From 81ddcd624d729b088c61d33956d1b072a879724c Mon Sep 17 00:00:00 2001 From: lkazarin Date: Wed, 15 Jul 2026 21:59:48 +0200 Subject: [PATCH] vulkan: clamp l_/m_ warptile WM to <= BM (fix wrong matmul on subgroupSize > 64) The l_/m_ warptiles set WM (and WARP) to subgroup_size_8, encoding an implicit WM <= BM invariant. It holds for subgroupSize in {8,16,32,64} but breaks at 128 (Adreno reports subgroupSize=128 under double threadsize): m_warptile gets WM=128 > BM=64, l_warptile gets WM=256 > BM=128. In mul_mm.comp this makes BM/WM fold to 0, buf_a indexing overrun into buf_b, and half the output columns go unwritten -> silently wrong results (test-backend-ops MUL_MAT f16 fails on batched+broadcast+partial-tile shapes; whisper.cpp outputs garbage on GPU). Clamp the tiling WARP for the l_/m_ warptiles to 64. s_warptile keeps the unclamped value (its BLOCK_SIZE is subgroup_size_32 and it needs NUM_WARPS==1). The min is a no-op on subgroupSize <= 64 devices. Fixes #25734 --- ggml/src/ggml-vulkan/ggml-vulkan.cpp | 48 +++++++++++++++++----------- 1 file changed, 30 insertions(+), 18 deletions(-) diff --git a/ggml/src/ggml-vulkan/ggml-vulkan.cpp b/ggml/src/ggml-vulkan/ggml-vulkan.cpp index 3c514930e2df..9df03c841f1c 100644 --- a/ggml/src/ggml-vulkan/ggml-vulkan.cpp +++ b/ggml/src/ggml-vulkan/ggml-vulkan.cpp @@ -3877,11 +3877,23 @@ static void ggml_vk_load_shaders(vk_device& device, vk_pipeline requested) { // some shaders have a minimum subgroup size const uint32_t subgroup_size_8 = std::max(device->subgroup_size, 8u); + // The l_/m_ warptiles encode an implicit invariant WM <= BM: + // l_warptile: BM=128, WM=warp*2 ; m_warptile: BM=64, WM=warp + // Adreno/turnip reports subgroupSize=128 (double threadsize), making both + // degenerate (WM>BM): BM/WM folds to 0 (div-by-zero in mul_mm.comp), buf_a + // indexing runs past its end into buf_b, and half the output columns are + // never written -> silently wrong results. Clamp the tiling WARP for those + // two tiles to 64 (keeps NUM_WARPS*WM*WN == BM*BN and WM<=BM). + // NOTE: s_warptile must keep the unclamped value -- its BLOCK_SIZE is + // subgroup_size_32, and it needs NUM_WARPS==1 to keep its area at BM*BN. + const uint32_t mm_warp_8 = std::min(subgroup_size_8, 64u); const uint32_t subgroup_size_16 = std::max(device->subgroup_size, 16u); const uint32_t subgroup_size_32 = std::max(device->subgroup_size, 32u); const uint32_t mul_mat_subgroup_size = (device->vendor_id == VK_VENDOR_ID_INTEL && device->subgroup_size_control) ? device->subgroup_min_size : device->subgroup_size; const uint32_t mul_mat_subgroup_size_8 = std::max(mul_mat_subgroup_size, 8u); + // same WM<=BM clamp as mm_warp_8, for the mmqid l_/m_ warptiles + const uint32_t mul_mat_mm_warp_8 = std::min(mul_mat_subgroup_size_8, 64u); const uint32_t mul_mat_subgroup_size_16 = std::max(mul_mat_subgroup_size, 16u); const uint32_t mul_mat_subgroup_size_32 = std::max(mul_mat_subgroup_size, 32u); @@ -3964,34 +3976,34 @@ static void ggml_vk_load_shaders(vk_device& device, vk_pipeline requested) { const uint32_t s_warptile_wm = device->subgroup_size == 8 ? 