Am Donnerstag, dem 24.06.2021 um 16:00 +0200 schrieb Daniel Vetter:
> Instead of just a callback we can just glue in the gem helpers that
> panfrost, v3d and lima currently use. There's really not that many
> ways to skin this cat.
>
> On the naming bikeshed: The idea for using _await_ to denote adding
> dependencies to a job comes from i915, where that's used quite
> extensively all over the place, in lots of datastructures.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> Cc: "Christian König" <christian.koenig@xxxxxxx>
> Cc: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
> Cc: Lee Jones <lee.jones@xxxxxxxxxx>
> Cc: Nirmoy Das <nirmoy.aiemd@xxxxxxxxx>
> Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Cc: Luben Tuikov <luben.tuikov@xxxxxxx>
> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> Cc: Jack Zhang <Jack.Zhang1@xxxxxxx>
> Cc: linux-media@xxxxxxxxxxxxxxx
> Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
> ---
> drivers/gpu/drm/scheduler/sched_entity.c | 18 +++-
> drivers/gpu/drm/scheduler/sched_main.c | 103 +++++++++++++++++++++++
> include/drm/gpu_scheduler.h | 31 ++++++-
> 3 files changed, 146 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index f7347c284886..b6f72fafd504 100644
> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> @@ -211,6 +211,19 @@ static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
> job->sched->ops->free_job(job);
> }
>
> +static struct dma_fence *
> +drm_sched_job_dependency(struct drm_sched_job *job,
> + struct drm_sched_entity *entity)
> +{
> + if (!xa_empty(&job->dependencies))
> + return xa_erase(&job->dependencies, job->last_dependency++);
Not sure how much it buys us now that you dedup fences before adding
them to the xa, but we could avoid potentially avoid some ping-pong
looping in the scheduler by checking if the fence we are about to
return here is already signaled and skipping to the next one if so.
Regards,
Lucas
> +
> + if (job->sched->ops->dependency)
> + return job->sched->ops->dependency(job, entity);
> +
> + return NULL;
> +}
> +
> /**
> * drm_sched_entity_kill_jobs - Make sure all remaining jobs are killed
> *
> @@ -229,7 +242,7 @@ static void drm_sched_entity_kill_jobs(struct drm_sched_entity *entity)
> struct drm_sched_fence *s_fence = job->s_fence;
>
> /* Wait for all dependencies to avoid data corruptions */
> - while ((f = job->sched->ops->dependency(job, entity)))
> + while ((f = drm_sched_job_dependency(job, entity)))
> dma_fence_wait(f, false);
>
> drm_sched_fence_scheduled(s_fence);
> @@ -419,7 +432,6 @@ static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
> */
> struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
> {
> - struct drm_gpu_scheduler *sched = entity->rq->sched;
> struct drm_sched_job *sched_job;
>
> sched_job = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
> @@ -427,7 +439,7 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
> return NULL;
>
> while ((entity->dependency =
> - sched->ops->dependency(sched_job, entity))) {
> + drm_sched_job_dependency(sched_job, entity))) {
> trace_drm_sched_job_wait_dep(sched_job, entity->dependency);
>
> if (drm_sched_entity_add_dependency_cb(entity))
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> index 70eefed17e06..370c336d383f 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -603,6 +603,8 @@ int drm_sched_job_init(struct drm_sched_job *job,
>
> INIT_LIST_HEAD(&job->list);
>
> + xa_init_flags(&job->dependencies, XA_FLAGS_ALLOC);
> +
> return 0;
> }
> EXPORT_SYMBOL(drm_sched_job_init);
> @@ -626,6 +628,98 @@ void drm_sched_job_arm(struct drm_sched_job *job)
> }
> EXPORT_SYMBOL(drm_sched_job_arm);
>
> +/**
> + * drm_sched_job_await_fence - adds the fence as a job dependency
> + * @job: scheduler job to add the dependencies to
> + * @fence: the dma_fence to add to the list of dependencies.
> + *
> + * Note that @fence is consumed in both the success and error cases.
> + *
> + * Returns:
> + * 0 on success, or an error on failing to expand the array.
> + */
> +int drm_sched_job_await_fence(struct drm_sched_job *job,
> + struct dma_fence *fence)
> +{
> + struct dma_fence *entry;
> + unsigned long index;
> + u32 id = 0;
> + int ret;
> +
> + if (!fence)
> + return 0;
> +
> + /* Deduplicate if we already depend on a fence from the same context.
> + * This lets the size of the array of deps scale with the number of
> + * engines involved, rather than the number of BOs.
> + */
> + xa_for_each(&job->dependencies, index, entry) {
> + if (entry->context != fence->context)
> + continue;
> +
> + if (dma_fence_is_later(fence, entry)) {
> + dma_fence_put(entry);
> + xa_store(&job->dependencies, index, fence, GFP_KERNEL);
> + } else {
> + dma_fence_put(fence);
> + }
> + return 0;
> + }
> +
> + ret = xa_alloc(&job->dependencies, &id, fence, xa_limit_32b, GFP_KERNEL);
> + if (ret != 0)
> + dma_fence_put(fence);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(drm_sched_job_await_fence);
> +
> +/**
> + * drm_sched_job_await_implicit - adds implicit dependencies as job dependencies
> + * @job: scheduler job to add the dependencies to
> + * @obj: the gem object to add new dependencies from.
