From c01459347405591446d50858d7b075d617a58be9 Mon Sep 17 00:00:00 2001
From: Takoroka <137927095+Takoroka@users.noreply.github.com>
Date: Thu, 29 Oct 2026 01:26:52 -0400
Subject: video_core: cheaper small GPU reads, buffer usage tracking and
 compute uniforms

- MemoryManager::ReadBlockUnsafe reads within one 4 KiB page through a
  single translation (as Read<T> does) instead of the page walk:
  texture and sampler descriptors, several per draw (2.6% -> 0.1% of
  title 1's GPU thread).
- UsageTracker skips ranges it tracked just before (until Reset): draws
  bind the same multi-megabyte storage buffers again and again, and
  each Track wrote a word per 4 KiB (2.0% -> 0.7%).
- Small compute uniform buffers the GPU has not written are streamed,
  as graphics ones are; synchronizing them re-protected pages an inline
  upload had just unprotected, two VirtualProtect calls per dispatch
  (1.9% -> 0.7%, page protection 3.2% -> 2.3%).
---
 src/video_core/buffer_cache/usage_tracker.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'src/video_core/buffer_cache/usage_tracker.h')

diff --git a/src/video_core/buffer_cache/usage_tracker.h b/src/video_core/buffer_cache/usage_tracker.h
index 6f84e463e3..3e2da8bc0b 100644
--- a/src/video_core/buffer_cache/usage_tracker.h
+++ b/src/video_core/buffer_cache/usage_tracker.h
@@ -6,6 +6,10 @@
 
 #pragma once
 
+#include <array>
+#include <utility>
+#include <vector>
+
 #include "common/alignment.h"
 #include "common/common_types.h"
 
@@ -24,9 +28,19 @@ public:
 
     void Reset() noexcept {
         std::ranges::fill(pages, 0ULL);
+        recent.fill({~u64{0}, 0});
     }
 
     void Track(u64 offset, u64 size) noexcept {
+        // Tracking is idempotent until Reset: skip ranges tracked just before. Draws bind the
+        // same (often multi-megabyte) storage buffers again and again, and each Track wrote a
+        // word per 4 KiB of the range.
+        for (const auto& [recent_offset, recent_size] : recent) {
+            if (recent_offset == offset && recent_size == size) {
+                return;
+            }
+        }
+        recent[recent_cursor++ % recent.size()] = {offset, size};
         const size_t page = offset >> BUFFER_PAGE_SHIFT;
         const size_t page_end = (offset + size) >> BUFFER_PAGE_SHIFT;
         if (page_end < page || page_end >= pages.size()) {
@@ -83,6 +97,9 @@ private:
 
 private:
     std::vector<u64> pages;
+    /// Ranges tracked last, (offset, size).
+    std::array<std::pair<u64, u64>, 4> recent{{{~u64{0}, 0}, {~u64{0}, 0}, {~u64{0}, 0}, {~u64{0}, 0}}};
+    size_t recent_cursor{};
 };
 
 } // namespace VideoCommon
-- 
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