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vulkan: Set k_load_shmem to false when K is too large (#19301)

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Jeff Bolz 2026-02-05 01:48:33 -06:00 committed by GitHub
parent c342c3b93d
commit 3409ab842d
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1 changed files with 4 additions and 3 deletions
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ggml/src/ggml-vulkan/ggml-vulkan.cpp
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@ -3204,9 +3204,10 @@ static void ggml_vk_load_shaders(vk_device& device) {
const uint32_t D_lsb = D ^ (D & (D-1));
uint32_t D_split = std::min(std::min(device->subgroup_size, 8u), D_lsb / 4);
// Nvidia prefers shared memory use to load large tiles of K
// Nvidia prefers shared memory use to load large tiles of K.
// Switch to loading from global memory when it would use too much shared memory.
// AMD prefers loading K directly from global memory
const uint32_t k_load_shmem = device->vendor_id == VK_VENDOR_ID_NVIDIA ? 1 : 0;
const uint32_t k_load_shmem = device->vendor_id == VK_VENDOR_ID_NVIDIA && hsk < 256 ? 1 : 0;
return {wg_size, rows_cols[0], rows_cols[1], hsk, hsv, clamp, D_split, device->subgroup_size, k_load_shmem};
};
@ -8412,7 +8413,7 @@ static bool ggml_vk_flash_attn_coopmat_shmem_support(const vk_device& device, co
const uint32_t sfshstride = (hsk <= 128) ? (Br + 8) : Br;
const uint32_t sfsh = Bc * sfshstride * acctype;
const bool k_load_shmem = device->vendor_id == VK_VENDOR_ID_NVIDIA;
const bool k_load_shmem = device->vendor_id == VK_VENDOR_ID_NVIDIA && hsk < 256;
const uint32_t kshstride = (k_load_shmem ? hsk_pad : MatBr) / 4 + 2;
const uint32_t vsh_stride = MatBc / 4 * row_split;
const uint32_t ksh = ((kshstride >= vsh_stride) ? (Bc * kshstride) : (Bc * vsh_stride)) * f16vec4;