[PATCH 18/21] drm/amdgpu: add framework for HW specific priority settings v4

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Am 07.03.2017 um 02:10 schrieb Andres Rodriguez:
> Add an initial framework for changing the HW priorities of rings. The
> framework allows requesting priority changes for the lifetime of an
> amdgpu_job. After the job completes the priority will decay to the next
> lowest priority for which a request is still valid.
>
> A new ring function set_priority() can now be populated to take care of
> the HW specific programming sequence for priority changes.
>
> v2: set priority before emitting IB, and take a ref on amdgpu_job
> v3: use AMD_SCHED_PRIORITY_* instead of AMDGPU_CTX_PRIORITY_*
> v4: plug amdgpu_ring_restore_priority_cb into amdgpu_job_free_cb
> v5: use atomic for tracking job priorities instead of last_job
>
> Signed-off-by: Andres Rodriguez <andresx7 at gmail.com>

Two more nit picks and one real problem below.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_job.c       |  8 +++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c      | 82 +++++++++++++++++++++++++++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h      | 15 +++++
>   drivers/gpu/drm/amd/scheduler/gpu_scheduler.h |  7 +++
>   4 files changed, 112 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> index 86a1242..bd6fa0f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> @@ -88,20 +88,21 @@ void amdgpu_job_free_resources(struct amdgpu_job *job)
>   	f = job->base.s_fence ? &job->base.s_fence->finished : job->fence;
>   
>   	for (i = 0; i < job->num_ibs; ++i)
>   		amdgpu_ib_free(job->adev, &job->ibs[i], f);
>   }
>   
>   static void amdgpu_job_free_cb(struct amd_sched_job *s_job)
>   {
>   	struct amdgpu_job *job = container_of(s_job, struct amdgpu_job, base);
>   
> +	amdgpu_ring_restore_priority(job);
>   	dma_fence_put(job->fence);
>   	amdgpu_sync_free(&job->sync);
>   	kfree(job);
>   }
>   
>   void amdgpu_job_free(struct amdgpu_job *job)
>   {
>   	amdgpu_job_free_resources(job);
>   
>   	dma_fence_put(job->fence);
> @@ -162,28 +163,35 @@ static struct dma_fence *amdgpu_job_run(struct amd_sched_job *sched_job)
>   	int r;
>   
>   	if (!sched_job) {
>   		DRM_ERROR("job is null\n");
>   		return NULL;
>   	}
>   	job = to_amdgpu_job(sched_job);
>   
>   	BUG_ON(amdgpu_sync_peek_fence(&job->sync, NULL));
>   
> +	r = amdgpu_ring_elevate_priority(job->ring,
> +					 amd_sched_get_job_priority(&job->base),
> +					 job);
> +	if (r)
> +		DRM_ERROR("Failed to set job priority (%d)\n", r);
> +
>   	trace_amdgpu_sched_run_job(job);
>   	r = amdgpu_ib_schedule(job->ring, job->num_ibs, job->ibs, job, &fence);
>   	if (r)
>   		DRM_ERROR("Error scheduling IBs (%d)\n", r);
>   
>   	/* if gpu reset, hw fence will be replaced here */
>   	dma_fence_put(job->fence);
>   	job->fence = dma_fence_get(fence);
> +
>   	amdgpu_job_free_resources(job);
>   	return fence;
>   }
>   
>   const struct amd_sched_backend_ops amdgpu_sched_ops = {
>   	.dependency = amdgpu_job_dependency,
>   	.run_job = amdgpu_job_run,
>   	.timedout_job = amdgpu_job_timedout,
>   	.free_job = amdgpu_job_free_cb
>   };
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> index d655fa4..d67dc69 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> @@ -193,20 +193,100 @@ void amdgpu_ring_commit(struct amdgpu_ring *ring)
>    */
>   void amdgpu_ring_undo(struct amdgpu_ring *ring)
>   {
>   	ring->wptr = ring->wptr_old;
>   
>   	if (ring->funcs->end_use)
>   		ring->funcs->end_use(ring);
>   }
>   
>   /**
> + * amdgpu_ring_restore_priority - restore a ring's priority
> + *
> + * @job: job which completed execution
> + *
> + * If necessary, restore a ring's priority after a job finishes executing
> + */
> +void amdgpu_ring_restore_priority(struct amdgpu_job *job)

Only a nit pick. But just giving job_priority as parameter directly here 
would bring it in line with how amdgpu_ring_elevate_priority() works.

