From 393a0bd4376a8ecdde079344681a014ec3eb1291 Mon Sep 17 00:00:00 2001 From: Christian König Date: Thu, 5 Nov 2015 12:57:10 +0100 Subject: drm/amdgpu: optimize scheduler fence handling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We only need to wait for jobs to be scheduled when the dependency is from the same scheduler. Signed-off-by: Christian König Reviewed-by: Chunming Zhou --- drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 51 ++++++++++++++++++++------- 1 file changed, 38 insertions(+), 13 deletions(-) (limited to 'drivers/gpu/drm/amd/scheduler/gpu_scheduler.c') diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c index ea30d6ad4c13..b7cd108212c2 100644 --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c @@ -211,6 +211,41 @@ static void amd_sched_entity_wakeup(struct fence *f, struct fence_cb *cb) amd_sched_wakeup(entity->sched); } +static bool amd_sched_entity_add_dependency_cb(struct amd_sched_entity *entity) +{ + struct amd_gpu_scheduler *sched = entity->sched; + struct fence * fence = entity->dependency; + struct amd_sched_fence *s_fence; + + if (fence->context == entity->fence_context) { + /* We can ignore fences from ourself */ + fence_put(entity->dependency); + return false; + } + + s_fence = to_amd_sched_fence(fence); + if (s_fence && s_fence->sched == sched) { + /* Fence is from the same scheduler */ + if (test_bit(AMD_SCHED_FENCE_SCHEDULED_BIT, &fence->flags)) { + /* Ignore it when it is already scheduled */ + fence_put(entity->dependency); + return false; + } + + /* Wait for fence to be scheduled */ + entity->cb.func = amd_sched_entity_wakeup; + list_add_tail(&entity->cb.node, &s_fence->scheduled_cb); + return true; + } + + if (!fence_add_callback(entity->dependency, &entity->cb, + amd_sched_entity_wakeup)) + return true; + + fence_put(entity->dependency); + return false; +} + static struct amd_sched_job * amd_sched_entity_pop_job(struct amd_sched_entity *entity) { @@ -223,20 +258,9 @@ amd_sched_entity_pop_job(struct amd_sched_entity *entity) if (!kfifo_out_peek(&entity->job_queue, &sched_job, sizeof(sched_job))) return NULL; - while ((entity->dependency = sched->ops->dependency(sched_job))) { - - if (entity->dependency->context == entity->fence_context) { - /* We can ignore fences from ourself */ - fence_put(entity->dependency); - continue; - } - - if (fence_add_callback(entity->dependency, &entity->cb, - amd_sched_entity_wakeup)) - fence_put(entity->dependency); - else + while ((entity->dependency = sched->ops->dependency(sched_job))) + if (amd_sched_entity_add_dependency_cb(entity)) return NULL; - } return sched_job; } @@ -400,6 +424,7 @@ static int amd_sched_main(void *param) atomic_inc(&sched->hw_rq_count); fence = sched->ops->run_job(sched_job); + amd_sched_fence_scheduled(s_fence); if (fence) { r = fence_add_callback(fence, &s_fence->cb, amd_sched_process_job); -- cgit v1.2.3 From 3d65193635e122d0783b97cb2202b7f21601037a Mon Sep 17 00:00:00 2001 From: Christian König Date: Thu, 12 Nov 2015 21:10:35 +0100 Subject: drm/amdgpu: move dependency handling out of atomic section v2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This way the driver isn't limited in the dependency handling callback. v2: remove extra check in amd_sched_entity_pop_job() Signed-off-by: Christian König Reviewed-by: Chunming Zhou --- drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 71 +++++++++++++++++---------- 1 file changed, 44 insertions(+), 27 deletions(-) (limited to 'drivers/gpu/drm/amd/scheduler/gpu_scheduler.c') diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c index b7cd108212c2..651129f2ec1d 100644 --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c @@ -30,8 +30,7 @@ #define CREATE_TRACE_POINTS #include "gpu_sched_trace.h" -static struct amd_sched_job * -amd_sched_entity_pop_job(struct amd_sched_entity *entity); +static bool amd_sched_entity_is_ready(struct amd_sched_entity *entity); static void amd_sched_wakeup(struct amd_gpu_scheduler *sched); struct kmem_cache *sched_fence_slab; @@ -64,36 +63,36 @@ static void amd_sched_rq_remove_entity(struct amd_sched_rq *rq, } /** - * Select next job from a specified run queue with round robin policy. - * Return NULL if nothing available. + * Select an entity which could provide a job to run + * + * @rq The run queue to check. + * + * Try to find a ready entity, returns NULL if none found. */ -static struct amd_sched_job * -amd_sched_rq_select_job(struct amd_sched_rq *rq) +static struct amd_sched_entity * +amd_sched_rq_select_entity(struct amd_sched_rq *rq) { struct amd_sched_entity *entity; - struct amd_sched_job *sched_job; spin_lock(&rq->lock); entity = rq->current_entity; if (entity) { list_for_each_entry_continue(entity, &rq->entities, list) { - sched_job = amd_sched_entity_pop_job(entity); - if (sched_job) { + if (amd_sched_entity_is_ready(entity)) { rq->current_entity = entity; spin_unlock(&rq->lock); - return sched_job; + return entity; } } } list_for_each_entry(entity, &rq->entities, list) { - sched_job = amd_sched_entity_pop_job(entity); - if (sched_job) { + if (amd_sched_entity_is_ready(entity)) { rq->current_entity = entity; spin_unlock(&rq->lock); - return sched_job; + return entity; } if (entity == rq->current_entity) @@ -176,6 +175,24 @@ static bool amd_sched_entity_is_idle(struct amd_sched_entity *entity) return false; } +/** + * Check if entity is ready + * + * @entity The pointer to a valid scheduler entity + * + * Return true if entity could provide a job. + */ +static bool amd_sched_entity_is_ready(struct amd_sched_entity *entity) +{ + if (kfifo_is_empty(&entity->job_queue)) + return false; + + if (ACCESS_ONCE(entity->dependency)) + return false; + + return true; +} + /** * Destroy a context entity * @@ -252,9 +269,6 @@ amd_sched_entity_pop_job(struct amd_sched_entity *entity) struct amd_gpu_scheduler *sched = entity->sched; struct amd_sched_job *sched_job; - if (ACCESS_ONCE(entity->dependency)) - return NULL; - if (!kfifo_out_peek(&entity->job_queue, &sched_job, sizeof(sched_job))) return NULL; @@ -328,22 +342,22 @@ static void amd_sched_wakeup(struct amd_gpu_scheduler *sched) } /** - * Select next to run + * Select next entity to process */ -static struct amd_sched_job * -amd_sched_select_job(struct amd_gpu_scheduler *sched) +static struct amd_sched_entity * +amd_sched_select_entity(struct amd_gpu_scheduler *sched) { - struct amd_sched_job *sched_job; + struct amd_sched_entity *entity; if (!amd_sched_ready(sched)) return NULL; /* Kernel run queue has higher priority than normal run queue*/ - sched_job = amd_sched_rq_select_job(&sched->kernel_rq); - if (sched_job == NULL) - sched_job = amd_sched_rq_select_job(&sched->sched_rq); + entity = amd_sched_rq_select_entity(&sched->kernel_rq); + if (entity == NULL) + entity = amd_sched_rq_select_entity(&sched->sched_rq); - return sched_job; + return entity; } static void amd_sched_process_job(struct fence *f, struct fence_cb *cb) @@ -405,13 +419,16 @@ static int amd_sched_main(void *param) unsigned long flags; wait_event_interruptible(sched->wake_up_worker, - kthread_should_stop() || - (sched_job = amd_sched_select_job(sched))); + (entity = amd_sched_select_entity(sched)) || + kthread_should_stop()); + if (!entity) + continue; + + sched_job = amd_sched_entity_pop_job(entity); if (!sched_job) continue; - entity = sched_job->s_entity; s_fence = sched_job->s_fence; if (sched->timeout != MAX_SCHEDULE_TIMEOUT) { -- cgit v1.2.3 From 07df04dfcfe51a45239d056d43cbc09702262c82 Mon Sep 17 00:00:00 2001 From: Nicolai Hähnle Date: Wed, 2 Dec 2015 17:35:12 +0100 Subject: drm/amdgpu: fix race condition in amd_sched_entity_push_job MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit As soon as we leave the spinlock after the job has been added to the job queue, we can no longer rely on the job's data to be available. I have seen a null-pointer dereference due to sched == NULL in amd_sched_wakeup via amd_sched_entity_push_job and amd_sched_ib_submit_kernel_helper. Since the latter initializes sched_job->sched with the address of the ring scheduler, which is guaranteed to be non-NULL, this race appears to be a likely culprit. Signed-off-by: Nicolai Hähnle Bugzilla: https://bugs.freedesktop.org/attachment.cgi?bugid=93079 Reviewed-by: Christian König --- drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/amd/scheduler/gpu_scheduler.c') diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c index 651129f2ec1d..3a4820e863ec 100644 --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c @@ -288,6 +288,7 @@ amd_sched_entity_pop_job(struct amd_sched_entity *entity) */ static bool amd_sched_entity_in(struct amd_sched_job *sched_job) { + struct amd_gpu_scheduler *sched = sched_job->sched; struct amd_sched_entity *entity = sched_job->s_entity; bool added, first = false; @@ -302,7 +303,7 @@ static bool amd_sched_entity_in(struct amd_sched_job *sched_job) /* first job wakes up scheduler */ if (first) - amd_sched_wakeup(sched_job->sched); + amd_sched_wakeup(sched); return added; } @@ -318,9 +319,9 @@ void amd_sched_entity_push_job(struct amd_sched_job *sched_job) { struct amd_sched_entity *entity = sched_job->s_entity; + trace_amd_sched_job(sched_job); wait_event(entity->sched->job_scheduled, amd_sched_entity_in(sched_job)); - trace_amd_sched_job(sched_job); } /** -- cgit v1.2.3