Re: [PATCH v5 04/20] drm/sched: Add dependency tracking

Christian König
2021-08-05T13:47:25Z

Am 05.08.21 um 12:46 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.
>
> v2/3: Rebased.
>
> v4: Repaint this shed. The functions are now called _add_dependency()
> and _add_implicit_dependency()
>
> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> (v3)
> Reviewed-by: Steven Price <steven.price@arm.com> (v1)
> Acked-by: Melissa Wen <mwen@igalia.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: "Christian König" <christian.koenig@amd.com>
> Cc: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Nirmoy Das <nirmoy.aiemd@gmail.com>
> Cc: Boris Brezillon <boris.brezillon@collabora.com>
> Cc: Luben Tuikov <luben.tuikov@amd.com>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: linux-media@vger.kernel.org
> Cc: linaro-mm-sig@lists.linaro.org
> ---
> drivers/gpu/drm/scheduler/sched_entity.c | 18 +++-
> drivers/gpu/drm/scheduler/sched_main.c | 104 +++++++++++++++++++++++
> include/drm/gpu_scheduler.h | 33 ++++++-
> 3 files changed, 149 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index 89e3f6eaf519..381fbf462ea7 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++);
> +
> + 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 454cb6164bdc..f77456929139 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);
> @@ -637,6 +639,99 @@ void drm_sched_job_arm(struct drm_sched_job *job)
> }
> EXPORT_SYMBOL(drm_sched_job_arm);
>
> +/**
> + * drm_sched_job_add_dependency - 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_add_dependency(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_add_dependency);
> +
> +/**
> + * drm_sched_job_add_implicit_dependencies - 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_add_implicit_dependencies(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_add_dependency(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_add_dependency(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_add_implicit_dependencies);
> +
> +
> /**
> * drm_sched_job_cleanup - clean up scheduler job resources
> * @job: scheduler job to clean up
> @@ -652,6 +747,9 @@ EXPORT_SYMBOL(drm_sched_job_arm);
> */
> void drm_sched_job_cleanup(struct drm_sched_job *job)
> {
> + struct dma_fence *fence;
> + unsigned long index;
> +
> if (kref_read(&job->s_fence->finished.refcount)) {
> /* drm_sched_job_arm() has been called */
> dma_fence_put(&job->s_fence->finished);
> @@ -661,6 +759,12 @@ void drm_sched_job_cleanup(struct drm_sched_job *job)
> }
>
> 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 83afc3aa8e2f..a47946f904b6 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 +201,17 @@ 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_add_dependency() and
> + * drm_sched_job_add_implicit_dependencies().
> + */
> + 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 +234,15 @@ 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_add_dependency() and
> + * drm_sched_job_add_implicit_dependencies() this can be ommitted and
> + * left as NULL.
> */
> struct dma_fence *(*dependency)(struct drm_sched_job *sched_job,
> struct drm_sched_entity *s_entity);
> @@ -349,6 +369,13 @@ 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_add_dependency(struct drm_sched_job *job,
> + struct dma_fence *fence);
> +int drm_sched_job_add_implicit_dependencies(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);