From: Ruben Ortlam <redacted>
Date: Tue, 3 Feb 2026 16:37:32 +0000 (+0100)
Subject: vulkan: disable coopmat1 fa on Nvidia Turing (llama/19290)
X-Git-Tag: v0.9.7~59
X-Git-Url: https://git.djapps.eu/?a=commitdiff_plain;h=fda01974f322c1bdf53cd01199f2500f17586d8e;p=pkg%2Fggml%2Fsources%2Fggml

vulkan: disable coopmat1 fa on Nvidia Turing (llama/19290)
---

diff --git a/src/ggml-vulkan/ggml-vulkan.cpp b/src/ggml-vulkan/ggml-vulkan.cpp
index a99375c0..cb7fa2c9 100644
--- a/src/ggml-vulkan/ggml-vulkan.cpp
+++ b/src/ggml-vulkan/ggml-vulkan.cpp
@@ -254,6 +254,7 @@ enum vk_device_architecture {
     AMD_RDNA3,
     INTEL_XE2,
     NVIDIA_PRE_TURING,
+    NVIDIA_TURING,
 };
 
 static vk_device_architecture get_device_architecture(const vk::PhysicalDevice& device) {
@@ -336,18 +337,34 @@ static vk_device_architecture get_device_architecture(const vk::PhysicalDevice&
         const std::vector<vk::ExtensionProperties> ext_props = device.enumerateDeviceExtensionProperties();
 
         bool cooperative_matrix = false;
+        bool sm_builtins = false;
 
         // Detect "pre-turing" based on lack of coopmat support.
         for (const auto& properties : ext_props) {
             if (strcmp("VK_KHR_cooperative_matrix", properties.extensionName) == 0) {
                 cooperative_matrix = true;
-                break;
+            } else if (strcmp("VK_NV_shader_sm_builtins", properties.extensionName) == 0) {
+                sm_builtins = true;
             }
         }
 
         if (!cooperative_matrix) {
             return vk_device_architecture::NVIDIA_PRE_TURING;
         }
+
+        if (sm_builtins) {
+            vk::PhysicalDeviceProperties2 props2;
+            vk::PhysicalDeviceShaderSMBuiltinsPropertiesNV sm_props;
+
+            props2.pNext = &sm_props;
+
+            device.getProperties2(&props2);
+
+            // Turing has 32, following architectures have 48
+            if (sm_props.shaderWarpsPerSM == 32) {
+                return vk_device_architecture::NVIDIA_TURING;
+            }
+        }
     }
     return vk_device_architecture::OTHER;
 }
@@ -8460,6 +8477,11 @@ static void ggml_vk_flash_attn(ggml_backend_vk_context * ctx, vk_context& subctx
     FaCodePath path = ctx->device->coopmat2 ? FA_COOPMAT2 :
                       ctx->device->coopmat1_fa_support ? FA_COOPMAT1 : FA_SCALAR;
 
+    if (path == FA_COOPMAT1 && ctx->device->architecture == vk_device_architecture::NVIDIA_TURING) {
+        // Nvidia compiler bug, see https://github.com/ggml-org/llama.cpp/pull/19075#issuecomment-3820716090
+        path = FA_SCALAR;
+    }
+
     if (path == FA_COOPMAT1) {
         const bool coopmat_shape_supported = (dst->op_params[3] == GGML_PREC_F32 && ctx->device->coopmat_support_16x16x16_f32acc) ||
                                              (dst->op_params[3] != GGML_PREC_F32 && ctx->device->coopmat_support_16x16x16_f16acc);