8 : 32; - l_warptile = { 128, 128, 128, 16, subgroup_size_8 * 2, 64, 2, tm_l, tn_l, tk_l, subgroup_size_8 }; - m_warptile = { 128, 64, 64, 16, subgroup_size_8, 32, 2, tm_m, tn_m, tk_m, subgroup_size_8 }; + l_warptile = { 128, 128, 128, 16, mm_warp_8 * 2, 64, 2, tm_l, tn_l, tk_l, mm_warp_8 }; + m_warptile = { 128, 64, 64, 16, mm_warp_8, 32, 2, tm_m, tn_m, tk_m, mm_warp_8 }; s_warptile = { subgroup_size_32, 32, 32, 16, s_warptile_wm, 32, 2, tm_s, tn_s, tk_s, subgroup_size_8 }; - l_warptile_mmq = { 128, 128, 128, 32, subgroup_size_8 * 2, 64, 2, tm_l, tn_l, tk_l, subgroup_size_8 }; - m_warptile_mmq = { 128, 64, 64, 32, subgroup_size_8, 32, 2, tm_m, tn_m, tk_m, subgroup_size_8 }; + l_warptile_mmq = { 128, 128, 128, 32, mm_warp_8 * 2, 64, 2, tm_l, tn_l, tk_l, mm_warp_8 }; + m_warptile_mmq = { 128, 64, 64, 32, mm_warp_8, 32, 2, tm_m, tn_m, tk_m, mm_warp_8 }; s_warptile_mmq = { subgroup_size_32, 32, 32, 32, s_warptile_wm, 32, 2, tm_s, tn_s, tk_s, subgroup_size_8 }; // Integer MMQ has a smaller shared memory profile, but heavier register use - l_warptile_mmq_int = { 128, 128, 128, 32, subgroup_size_8 * 2, 64, 2, 4, 4, 1, subgroup_size_8 }; - m_warptile_mmq_int = { 128, 64, 64, 32, subgroup_size_8, 32, 2, 2, 2, 1, subgroup_size_8 }; + l_warptile_mmq_int = { 128, 128, 128, 32, mm_warp_8 * 2, 64, 2, 4, 4, 1, mm_warp_8 }; + m_warptile_mmq_int = { 128, 64, 64, 32, mm_warp_8, 32, 2, 2, 2, 1, mm_warp_8 }; s_warptile_mmq_int = { subgroup_size_32, 32, 32, 32, s_warptile_wm, 32, 2, 2, 1, 1, subgroup_size_8 }; // K-quants use even more registers, mitigate by setting WMITER to 1 - l_warptile_mmq_int_k = { 128, 128, 128, 32, subgroup_size_8 * 2, 64, 1, 4, 4, 1, subgroup_size_8 }; - m_warptile_mmq_int_k = { 128, 64, 64, 32, subgroup_size_8, 32, 1, 2, 2, 1, subgroup_size_8 }; + l_warptile_mmq_int_k = { 128, 128, 128, 32, mm_warp_8 * 2, 64, 1, 4, 4, 1, mm_warp_8 }; + m_warptile_mmq_int_k = { 128, 64, 64, 32, mm_warp_8, 32, 1, 2, 2, 1, mm_warp_8 }; s_warptile_mmq_int_k = { subgroup_size_32, 32, 32, 32, s_warptile_wm, 32, 1, 2, 1, 1, subgroup_size_8 }; l_warptile_id = { 128, 128, 128, 16, mul_mat_subgroup_size_16 * 2, 64, 2, tm_l, tn_l, tk_l, mul_mat_subgroup_size_16 }; m_warptile_id = { 128, 64, 64, 16, mul_mat_subgroup_size_16, 32, 2, tm_m, tn_m, tk_m, mul_mat_subgroup_size_16 }; s_warptile_id = { mul_mat_subgroup_size_16, 32, 32, 16, s_warptile_wm, 32, 2, tm_s, tn_s, tk_s, mul_mat_subgroup_size_16 }; - l_warptile_mmqid = { 128, 128, 128, 32, mul_mat_subgroup_size_8 * 2, 64, 2, tm_l, tn_l, tk_l, mul_mat_subgroup_size_8 }; - m_warptile_mmqid = { 128, 64, 64, 32, mul_mat_subgroup_size_8, 32, 2, tm_m, tn_m, tk_m, mul_mat_subgroup_size_8 }; + l_warptile_mmqid = { 128, 128, 128, 32, mul_mat_mm_warp_8 * 2, 64, 2, tm_l, tn_l, tk_l, mul_mat_mm_warp_8 }; + m_warptile_mmqid = { 128, 64, 64, 32, mul_mat_mm_warp_8, 