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cuda: cap grid.y at 65535 in non-contiguous dequantize/convert kernel… #8

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Merged
visorcraft merged 1 commit into from
Mar 1, 2026
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cuda: cap grid.y at 65535 in non-contiguous dequantize/convert kernel… #8

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64 changes: 32 additions & 32 deletions ggml/src/ggml-cuda/convert.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -16,27 +16,27 @@ static __global__ void dequantize_block(const void * __restrict__ vx, dst_t * __
return;
}

const int64_t i01 = blockIdx.y;

for (int64_t i0203 = blockIdx.z; i0203 < ne0203; i0203 += gridDim.z) {
const uint2 dm = fast_div_modulo((uint32_t)i0203, ne02);
const int64_t i02 = dm.y;
const int64_t i03 = dm.x;

const int64_t ibx0 = i03*s03 + i02*s02 + i01*s01;

const int64_t ib = ibx0 + i00/qk; // block index
const int64_t iqs = (i00%qk)/qr; // quant index
const int64_t iybs = i00 - i00%qk; // y block start index
const int64_t y_offset = qr == 1 ? 1 : qk/2;

// dequantize
float2 v;
dequantize_kernel(vx, ib, iqs, v);

const int64_t iy0 = (i0203*ne01 + i01)*ne00 + iybs + iqs;
y[iy0 + 0] = ggml_cuda_cast<dst_t>(v.x);
y[iy0 + y_offset] = ggml_cuda_cast<dst_t>(v.y);
for (int64_t i01 = blockIdx.y; i01 < ne01; i01 += gridDim.y) {
for (int64_t i0203 = blockIdx.z; i0203 < ne0203; i0203 += gridDim.z) {
const uint2 dm = fast_div_modulo((uint32_t)i0203, ne02);
const int64_t i02 = dm.y;
const int64_t i03 = dm.x;

const int64_t ibx0 = i03*s03 + i02*s02 + i01*s01;

const int64_t ib = ibx0 + i00/qk; // block index
const int64_t iqs = (i00%qk)/qr; // quant index
const int64_t iybs = i00 - i00%qk; // y block start index
const int64_t y_offset = qr == 1 ? 1 : qk/2;

// dequantize
float2 v;
dequantize_kernel(vx, ib, iqs, v);

const int64_t iy0 = (i0203*ne01 + i01)*ne00 + iybs + iqs;
y[iy0 + 0] = ggml_cuda_cast<dst_t>(v.x);
y[iy0 + y_offset] = ggml_cuda_cast<dst_t>(v.y);
}
}
}

Expand Down Expand Up @@ -492,7 +492,7 @@ static void dequantize_block_cuda(const void * vx, dst_t * y,
const int64_t s01, const int64_t s02, const int64_t s03, cudaStream_t stream) {
const int64_t ne0203 = ne02*ne03;
const uint3 ne02_fdv = init_fastdiv_values(ne02);
const dim3 num_blocks((ne00 + 2*CUDA_DEQUANTIZE_BLOCK_SIZE - 1) / (2*CUDA_DEQUANTIZE_BLOCK_SIZE), ne01, (int)std::min(ne0203, (int64_t)65535));
const dim3 num_blocks((ne00 + 2*CUDA_DEQUANTIZE_BLOCK_SIZE - 1) / (2*CUDA_DEQUANTIZE_BLOCK_SIZE), (int)std::min(ne01, (int64_t)65535), (int)std::min(ne0203, (int64_t)65535));
dequantize_block<qk, qr, dequantize_kernel><<<num_blocks, CUDA_DEQUANTIZE_BLOCK_SIZE, 0, stream>>>
(vx, y, ne00, ne01, ne0203, ne02_fdv, s01, s02, s03);
}
Expand Down Expand Up @@ -628,18 +628,18 @@ static __global__ void convert_unary(
return;
}

const int64_t i01 = blockIdx.y;

const src_t * x = (const src_t *) vx;

for (int64_t i0203 = blockIdx.z; i0203 < ne0203; i0203 += gridDim.z) {
const uint2 dm = fast_div_modulo((uint32_t)i0203, ne02);
const int64_t i02 = dm.y;
const int64_t i03 = dm.x;
for (int64_t i01 = blockIdx.y; i01 < ne01; i01 += gridDim.y) {
for (int64_t i0203 = blockIdx.z; i0203 < ne0203; i0203 += gridDim.z) {
const uint2 dm = fast_div_modulo((uint32_t)i0203, ne02);
const int64_t i02 = dm.y;
const int64_t i03 = dm.x;

const int64_t ix = i03*s03 + i02*s02 + i01*s01 + i00;
const int64_t iy = (i0203*ne01 + i01)*ne00 + i00;
y[iy] = ggml_cuda_cast<dst_t>(x[ix]);
const int64_t ix = i03*s03 + i02*s02 + i01*s01 + i00;
const int64_t iy = (i0203*ne01 + i01)*ne00 + i00;
y[iy] = ggml_cuda_cast<dst_t>(x[ix]);
}
}
}

Expand All @@ -649,7 +649,7 @@ static void convert_unary_cuda(const void * vx, dst_t * y,
const int64_t s01, const int64_t s02, const int64_t s03, cudaStream_t stream) {
const int64_t ne0203 = ne02*ne03;
const uint3 ne02_fdv = init_fastdiv_values(ne02);
const dim3 num_blocks((ne00 + CUDA_DEQUANTIZE_BLOCK_SIZE - 1) / CUDA_DEQUANTIZE_BLOCK_SIZE, ne01, (int)std::min(ne0203, (int64_t)65535));
const dim3 num_blocks((ne00 + CUDA_DEQUANTIZE_BLOCK_SIZE - 1) / CUDA_DEQUANTIZE_BLOCK_SIZE, (int)std::min(ne01, (int64_t)65535), (int)std::min(ne0203, (int64_t)65535));
convert_unary<src_t><<<num_blocks, CUDA_DEQUANTIZE_BLOCK_SIZE, 0, stream>>>
(vx, y, ne00, ne01, ne0203, ne02_fdv, s01, s02, s03);
}
Expand Down