> +{
> +	int i;
> +	struct amdgpu_ring *ring = job->ring;
> +	enum amd_sched_priority job_priority;
> +
> +	if (!ring->funcs->set_priority)
> +		return;
> +
> +	job_priority = amd_sched_get_job_priority(&job->base);
> +	if (atomic_dec_return(&ring->num_jobs[job_priority]) > 0)
> +		return;
> +
> +	/* no need to restore if the job is already at the lowest priority */
> +	if (job_priority == AMD_SCHED_PRIORITY_NORMAL)
> +		return;
> +
> +	spin_lock(&ring->priority_lock);
> +	/* something higher prio is executing, no need to decay */
> +	if (ring->priority < job_priority)
> +		goto out_unlock;
> +
> +	/* decay priority to the next level with a job available */
> +	for (i = job_priority; i < AMD_SCHED_MAX_PRIORITY; i++) {
> +		if (i == AMD_SCHED_PRIORITY_NORMAL
> +				|| atomic_read(&ring->num_jobs[i])) {
> +			ring->priority = i;
> +			ring->funcs->set_priority(ring, i);
> +			break;
> +		}
> +	}
> +
> +out_unlock:
> +	spin_unlock(&ring->priority_lock);
> +}
> +
> +/**
> + * amdgpu_ring_elevate_priority - change the ring's priority
> + *
> + * @ring: amdgpu_ring structure holding the information
> + * @priority: target priority
> + * @job: priority should remain elevated for the duration of this job
> + *
> + * Use HW specific mechanism's to elevate the ring's priority while @job
> + * is executing. Once @job finishes executing, the ring will reset back
> + * to normal priority.
> + * Returns 0 on success, error otherwise
> + */
> +int amdgpu_ring_elevate_priority(struct amdgpu_ring *ring,
> +				 enum amd_sched_priority priority,
> +				 struct amdgpu_job *job)

As far as I can see the job parameter is superfluous now.

> +{
> +	if (priority < 0 || priority >= AMD_SCHED_MAX_PRIORITY)
> +		return -EINVAL;
> +
> +	if (!ring->funcs->set_priority)
> +		return 0;
> +
> +	atomic_inc(&ring->num_jobs[priority]);
> +
> +	/* lower number means higher priority */
> +	spin_lock(&ring->priority_lock);

Sorry, could be that I incorrectly suggested that. Double checking the 
set_priority callback you need to take the GRBM mutex to set the 
priority. Don't you?

If that's true this would be illegal cause you take a spin lock first 
and then try to grab a mutex which can cause a deadlock.

BTW: Alex, Felix does anybody of hand know why the GRBM lock is a mutex 
in the first place? Sounds scary to schedule while having the hardware 
in a very specific state.

Regards,
Christian.