32, 2, tm_m, tn_m, tk_m, mul_mat_mm_warp_8 }; s_warptile_mmqid = { mul_mat_subgroup_size_32, 32, 32, 32, s_warptile_wm, 32, 2, tm_s, tn_s, tk_s, mul_mat_subgroup_size_8 }; - l_warptile_mmqid_int = { 128, 128, 128, 32, mul_mat_subgroup_size_8 * 2, 64, 2, 4, 4, 1, mul_mat_subgroup_size_8 }; - m_warptile_mmqid_int = { 128, 64, 64, 32, mul_mat_subgroup_size_8, 32, 2, 2, 2, 1, mul_mat_subgroup_size_8 }; + l_warptile_mmqid_int = { 128, 128, 128, 32, mul_mat_mm_warp_8 * 2, 64, 2, 4, 4, 1, mul_mat_mm_warp_8 }; + m_warptile_mmqid_int = { 128, 64, 64, 32, mul_mat_mm_warp_8, 32, 2, 2, 2, 1, mul_mat_mm_warp_8 }; s_warptile_mmqid_int = { mul_mat_subgroup_size_32, 32, 32, 32, s_warptile_wm, 32, 2, 2, 1, 1, mul_mat_subgroup_size_8 }; l_warptile_mmqid_int_k = { 128, 128, 128, 32, mul_mat_subgroup_size_16 * 2, 64, 1, 4, 4, 1, mul_mat_subgroup_size_16 }; @@ -4004,13 +4016,13 @@ static void ggml_vk_load_shaders(vk_device& device, vk_pipeline requested) { m_warptile_mmqid = m_warptile_mmqid_int = { 256, 64, 64, 32, 16, 16, 2, 2, 2, 1, 16 }; } else if (device->vendor_id == VK_VENDOR_ID_AMD && device->coopmat_support && device->driver_id != vk::DriverId::eAmdProprietary) { // This is intentionally using tx_m values, slight performance increase - l_warptile = { 256, 128, 128, 16, subgroup_size_8, 64, 2, tm_m, tn_m, tk_m, subgroup_size_8 }; - l_warptile_mmq = l_warptile_mmq_int = { 256, 128, 128, 32, subgroup_size_8, 64, 2, tm_m, tn_m, tk_m, subgroup_size_8 }; + l_warptile = { 256, 128, 128, 16, mm_warp_8, 64, 2, tm_m, tn_m, tk_m, mm_warp_8 }; + l_warptile_mmq = l_warptile_mmq_int = { 256, 128, 128, 32, mm_warp_8, 64, 2, tm_m, tn_m, tk_m, mm_warp_8 }; l_warptile_mmq_int_k = { 256, 128, 128, 32, subgroup_size_16, 64, 1, 4, 2, 1, subgroup_size_16 }; } else if (device->vendor_id == VK_VENDOR_ID_INTEL && device->coopmat_support) { // Xe2/Xe3 with coopmat enabled - warptile performance tuning - l_warptile = { 512, 128, 128, 16, subgroup_size_8, 32, 2, tm_m, tn_m, tk_m, subgroup_size_8 }; - l_warptile_mmq = { 512, 128, 128, 32, subgroup_size_8, 32, 2, tm_m, tn_m, tk_m, subgroup_size_8 }; + l_warptile = { 512, 128, 128, 16, mm_warp_8, 32, 2, tm_m, tn_m, tk_m, mm_warp_8 }; + l_warptile_mmq = { 512, 128, 128, 32, mm_warp_8, 32, 2, tm_m, tn_m, tk_m, mm_warp_8 }; } l_mmq_wg_denoms = l_wg_denoms = {128, 128, 1 }; @@ -4854,8 +4866,8 @@ static void ggml_vk_load_shaders(vk_device& device, vk_pipeline requested) { const uint32_t s_warptile_wm = device->subgroup_size == 8 ? 8 : 32; // use scalar tile sizes - l_warptile = { 128, 128, 128, 16, subgroup_size_8 * 2, 64, 2, 4, 4, 1, subgroup_size_8 }; - m_warptile = { 128, 64, 64, 16, subgroup_size_8, 32, 2, 4, 2, 1, subgroup_size_8 }; + l_warptile = { 128, 128, 128, 16, mm_warp_8 * 2, 64, 2, 4, 4, 1, mm_warp_8 }; + m_warptile = { 128, 64, 64, 16, mm_warp_8, 32, 2, 4, 2, 1, mm_warp_8 }; s_warptile = { subgroup_size_32, 32, 32, 16, s_warptile_wm, 32, 2, 2, 2, 1, subgroup_size_8 }; l_wg_denoms = {128, 128, 1 };