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vulkan: disable coopmat1 flash attention on Nvidia Turing #19290

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Merged
0cc4m merged 1 commit into from
Feb 3, 2026
Merged

vulkan: disable coopmat1 flash attention on Nvidia Turing #19290

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24 changes: 23 additions & 1 deletion ggml/src/ggml-vulkan/ggml-vulkan.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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) {
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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);
Expand Down
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