vulkan: bind memory to sparse terrain arrays layer by layer

The written part of Mario Kart World's sparse terrain arrays is small:
13-26% of their blocks. The two 1.45 GB ASTC arrays were backed in full
on the host, and the two 5.8 GB BC6H arrays, too large to back, stayed
unbacked, so what the game streamed into them never showed.

A color array of 32 MiB or more lying in one sparse region, in a format
uploaded layer by layer (huge ASTC arrays decoded on the GPU, or formats
sampled as they are), is now a sparse resident image (SparseLayers).
When it is refreshed, the layers written since (or, for a new image,
the layers any of whose blocks was written) get device memory bound
with vkQueueBindSparse (under the submit lock, waited on, as the
multi-range buffer cache does) and only those layers are uploaded.
Unwritten layers read zero. One image binds at most 768 MiB (384 MiB on
GPUs with less than 7 GiB); rendering into one binds all its layers.

Mario Kart World, 180 s: the ASTC arrays hold 1.4 MiB per written layer,
four BC6H layers (341 MiB) now have their data, device memory in use
4.8-5.0 GB instead of 6.0-7.1 GB with the texture cache below its
collection threshold, 16.8-17.2 ms average frames, peak working set
13.4 GB.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/video_core/texture_cache/image_base.h b/src/video_core/texture_cache/image_base.h
index cfb839d17e..04254fb417 100644
--- a/src/video_core/texture_cache/image_base.h
+++ b/src/video_core/texture_cache/image_base.h
@@ -53,6 +53,9 @@ enum class ImageFlagBits : u32 {
     /// Over Switch 2 sparse blocks nobody wrote: all zeros, so the host image has no memory
     /// (Unbacked) until the first write, which makes a backed image replace it.
     UnwrittenSparse = 1 << 21,
+    /// A large array over Switch 2 sparse blocks: unbacked, each layer gets device memory when
+    /// something is written to it (Image::BindLayers) and only those layers are uploaded.
+    SparseLayers = 1 << 22,
 };
 DECLARE_ENUM_FLAG_OPERATORS(ImageFlagBits)