> + * @write: whether the job might write the object (so we need to depend on
> + * shared fences in the reservation object).
> + *
> + * This should be called after drm_gem_lock_reservations() on your array of
> + * GEM objects used in the job but before updating the reservations with your
> + * own fences.
> + *
> + * Returns:
> + * 0 on success, or an error on failing to expand the array.
> + */
> +int drm_sched_job_await_implicit(struct drm_sched_job *job,
> + struct drm_gem_object *obj,
> + bool write)
> +{
> + int ret;
> + struct dma_fence **fences;
> + unsigned int i, fence_count;
> +
> + if (!write) {
> + struct dma_fence *fence = dma_resv_get_excl_unlocked(obj->resv);
> +
> + return drm_sched_job_await_fence(job, fence);
> + }
> +
> + ret = dma_resv_get_fences(obj->resv, NULL, &fence_count, &fences);
> + if (ret || !fence_count)
> + return ret;
> +
> + for (i = 0; i < fence_count; i++) {
> + ret = drm_sched_job_await_fence(job, fences[i]);
> + if (ret)
> + break;
> + }
> +
> + for (; i < fence_count; i++)
> + dma_fence_put(fences[i]);
> + kfree(fences);
> + return ret;
> +}
> +EXPORT_SYMBOL(drm_sched_job_await_implicit);
> +
> +
> /**
> * drm_sched_job_cleanup - clean up scheduler job resources
> *
> @@ -633,8 +727,17 @@ EXPORT_SYMBOL(drm_sched_job_arm);
> */
> void drm_sched_job_cleanup(struct drm_sched_job *job)
> {
> + struct dma_fence *fence;
> + unsigned long index;
> +
> dma_fence_put(&job->s_fence->finished);
> job->s_fence = NULL;
> +
> + xa_for_each(&job->dependencies, index, fence) {
> + dma_fence_put(fence);
> + }
> + xa_destroy(&job->dependencies);
> +
> }
> EXPORT_SYMBOL(drm_sched_job_cleanup);
>
> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> index 80438d126c9d..e4d7e1496296 100644
> --- a/include/drm/gpu_scheduler.h
> +++ b/include/drm/gpu_scheduler.h
> @@ -27,9 +27,12 @@
> #include <drm/spsc_queue.h>
> #include <linux/dma-fence.h>
> #include <linux/completion.h>
> +#include <linux/xarray.h>
>
> #define MAX_WAIT_SCHED_ENTITY_Q_EMPTY msecs_to_jiffies(1000)
>
> +struct drm_gem_object;
> +
> struct drm_gpu_scheduler;
> struct drm_sched_rq;
>
> @@ -198,6 +201,16 @@ struct drm_sched_job {
> enum drm_sched_priority s_priority;
> struct drm_sched_entity *entity;
> struct dma_fence_cb cb;
> + /**
> + * @dependencies:
> + *
> + * Contains the dependencies as struct dma_fence for this job, see
> + * drm_sched_job_await_fence() and drm_sched_job_await_implicit().
> + */
> + struct xarray dependencies;
> +
> + /** @last_dependency: tracks @dependencies as they signal */
> + unsigned long last_dependency;
> };
>
> static inline bool drm_sched_invalidate_job(struct drm_sched_job *s_job,
> @@ -220,9 +233,14 @@ enum drm_gpu_sched_stat {
> */
> struct drm_sched_backend_ops {
> /**
> - * @dependency: Called when the scheduler is considering scheduling
> - * this job next, to get another struct dma_fence for this job to
> - * block on. Once it returns NULL, run_job() may be called.
> + * @dependency:
> + *
> + * Called when the scheduler is considering scheduling this job next, to
> + * get another struct dma_fence for this job to block on. Once it
> + * returns NULL, run_job() may be called.
> + *
> + * If a driver exclusively uses drm_sched_job_await_fence() and
> + * drm_sched_job_await_implicit() this can be ommitted and left as NULL.
> */
> struct dma_fence *(*dependency)(struct drm_sched_job *sched_job,
> struct drm_sched_entity *s_entity);
> @@ -314,6 +332,13 @@ int drm_sched_job_init(struct drm_sched_job *job,
> struct drm_sched_entity *entity,
> void *owner);
> void drm_sched_job_arm(struct drm_sched_job *job);
> +int drm_sched_job_await_fence(struct drm_sched_job *job,
> + struct dma_fence *fence);
> +int drm_sched_job_await_implicit(struct drm_sched_job *job,
> + struct drm_gem_object *obj,
> + bool write);
> +
> +
> void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
> struct drm_gpu_scheduler **sched_list,
> unsigned int num_sched_list);
