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llama.cpp
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vulkan: Fix data races in coopmat1 mul_mat(_id) (#20084) 

* vulkan: Fix data races in coopmat1 mul_mat(_id)

Add barriers between coopmat store and regular loads. We sort of got away with
this because it was the same subgroup accessing the values, but it's still a
race and may not work.

* switch to subgroup control barriers
This commit is contained in:
Jeff Bolz 2026-03-08 06:33:48 -05:00 committed by GitHub
parent a976ff081b
commit cd18a50ea5
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1 changed files with 6 additions and 0 deletions
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6
ggml/src/ggml-vulkan/vulkan-shaders/mul_mm.comp
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@ -377,6 +377,7 @@ void main() {
[[unroll]] for (uint cm_col = 0; cm_col < cms_per_col; cm_col++) {
coopMatStore(sums[cm_col * cms_per_row + cm_row], coopmat_stage, warp_i * TM * TN, TM, gl_CooperativeMatrixLayoutColumnMajor);
barrier();
[[unroll]] for (uint col = 0; col < TN; col += storestride) {
const uint row_i = dc + cm_col * TN + col + store_c;
if (row_i >= _ne1) break;
@ -387,6 +388,7 @@ void main() {
data_d[row_idx.y * p.batch_stride_d + row_idx.x * p.stride_d + dr + cm_row * TM + store_r] = D_TYPE(coopmat_stage[warp_i * TM * TN + (col + store_c) * TM + store_r]);
}
}
barrier();
}
}
#else
@ -404,18 +406,22 @@ void main() {
// Full coopMat is within bounds, but stride_d is not aligned
coopMatStore(sums[cm_col * cms_per_row + cm_row], coopmat_stage, warp_i * TM * TN, TM, gl_CooperativeMatrixLayoutColumnMajor);
controlBarrier(gl_ScopeSubgroup, gl_ScopeSubgroup, gl_StorageSemanticsShared, gl_SemanticsAcquireRelease);
[[unroll]] for (uint col = 0; col < TN; col += storestride) {
data_d[offsets + (dc + cm_col * TN + col + store_c) * p.stride_d + dr + cm_row * TM + store_r] = D_TYPE(coopmat_stage[warp_i * TM * TN + (col + store_c) * TM + store_r]);
}
controlBarrier(gl_ScopeSubgroup, gl_ScopeSubgroup, gl_StorageSemanticsShared, gl_SemanticsAcquireRelease);
} else if (dr + cm_row * TM < p.M && dc + cm_col * TN < p.N) {
// Partial coopMat is within bounds
coopMatStore(sums[cm_col * cms_per_row + cm_row], coopmat_stage, warp_i * TM * TN, TM, gl_CooperativeMatrixLayoutColumnMajor);
controlBarrier(gl_ScopeSubgroup, gl_ScopeSubgroup, gl_StorageSemanticsShared, gl_SemanticsAcquireRelease);
[[unroll]] for (uint col = 0; col < TN; col += storestride) {
if (dr + cm_row * TM + store_r < p.M && dc + cm_col * TN + col + store_c < p.N) {
data_d[offsets + (dc + cm_col * TN + col + store_c) * p.stride_d + dr + cm_row * TM + store_r] = D_TYPE(coopmat_stage[warp_i * TM * TN + (col + store_c) * TM + store_r]);
}
}
controlBarrier(gl_ScopeSubgroup, gl_ScopeSubgroup, gl_StorageSemanticsShared, gl_SemanticsAcquireRelease);
}
}
}