From df6bb8562e79971beb966789e4cbbb2b35fcc9d9 Mon Sep 17 00:00:00 2001
From: TheTurtle <geoster3d@gmail.com>
Date: Mon, 9 Mar 2026 17:46:51 +0200
Subject: [PATCH] renderer_vulkan: Force subgroup size to 64 when possible
 (#4111)

---
 src/video_core/renderer_vulkan/vk_compute_pipeline.cpp | 4 ++++
 src/video_core/renderer_vulkan/vk_instance.cpp         | 7 +++++--
 src/video_core/renderer_vulkan/vk_instance.h           | 7 +++++++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/video_core/renderer_vulkan/vk_compute_pipeline.cpp b/src/video_core/renderer_vulkan/vk_compute_pipeline.cpp
index 35eda86da..eecd416d1 100644
--- a/src/video_core/renderer_vulkan/vk_compute_pipeline.cpp
+++ b/src/video_core/renderer_vulkan/vk_compute_pipeline.cpp
@@ -21,7 +21,11 @@ ComputePipeline::ComputePipeline(const Instance& instance, Scheduler& scheduler,
     info = &info_;
     const auto debug_str = GetDebugString();
 
+    const vk::PipelineShaderStageRequiredSubgroupSizeCreateInfo subgroup_size_ci = {
+        .requiredSubgroupSize = 64,
+    };
     const vk::PipelineShaderStageCreateInfo shader_ci = {
+        .pNext = instance.IsSubgroupSize64Supported() ? &subgroup_size_ci : nullptr,
         .stage = vk::ShaderStageFlagBits::eCompute,
         .module = module,
         .pName = "main",
diff --git a/src/video_core/renderer_vulkan/vk_instance.cpp b/src/video_core/renderer_vulkan/vk_instance.cpp
index 44aa79d98..6898df97a 100644
--- a/src/video_core/renderer_vulkan/vk_instance.cpp
+++ b/src/video_core/renderer_vulkan/vk_instance.cpp
@@ -220,9 +220,11 @@ bool Instance::CreateDevice() {
 
     const vk::StructureChain properties_chain = physical_device.getProperties2<
         vk::PhysicalDeviceProperties2, vk::PhysicalDeviceVulkan11Properties,
-        vk::PhysicalDeviceVulkan12Properties, vk::PhysicalDevicePushDescriptorPropertiesKHR>();
+        vk::PhysicalDeviceVulkan12Properties, vk::PhysicalDeviceVulkan13Properties,
+        vk::PhysicalDevicePushDescriptorPropertiesKHR>();
     vk11_props = properties_chain.get<vk::PhysicalDeviceVulkan11Properties>();
     vk12_props = properties_chain.get<vk::PhysicalDeviceVulkan12Properties>();
+    vk13_props = properties_chain.get<vk::PhysicalDeviceVulkan13Properties>();
     push_descriptor_props = properties_chain.get<vk::PhysicalDevicePushDescriptorPropertiesKHR>();
     LOG_INFO(Render_Vulkan, "Physical device subgroup size {}", vk11_props.subgroupSize);
 
@@ -367,7 +369,7 @@ bool Instance::CreateDevice() {
         feature_chain.get<vk::PhysicalDevicePrimitiveTopologyListRestartFeaturesEXT>();
     const auto vk11_features = feature_chain.get<vk::PhysicalDeviceVulkan11Features>();
     vk12_features = feature_chain.get<vk::PhysicalDeviceVulkan12Features>();
-    const auto vk13_features = feature_chain.get<vk::PhysicalDeviceVulkan13Features>();
+    vk13_features = feature_chain.get<vk::PhysicalDeviceVulkan13Features>();
     vk::StructureChain device_chain = {
         vk::DeviceCreateInfo{
             .queueCreateInfoCount = 1u,
@@ -429,6 +431,7 @@ bool Instance::CreateDevice() {
         vk::PhysicalDeviceVulkan13Features{
             .robustImageAccess = vk13_features.robustImageAccess,
             .shaderDemoteToHelperInvocation = vk13_features.shaderDemoteToHelperInvocation,
+            .subgroupSizeControl = vk13_features.subgroupSizeControl,
             .synchronization2 = vk13_features.synchronization2,
             .dynamicRendering = vk13_features.dynamicRendering,
             .maintenance4 = vk13_features.maintenance4,
diff --git a/src/video_core/renderer_vulkan/vk_instance.h b/src/video_core/renderer_vulkan/vk_instance.h
index 8975669bb..7a8a906d5 100644
--- a/src/video_core/renderer_vulkan/vk_instance.h
+++ b/src/video_core/renderer_vulkan/vk_instance.h
@@ -233,6 +233,11 @@ public:
         return vk12_features.shaderSharedInt64Atomics;
     }
 
+    /// Returns true if the subgroup size can be set to match guest subgroup size
+    bool IsSubgroupSize64Supported() const {
+        return vk13_features.subgroupSizeControl && vk13_props.maxSubgroupSize >= 64;
+    }
+
     /// Returns true when VK_KHR_workgroup_memory_explicit_layout is supported.
     bool IsWorkgroupMemoryExplicitLayoutSupported() const {
         return workgroup_memory_explicit_layout &&
@@ -455,9 +460,11 @@ private:
     vk::PhysicalDeviceMemoryProperties memory_properties;
     vk::PhysicalDeviceVulkan11Properties vk11_props;
     vk::PhysicalDeviceVulkan12Properties vk12_props;
+    vk::PhysicalDeviceVulkan13Properties vk13_props;
     vk::PhysicalDevicePushDescriptorPropertiesKHR push_descriptor_props;
     vk::PhysicalDeviceFeatures features;
     vk::PhysicalDeviceVulkan12Features vk12_features;
+    vk::PhysicalDeviceVulkan13Features vk13_features;
     vk::PhysicalDevicePortabilitySubsetFeaturesKHR portability_features;
     vk::PhysicalDeviceExtendedDynamicState3FeaturesEXT dynamic_state_3_features;
     vk::PhysicalDeviceRobustness2FeaturesEXT robustness2_features;