> +	if (priority >= ring->priority)
> +		goto out_unlock;
> +
> +	ring->priority = priority;
> +	ring->funcs->set_priority(ring, priority);
> +
> +out_unlock:
> +	spin_unlock(&ring->priority_lock);
> +	return 0;
> +}
> +
> +/**
>    * amdgpu_ring_init - init driver ring struct.
>    *
>    * @adev: amdgpu_device pointer
>    * @ring: amdgpu_ring structure holding ring information
>    * @max_ndw: maximum number of dw for ring alloc
>    * @nop: nop packet for this ring
>    *
>    * Initialize the driver information for the selected ring (all asics).
>    * Returns 0 on success, error on failure.
>    */
> @@ -274,20 +354,22 @@ int amdgpu_ring_init(struct amdgpu_device *adev, struct amdgpu_ring *ring,
>   					    &ring->gpu_addr,
>   					    (void **)&ring->ring);
>   		if (r) {
>   			dev_err(adev->dev, "(%d) ring create failed\n", r);
>   			return r;
>   		}
>   		memset((void *)ring->ring, 0, ring->ring_size);
>   	}
>   	ring->ptr_mask = (ring->ring_size / 4) - 1;
>   	ring->max_dw = max_dw;
> +	ring->priority = AMD_SCHED_PRIORITY_NORMAL;
> +	spin_lock_init(&ring->priority_lock);
>   	INIT_LIST_HEAD(&ring->lru_list);
>   	amdgpu_ring_lru_touch(adev, ring);
>   
>   	if (amdgpu_debugfs_ring_init(adev, ring)) {
>   		DRM_ERROR("Failed to register debugfs file for rings !\n");
>   	}
>   	return 0;
>   }
>   
>   /**
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> index b51bdcd..bad40f8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> @@ -17,20 +17,21 @@
>    * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
>    * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
>    * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
>    * OTHER DEALINGS IN THE SOFTWARE.
>    *
>    * Authors: Christian König
>    */
>   #ifndef __AMDGPU_RING_H__
>   #define __AMDGPU_RING_H__
>   
> +#include <drm/amdgpu_drm.h>
>   #include "gpu_scheduler.h"
>   
>   /* max number of rings */
>   #define AMDGPU_MAX_RINGS		16
>   #define AMDGPU_MAX_GFX_RINGS		1
>   #define AMDGPU_MAX_COMPUTE_RINGS	8
>   #define AMDGPU_MAX_VCE_RINGS		3
>   
>   /* some special values for the owner field */
>   #define AMDGPU_FENCE_OWNER_UNDEFINED	((void*)0ul)
> @@ -45,20 +46,21 @@ enum amdgpu_ring_type {
>   	AMDGPU_RING_TYPE_SDMA,
>   	AMDGPU_RING_TYPE_UVD,
>   	AMDGPU_RING_TYPE_VCE,
>   	AMDGPU_RING_TYPE_KIQ
>   };
>   
>   struct amdgpu_device;
>   struct amdgpu_ring;
>   struct amdgpu_ib;
>   struct amdgpu_cs_parser;
> +struct amdgpu_job;
>   
>   /*
>    * Fences.
>    */
>   struct amdgpu_fence_driver {
>   	uint64_t			gpu_addr;
>   	volatile uint32_t		*cpu_addr;
>   	/* sync_seq is protected by ring emission lock */
>   	uint32_t			sync_seq;
>   	atomic_t			last_seq;
> @@ -130,20 +132,23 @@ struct amdgpu_ring_funcs {
>   	void (*pad_ib)(struct amdgpu_ring *ring, struct amdgpu_ib *ib);
>   	unsigned (*init_cond_exec)(struct amdgpu_ring *ring);
>   	void (*patch_cond_exec)(struct amdgpu_ring *ring, unsigned offset);
>   	/* note usage for clock and power gating */
>   	void (*begin_use)(struct amdgpu_ring *ring);
>   	void (*end_use)(struct amdgpu_ring *ring);
>   	void (*emit_switch_buffer) (struct amdgpu_ring *ring);
>   	void (*emit_cntxcntl) (struct amdgpu_ring *ring, uint32_t flags);
>   	void (*emit_rreg)(struct amdgpu_ring *ring, uint32_t reg);
>   	void (*emit_wreg)(struct amdgpu_ring *ring, uint32_t reg, uint32_t val);
> +	/* priority functions */
> +	void (*set_priority) (struct amdgpu_ring *ring,
> +			      enum amd_sched_priority priority);
>   };
>   
>   struct amdgpu_ring {
>   	struct amdgpu_device		*adev;
>   	const struct amdgpu_ring_funcs	*funcs;
>   	struct amdgpu_fence_driver	fence_drv;
>   	struct amd_gpu_scheduler	sched;
>   	struct list_head		lru_list;
>   
>   	struct amdgpu_bo	*ring_obj;
> @@ -164,31 +169,41 @@ struct amdgpu_ring {
>   	struct amdgpu_bo	*mqd_obj;
>   	u32			doorbell_index;
>   	bool			use_doorbell;
>   	unsigned		wptr_offs;
>   	unsigned		fence_offs;
>   	uint64_t		current_ctx;
>   	char			name[16];
>   	unsigned		cond_exe_offs;
>   	u64			cond_exe_gpu_addr;
>   	volatile u32		*cond_exe_cpu_addr;
> +
> +	atomic_t		num_jobs[AMD_SCHED_MAX_PRIORITY];
> +	spinlock_t		priority_lock;
> +	/* protected by priority_lock */
> +	int			priority;
> +
>   #if defined(CONFIG_DEBUG_FS)
>   	struct dentry *ent;
>   #endif
>   };
>   
>   int amdgpu_ring_is_valid_index(struct amdgpu_device *adev,
>   			       int hw_ip, int ring);
>   int amdgpu_ring_alloc(struct amdgpu_ring *ring, unsigned ndw);
>   void amdgpu_ring_insert_nop(struct amdgpu_ring *ring, uint32_t count);
>   void amdgpu_ring_generic_pad_ib(struct amdgpu_ring *ring, struct amdgpu_ib *ib);
>   void amdgpu_ring_commit(struct amdgpu_ring *ring);
>   void amdgpu_ring_undo(struct amdgpu_ring *ring);
> +int amdgpu_ring_elevate_priority(struct amdgpu_ring *ring,
> +				 enum amd_sched_priority priority,
> +				 struct amdgpu_job *job);
> +void amdgpu_ring_restore_priority(struct amdgpu_job *job);
>   int amdgpu_ring_init(struct amdgpu_device *adev, struct amdgpu_ring *ring,
>   		     unsigned ring_size, struct amdgpu_irq_src *irq_src,
>   		     unsigned irq_type);
>   void amdgpu_ring_fini(struct amdgpu_ring *ring);
>   int amdgpu_ring_lru_get(struct amdgpu_device *adev, int hw_ip,
>   			struct amdgpu_ring **ring);
>   void amdgpu_ring_lru_touch(struct amdgpu_device *adev, struct amdgpu_ring *ring);
>   
>   #endif
> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> index 2e458de..5e25674 100644
> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
> @@ -149,11 +149,18 @@ void amd_sched_fence_slab_fini(void);
>   struct amd_sched_fence *amd_sched_fence_create(
>   	struct amd_sched_entity *s_entity, void *owner);
>   void amd_sched_fence_scheduled(struct amd_sched_fence *fence);
>   void amd_sched_fence_finished(struct amd_sched_fence *fence);
>   int amd_sched_job_init(struct amd_sched_job *job,
>   		       struct amd_gpu_scheduler *sched,
>   		       struct amd_sched_entity *entity,
>   		       void *owner);
>   void amd_sched_hw_job_reset(struct amd_gpu_scheduler *sched);
>   void amd_sched_job_recovery(struct amd_gpu_scheduler *sched);
> +
> +static inline enum amd_sched_priority
> +amd_sched_get_job_priority(struct amd_sched_job *job)
> +{
> +	return (job->s_entity->rq - job->sched->sched_rq);
> +}
> +
>   #endif




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