On Sun, Jun 2, 2019 at 12:32 PM Alex Smith <asm...@feralinteractive.com> wrote:
>
> Put the uncached GTT type at a higher index than the visible VRAM type,
> rather than having GTT first.
>
> When we don't have dedicated VRAM, we don't have a non-visible VRAM
> type, and the property flags for GTT and visible VRAM are identical.
> According to the spec, for types with identical flags, we should give
> the one with better performance a lower index.
>
> Previously, apps which follow the spec guidance for choosing a memory
> type would have picked the GTT type in preference to visible VRAM (all
> Feral games will do this), and end up with lower performance.
>
> On a Ryzen 5 2500U laptop (Raven Ridge), this improves average FPS in
> the Rise of the Tomb Raider benchmark by up to ~30%. Tested a couple of
> other (Feral) games and saw similar improvement on those as well.
>
> Signed-off-by: Alex Smith <asm...@feralinteractive.com>
> ---
> I noticed that the memory types advertised on my Raven laptop looked a
> bit odd so played around with it and found this. I'm not sure if it is
> actually expected that the performance difference between visible VRAM
> and GTT is so large, seeing as it's not dedicated VRAM, but the results
> are clear (and consistent, tested multiple times).
AFAIU it is still using different memory paths, with GTT using
different pagetables (those from the CPU I believe on APUs) and
possible CPU snooping.
Main risk here seems applications pushing out driver internal stuff
(descriptor sets etc.) from "VRAM", posssibly hitting perf elsewhere.
That said,
Reviewed-by: Bas Nieuwenhuizen <b...@basnieuwenhuizen.nl>
> ---
> src/amd/vulkan/radv_device.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/src/amd/vulkan/radv_device.c b/src/amd/vulkan/radv_device.c
> index 3cf050ed220..d36ee226ebd 100644
> --- a/src/amd/vulkan/radv_device.c
> +++ b/src/amd/vulkan/radv_device.c
> @@ -171,12 +171,11 @@ radv_physical_device_init_mem_types(struct
> radv_physical_device *device)
> .heapIndex = vram_index,
> };
> }
> - if (gart_index >= 0) {
> + if (gart_index >= 0 && device->rad_info.has_dedicated_vram) {
> device->mem_type_indices[type_count] =
> RADV_MEM_TYPE_GTT_WRITE_COMBINE;
> device->memory_properties.memoryTypes[type_count++] =
> (VkMemoryType) {
> .propertyFlags = VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT |
> - VK_MEMORY_PROPERTY_HOST_COHERENT_BIT |
> - (device->rad_info.has_dedicated_vram ? 0 :
> VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT),
> + VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
> .heapIndex = gart_index,
> };
> }
> @@ -189,6 +188,19 @@ radv_physical_device_init_mem_types(struct
> radv_physical_device *device)
> .heapIndex = visible_vram_index,
> };
> }
> + if (gart_index >= 0 && !device->rad_info.has_dedicated_vram) {
> + /* Put GTT after visible VRAM for GPUs without dedicated VRAM
> + * as they have identical property flags, and according to the
> + * spec, for types with identical flags, the one with greater
> + * performance must be given a lower index. */
> + device->mem_type_indices[type_count] =
> RADV_MEM_TYPE_GTT_WRITE_COMBINE;
> + device->memory_properties.memoryTypes[type_count++] =
> (VkMemoryType) {
> + .propertyFlags = VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT |
> + VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT |
> + VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
> + .heapIndex = gart_index,
> + };
> + }
> if (gart_index >= 0) {
> device->mem_type_indices[type_count] =
> RADV_MEM_TYPE_GTT_CACHED;
> device->memory_properties.memoryTypes[type_count++] =
> (VkMemoryType) {
> --
> 2.21.0
>
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