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ggml: fix cuda kernel launch configuration for k_compute_batched_ptrs to support large batch #16744

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Merged
merged 4 commits into from
Oct 26, 2025
Merged

ggml: fix cuda kernel launch configuration for k_compute_batched_ptrs to support large batch #16744

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c2cbb16
fix k_compute_batched_ptrs
leejet Oct 23, 2025
e707662
add backend ops test
leejet Oct 23, 2025
96e2320
Update ggml/src/ggml-cuda/ggml-cuda.cu
leejet Oct 24, 2025
1da9854
reduce the batch size
leejet Oct 24, 2025
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11 changes: 9 additions & 2 deletions ggml/src/ggml-cuda/ggml-cuda.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -1957,8 +1957,15 @@ static void ggml_cuda_mul_mat_batched_cublas_impl(ggml_backend_cuda_context & ct

size_t src1_stride_size = sizeof(cuda_t);

dim3 block_dims(ne13, ne12);
k_compute_batched_ptrs<<<1, block_dims, 0, main_stream>>>(
const int threads_x = 32;
const int threads_y = 32;
dim3 block_dims(threads_x, threads_y);

dim3 grid_dims(
(ne13 + threads_x - 1) / threads_x,
(ne12 + threads_y - 1) / threads_y
);
k_compute_batched_ptrs<<<grid_dims, block_dims, 0, main_stream>>>(
src0_ptr, src1_ptr, dst_t,
ptrs_src.get(), ptrs_dst.get(),
ne12, ne13,
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4 changes: 4 additions & 0 deletions tests/test-backend-ops.cpp
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Expand Up @@ -6562,6 +6562,10 @@ static std::vector<std::unique_ptr<test_case>> make_test_cases_eval() {
test_cases.emplace_back(new test_mul_mat(type_a, type_b, 16, 1, 1024, {3, 2}, {1, 1}));
test_cases.emplace_back(new test_mul_mat(type_a, type_b, 16, 8, 1024, {3, 2}, {1, 1}));
test_cases.emplace_back(new test_mul_mat(type_a, type_b, 16, 16, 1024, {3, 2}, {1, 1}));

// test cases with large batch size
test_cases.emplace_back(new test_mul_mat(type_a, type_b, 16, 8, 256, {1024, 2}, {1, 1}));
test_cases.emplace_back(new test_mul_mat(type_a, type_b, 16, 8, 256, {4096, 1}, {1, 1}));
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@slaren slaren Oct 23, 2025

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Wouldn't a batch size of 1024 be enough to test this?

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@leejet leejet Oct 24, 2025

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1024 happens to be the maximum number of threads, so it won’t trigger any issues. I’ve now changed the batch size to 1536, which is smaller than before.

}
}
for (ggml_type type_a : other_types) {
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