[RFC PATCH 1/3] drm/amdgpu: implement ring init_priority for compute ring

[Luben Tuikov]

On 2020-02-26 3:37 p.m., Nirmoy Das wrote:
> init_priority will set second compute queue(gfx8 and gfx9) of a pipe to high priority
> and 1st queue to normal priority.
> 
> Signed-off-by: Nirmoy Das <nirmoy.das at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h |  1 +
>  drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c    | 14 ++++++++++++++
>  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c    | 13 +++++++++++++
>  3 files changed, 28 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> index 24caff085d00..a109373b9fe8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> @@ -170,6 +170,7 @@ struct amdgpu_ring_funcs {
>  	/* priority functions */
>  	void (*set_priority) (struct amdgpu_ring *ring,
>  			      enum drm_sched_priority priority);
> +	void (*init_priority) (struct amdgpu_ring *ring);
>  	/* Try to soft recover the ring to make the fence signal */
>  	void (*soft_recovery)(struct amdgpu_ring *ring, unsigned vmid);
>  	int (*preempt_ib)(struct amdgpu_ring *ring);
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> index fa245973de12..14bab6e08bd6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> @@ -6334,6 +6334,19 @@ static void gfx_v8_0_ring_set_priority_compute(struct amdgpu_ring *ring,
>  	gfx_v8_0_pipe_reserve_resources(adev, ring, acquire);
>  }
> 
> +static void gfx_v8_0_ring_init_priority_compute(struct amdgpu_ring *ring)

Why two verbs in this function: "init" and "compute"?
Certainly there is no need for "compute".
Just call it

gfx_blah_ring_priority_init()

Putting the object first and the verb last, as is commonly done.

> +{
> +	/* set pipe 0 to normal priority and pipe 1 to high priority*/
> +	if (ring->queue == 1) {
> +		gfx_v8_0_hqd_set_priority(ring->adev, ring, true);
> +		gfx_v8_0_ring_set_pipe_percent(ring, true);
> +	} else {
> +		gfx_v8_0_hqd_set_priority(ring->adev, ring, false);
> +		gfx_v8_0_ring_set_pipe_percent(ring, false);
> +	}
> +
> +}

Again. Notice that the only difference between the two outcomes
of the conditional is the last parameter to both.

So you could write your code like this:

gfx_v8_0_hqd_set_priority(ring->adev, ring, ring->queue == 1);
gfx_v8_0_ring_set_pipe_percent(ring, ring->queue == 1);

Further more if "priority" had to be variable value,
I'd parameterize it in a map (i.e. array) and use
a computed index to index the map in order to retrieve
the variabled "priority". This eliminates if-conditionals.

Note in general that we want less if-conditionals,
in the execution path and more streamline execution.

> +
>  static void gfx_v8_0_ring_emit_fence_compute(struct amdgpu_ring *ring,
>  					     u64 addr, u64 seq,
>  					     unsigned flags)
> @@ -6967,6 +6980,7 @@ static const struct amdgpu_ring_funcs gfx_v8_0_ring_funcs_compute = {
>  	.insert_nop = amdgpu_ring_insert_nop,
>  	.pad_ib = amdgpu_ring_generic_pad_ib,
>  	.set_priority = gfx_v8_0_ring_set_priority_compute,
> +	.init_priority = gfx_v8_0_ring_init_priority_compute,
>  	.emit_wreg = gfx_v8_0_ring_emit_wreg,
>  };
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 1c7a16b91686..0c66743fb6f5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -5143,6 +5143,18 @@ static void gfx_v9_0_ring_set_priority_compute(struct amdgpu_ring *ring,
>  	gfx_v9_0_pipe_reserve_resources(adev, ring, acquire);
>  }
> 
> +static void gfx_v9_0_ring_init_priority_compute(struct amdgpu_ring *ring)

Ditto for this name as per above.

> +{
> +	/* set pipe 0 to normal priority and pipe 1 to high priority*/
> +	if (ring->queue == 1) {
> +		gfx_v9_0_hqd_set_priority(ring->adev, ring, true);
> +		gfx_v9_0_ring_set_pipe_percent(ring, true);
> +	} else {
> +		gfx_v9_0_hqd_set_priority(ring->adev, ring, false);
> +		gfx_v9_0_ring_set_pipe_percent(ring, true);
> +	}
> +}

Note how similar this is to the v8 above?
Those could be made the same and he vX parameterized to
the correct implementation.

For instance, if you parameterize the "gfx_vX_0_hqd_set_priority()"
and "gfx_vX_0_ring_set_pipe_percent()". Then your code becomes,
like this pseudo-code:

ring_init_set_priority(ring)
{
    map = ring->property[ring->version];

    map->hqd_priority_set(ring->adev, ring, ring->queue == 1);
    map->ring_pipe_percent_set(ring, ring->queue == 1);
}

Regards,
Luben


> +
>  static void gfx_v9_0_ring_set_wptr_compute(struct amdgpu_ring *ring)
>  {
>  	struct amdgpu_device *adev = ring->adev;
> @@ -6514,6 +6526,7 @@ static const struct amdgpu_ring_funcs gfx_v9_0_ring_funcs_compute = {
>  	.insert_nop = amdgpu_ring_insert_nop,
>  	.pad_ib = amdgpu_ring_generic_pad_ib,
>  	.set_priority = gfx_v9_0_ring_set_priority_compute,
> +	.init_priority = gfx_v9_0_ring_init_priority_compute,
>  	.emit_wreg = gfx_v9_0_ring_emit_wreg,
>  	.emit_reg_wait = gfx_v9_0_ring_emit_reg_wait,
>  	.emit_reg_write_reg_wait = gfx_v9_0_ring_emit_reg_write_reg_wait,
> --
> 2.25.0
> 
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