Mesa (master): radv/winsys: always allow GTT placements on APUs

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Module: Mesa
Branch: master
Commit: 28c227c7ca33669d8857f810c23a21a67d53d571
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=28c227c7ca33669d8857f810c23a21a67d53d571

Author: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Date:   Thu Apr 30 20:47:46 2020 +0200

radv/winsys: always allow GTT placements on APUs

When the VRAM size is small and the preferred heap only VRAM,
the kernel tries to always honor the requested heap and it does
a ton of evictions which is a disaster for performance.

On APUs, VRAM and GTT have similar performance, so allow the
kernel to choose the best placement (GTT or VRAM) itself.

This gives a huge performance boost with Doom Eternal on RAVEN.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5665>

---

 src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c b/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c
index 5afb274f1e6..2d153873bfd 100644
--- a/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c
+++ b/src/amd/vulkan/winsys/amdgpu/radv_amdgpu_bo.c
@@ -379,8 +379,19 @@ radv_amdgpu_winsys_bo_create(struct radeon_winsys *_ws,
 	request.alloc_size = size;
 	request.phys_alignment = alignment;
 
-	if (initial_domain & RADEON_DOMAIN_VRAM)
+	if (initial_domain & RADEON_DOMAIN_VRAM) {
 		request.preferred_heap |= AMDGPU_GEM_DOMAIN_VRAM;
+
+		/* Since VRAM and GTT have almost the same performance on
+		 * APUs, we could just set GTT. However, in order to decrease
+		 * GTT(RAM) usage, which is shared with the OS, allow VRAM
+		 * placements too. The idea is not to use VRAM usefully, but
+		 * to use it so that it's not unused and wasted.
+		 */
+		if (!ws->info.has_dedicated_vram)
+			request.preferred_heap |= AMDGPU_GEM_DOMAIN_GTT;
+	}
+
 	if (initial_domain & RADEON_DOMAIN_GTT)
 		request.preferred_heap |= AMDGPU_GEM_DOMAIN_GTT;
 	if (initial_domain & RADEON_DOMAIN_GDS)