON(sched->sched_policy == DRM_SCHED_POLICY_SINGLE_ENTITY); > > + > > /* don't change @bad's karma if it's from KERNEL RQ, > > * because sometimes GPU hang would cause kernel jobs (like VM updating jobs) > > * corrupt but keep in mind that kernel jobs always considered good. > > diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h > > index 9f830ff84bad..655675f797ea 100644 > > --- a/include/drm/gpu_scheduler.h > > +++ b/include/drm/gpu_scheduler.h > > @@ -79,6 +79,7 @@ enum drm_sched_policy { > > DRM_SCHED_POLICY_UNSET, > > DRM_SCHED_POLICY_RR, > > DRM_SCHED_POLICY_FIFO, > > + DRM_SCHED_POLICY_SINGLE_ENTITY, > > DRM_SCHED_POLICY_COUNT, > > }; > > > > @@ -112,6 +113,9 @@ struct drm_sched_entity { > > */ > > struct drm_sched_rq *rq; > > > > + /** @single_sched: Single scheduler */ > > + struct drm_gpu_scheduler *single_sched; > > + > > /** > > * @sched_list: > > * > > @@ -473,6 +477,7 @@ struct drm_sched_backend_ops { > > * struct drm_gpu_scheduler - scheduler instance-specific data > > * > > * @ops: backend operations provided by the driver. > > + * @single_entity: Single entity for the scheduler > > * @hw_submission_limit: the max size of the hardware queue. > > * @timeout: the time after which a job is removed from the scheduler. > > * @name: name of the ring for which this scheduler is being used. > > @@ -504,6 +509,7 @@ 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; > > long timeout; > > const char *name; > > @@ -587,6 +593,8 @@ int drm_sched_entity_init(struct drm_sched_entity *entity, > > struct drm_gpu_scheduler **sched_list, > > unsigned int num_sched_list, > > atomic_t *guilty); > > +struct drm_gpu_scheduler * > > +drm_sched_entity_to_scheduler(struct drm_sched_entity *entity); > > long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout); > > void drm_sched_entity_fini(struct drm_sched_entity *entity); > > void drm_sched_entity_destroy(struct drm_sched_entity *entity); >