Skip to content

vulkan: in flash attention, bounds check against nem1 (don't rely on GGML_KQ_MASK_PAD) #16316

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
+27 −12
Open

vulkan: in flash attention, bounds check against nem1 (don't rely on GGML_KQ_MASK_PAD) #16316

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 0 additions & 4 deletions ggml/src/ggml-vulkan/ggml-vulkan.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2608,8 +2608,6 @@ 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);

// mask dim1 is padded to 64, we rely on this to avoid clamping mask loads
GGML_ASSERT((GGML_KQ_MASK_PAD % rows_cols[0]) == 0);
return {wg_size, rows_cols[0], rows_cols[1], hsk, hsv, clamp, D_split};
};

Expand Down Expand Up @@ -7452,8 +7450,6 @@ static void ggml_vk_flash_attn(ggml_backend_vk_context * ctx, vk_context& subctx
if (((HSK | HSV) % 16) != 0 && path == FA_COOPMAT2) {
aligned = false;
}
// mask dim1 is padded to 64, we rely on this to avoid clamping mask loads
GGML_ASSERT((nem1 % GGML_KQ_MASK_PAD) == 0);

bool f32acc = path == FA_SCALAR || dst->op_params[3] == GGML_PREC_F32;

Expand Down
3 changes: 2 additions & 1 deletion ggml/src/ggml-vulkan/vulkan-shaders/flash_attn.comp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -153,12 +153,13 @@ void main() {
}

if ((p.mask_n_head_log2 & MASK_ENABLE_BIT) != 0) {
bool nem1_bounds_check = !(p.gqa_ratio > 1) && (p.nem1 % Br) != 0;

[[unroll]] for (uint32_t idx = 0; idx < Bc * Br; idx += gl_WorkGroupSize.x) {
uint32_t c = (idx + tid) % Bc;
uint32_t r = (idx + tid) / Bc;
if (idx + tid < Bc * Br) {
if (!KV_bounds_check || j * Bc + c < KV) {
if ((!KV_bounds_check || j * Bc + c < KV) && (!nem1_bounds_check || i * Br + r < p.nem1)) {
masksh[c][r] = float(data_m[m_offset + (i * Br + r) * m_stride + (j * Bc + c)]);
} else {
masksh[c][r] = float(0);
Expand Down
4 changes: 3 additions & 1 deletion ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -201,11 +201,13 @@ void main() {
}

if ((p.mask_n_head_log2 & MASK_ENABLE_BIT) != 0) {
bool nem1_bounds_check = !(p.gqa_ratio > 1) && (p.nem1 % Br) != 0;

[[unroll]] for (uint32_t idx = 0; idx < Bc * Br; idx += gl_WorkGroupSize.x) {
uint32_t c = (idx + tid) % Bc;
uint32_t r = (idx + tid) / Bc;
if (idx + tid < Bc * Br || idx + gl_WorkGroupSize.x <= Bc * Br) {
if (!KV_bounds_check || j * Bc + c < KV) {
if ((!KV_bounds_check || j * Bc + c < KV) && (!nem1_bounds_check || i * Br + r < p.nem1)) {
sfsh[c * sfshstride + r] += ACC_TYPE(slope[r] * float(data_m[m_offset + (i * Br + r) * m_stride + (j * Bc + c)]));
}
}
Expand Down
28 changes: 22 additions & 6 deletions ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm2.comp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -154,15 +154,31 @@ void main() {
}

if ((p.mask_n_head_log2 & MASK_ENABLE_BIT) != 0) {
tensorLayoutNV<2, Clamp> tensorLayoutM = createTensorLayoutNV(2, Clamp);
tensorLayoutM = setTensorLayoutDimensionNV(tensorLayoutM, p.nem1, KV);
tensorLayoutM = setTensorLayoutStrideNV(tensorLayoutM, m_stride, 1);
bool nem1_bounds_check = !(p.gqa_ratio > 1) && (p.nem1 % Br) != 0;

coopmat<float16_t, gl_ScopeWorkgroup, Br, Bc, gl_MatrixUseAccumulator> mv;
if (nem1_bounds_check) {
tensorLayoutNV<2, gl_CooperativeMatrixClampModeConstantNV> tensorLayoutM = createTensorLayoutNV(2, gl_CooperativeMatrixClampModeConstantNV);
tensorLayoutM = setTensorLayoutDimensionNV(tensorLayoutM, p.nem1, KV);
tensorLayoutM = setTensorLayoutStrideNV(tensorLayoutM, m_stride, 1);

coopMatLoadTensorNV(mv, data_m, m_offset, sliceTensorLayoutNV(tensorLayoutM, i * Br, Br, j * Bc, Bc));
coopmat<float16_t, gl_ScopeWorkgroup, Br, Bc, gl_MatrixUseAccumulator> mv;

S += slopeMat*coopmat<ACC_TYPE, gl_ScopeWorkgroup, Br, Bc, gl_MatrixUseAccumulator>(mv);
coopMatLoadTensorNV(mv, data_m, m_offset, sliceTensorLayoutNV(tensorLayoutM, i * Br, Br, j * Bc, Bc));

S += slopeMat*coopmat<ACC_TYPE, gl_ScopeWorkgroup, Br, Bc, gl_MatrixUseAccumulator>(mv);
} else {
tensorLayoutNV<2, Clamp> tensorLayoutM = createTensorLayoutNV(2, Clamp);
// Don't clamp against nem1 when GQA is enabled
uint32_t m_height = p.gqa_ratio > 1 ? ~0 : p.nem1;
tensorLayoutM = setTensorLayoutDimensionNV(tensorLayoutM, m_height, KV);
tensorLayoutM = setTensorLayoutStrideNV(tensorLayoutM, m_stride, 1);

coopmat<float16_t, gl_ScopeWorkgroup, Br, Bc, gl_MatrixUseAccumulator> mv;

coopMatLoadTensorNV(mv, data_m, m_offset, sliceTensorLayoutNV(tensorLayoutM, i * Br, Br, j * Bc, Bc));

S += slopeMat*coopmat<ACC_TYPE, gl_ScopeWorkgroup, Br, Bc, gl_MatrixUseAccumulator>(mv);
}
}

// Clear padding elements to -inf, so they don't contribute to rowmax
Expand Down
Loading