[Mesa-dev] [PATCH 10/10] gallium/radeon: lower memory usage during texture transfers

[Nicolai Hähnle]

On 19.05.2016 12:59, Marek Olšák wrote:
> From: Marek Olšák <marek.olsak at amd.com>
>
> This improves throughput by keeping TTM overhead down.
>
> Some piglit tests such as texelFetch and streaming-texture-leak will
> use less memory now.
> ---
>   src/gallium/drivers/radeon/r600_pipe_common.h |  1 +
>   src/gallium/drivers/radeon/r600_texture.c     | 32 +++++++++++++++++++++++----
>   2 files changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h b/src/gallium/drivers/radeon/r600_pipe_common.h
> index ccdf22a..4cdc69a 100644
> --- a/src/gallium/drivers/radeon/r600_pipe_common.h
> +++ b/src/gallium/drivers/radeon/r600_pipe_common.h
> @@ -496,6 +496,7 @@ struct r600_common_context {
>   	/* Misc stats. */
>   	unsigned			num_draw_calls;
>   	unsigned			num_dma_calls;
> +	uint64_t			num_alloc_tex_transfer_bytes;
>
>   	/* Render condition. */
>   	struct r600_atom		render_cond_atom;
> diff --git a/src/gallium/drivers/radeon/r600_texture.c b/src/gallium/drivers/radeon/r600_texture.c
> index 1333a25..1f973cc 100644
> --- a/src/gallium/drivers/radeon/r600_texture.c
> +++ b/src/gallium/drivers/radeon/r600_texture.c
> @@ -1302,9 +1302,11 @@ static bool r600_can_invalidate_texture(struct r600_common_screen *rscreen,
>   						 box->depth);
>   }
>
> -static void r600_texture_invalidate_storage(struct r600_common_screen *rscreen,
> +static void r600_texture_invalidate_storage(struct r600_common_context *rctx,
>   					    struct r600_texture *rtex)
>   {
> +	struct r600_common_screen *rscreen = rctx->screen;
> +
>   	/* There is no point in discarding depth and tiled buffers. */
>   	assert(!rtex->is_depth);
>   	assert(rtex->surface.level[0].mode == RADEON_SURF_MODE_LINEAR_ALIGNED);
> @@ -1319,6 +1321,8 @@ static void r600_texture_invalidate_storage(struct r600_common_screen *rscreen,
>
>   	r600_dirty_all_framebuffer_states(rscreen);
>   	p_atomic_inc(&rscreen->dirty_tex_descriptor_counter);
> +
> +	rctx->num_alloc_tex_transfer_bytes += rtex->size;
>   }
>
>   static void *r600_texture_transfer_map(struct pipe_context *ctx,
> @@ -1378,8 +1382,7 @@ static void *r600_texture_transfer_map(struct pipe_context *ctx,
>   			/* It's busy. */
>   			if (r600_can_invalidate_texture(rctx->screen, rtex,
>   							usage, box))
> -				r600_texture_invalidate_storage(rctx->screen,
> -								rtex);
> +				r600_texture_invalidate_storage(rctx, rtex);
>   			else
>   				use_staging_texture = true;
>   		}
> @@ -1499,6 +1502,7 @@ static void *r600_texture_transfer_map(struct pipe_context *ctx,
>   static void r600_texture_transfer_unmap(struct pipe_context *ctx,
>   					struct pipe_transfer* transfer)
>   {
> +	struct r600_common_context *rctx = (struct r600_common_context*)ctx;
>   	struct r600_transfer *rtransfer = (struct r600_transfer*)transfer;
>   	struct pipe_resource *texture = transfer->resource;
>   	struct r600_texture *rtex = (struct r600_texture*)texture;
> @@ -1514,8 +1518,28 @@ static void r600_texture_transfer_unmap(struct pipe_context *ctx,
>   		}
>   	}
>
> -	if (rtransfer->staging)
> +	if (rtransfer->staging) {
> +		rctx->num_alloc_tex_transfer_bytes += rtransfer->staging->buf->size;
>   		pipe_resource_reference((struct pipe_resource**)&rtransfer->staging, NULL);
> +	}
> +
> +	/* Heuristic for {upload, draw, upload, draw, ..}:
> +	 *
> +	 * Flush the gfx IB if we've allocated too much texture storage.
> +	 *
> +	 * The idea is that we don't want to build IBs that use too much
> +	 * memory and put pressure on the kernel memory manager and we also
> +	 * want to make temporary and invalidated buffers go idle ASAP to
> +	 * decrease the total memory usage or make them reusable. The memory
> +	 * usage will be slightly higher than given here because of the buffer
> +	 * cache in the winsys.
> +	 *
> +	 * The result is that the kernel memory manager is never a bottleneck.
> +	 */
> +	if (rctx->num_alloc_tex_transfer_bytes > rctx->screen->info.vram_size / 4) {
> +		rctx->gfx.flush(rctx, RADEON_FLUSH_ASYNC, NULL);
> +		rctx->num_alloc_tex_transfer_bytes = 0;
> +	}

As far as I understand, the invalidated textures live in GTT. Because of 
that, I think the "measuring stick" should be GTT size instead of VRAM size.

Nicolai

>
>   	FREE(transfer);
>   }
>