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| author | Mitja Felicijan <mitja.felicijan@gmail.com> | 2026-02-12 20:57:17 +0100 |
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| committer | Mitja Felicijan <mitja.felicijan@gmail.com> | 2026-02-12 20:57:17 +0100 |
| commit | b333b06772c89d96aacb5490d6a219fba7c09cc6 (patch) | |
| tree | 211df60083a5946baa2ed61d33d8121b7e251b06 /llama.cpp/ggml/src/ggml-cuda/quantize.cu | |
| download | llmnpc-b333b06772c89d96aacb5490d6a219fba7c09cc6.tar.gz | |
Engage!
Diffstat (limited to 'llama.cpp/ggml/src/ggml-cuda/quantize.cu')
| -rw-r--r-- | llama.cpp/ggml/src/ggml-cuda/quantize.cu | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/llama.cpp/ggml/src/ggml-cuda/quantize.cu b/llama.cpp/ggml/src/ggml-cuda/quantize.cu new file mode 100644 index 0000000..a8c68e4 --- /dev/null +++ b/llama.cpp/ggml/src/ggml-cuda/quantize.cu @@ -0,0 +1,343 @@ +#include "quantize.cuh" +#include <cstdint> + +__launch_bounds__(CUDA_QUANTIZE_BLOCK_SIZE, 1) +static __global__ void quantize_q8_1( + const float * __restrict__ x, void * __restrict__ vy, + const int64_t ne00, const int64_t s01, const int64_t s02, const int64_t s03, + const int64_t ne0, const uint32_t ne1, const uint3 ne2) { + const int64_t i0 = (int64_t)blockDim.x*blockIdx.x + threadIdx.x; + + if (i0 >= ne0) { + return; + } + + const int64_t i3 = fastdiv(blockIdx.z, ne2); + const int64_t i2 = blockIdx.z - i3*ne2.z; + const int64_t i1 = blockIdx.y; + + const int64_t & i00 = i0; + const int64_t & i01 = i1; + const int64_t & i02 = i2; + const int64_t & i03 = i3; + + const int64_t i_cont = ((i3*ne2.z + i2) * ne1 + i1) * ne0 + i0; + + block_q8_1 * y = (block_q8_1 *) vy; + + const int64_t ib = i_cont / QK8_1; // block index + const int64_t iqs = i_cont % QK8_1; // quant index + + const float xi = i0 < ne00 ? x[i03*s03 + i02*s02 + i01*s01 + i00] : 0.0f; + float amax = fabsf(xi); + float sum = xi; + + amax = warp_reduce_max<QK8_1>(amax); + sum = warp_reduce_sum<QK8_1>(sum); + + const float d = amax / 127.0f; + const int8_t q = amax == 0.0f ? 0 : roundf(xi / d); + + y[ib].qs[iqs] = q; + + if (iqs > 0) { + return; + } + + y[ib].ds = make_half2(d, sum); +} + +__device__ __forceinline__ uint8_t compute_e8m0_scale(float amax) { + if (!(amax > 0.0f)) { + return 0; + } + + // FP4 E2M1: max exponent (unbiased) is 2. + constexpr int FP4_E2M1_EMAX = 2; + + const float e = log2f(amax); + + // "even" -> round-to-nearest integer, ties-to-even + const int e_int = __float2int_rn(e); + + const int shared_exp = e_int - FP4_E2M1_EMAX; + + int biased = shared_exp + 127; + + biased = max(biased, 0); + biased = min(biased, 254); + + return static_cast<uint8_t>(biased); +} + +// quantize values in the format mxfp4 is stored which is interleaved nibbles +// i.e. a block a0-a31 is represented as a0a16,a1a17 ...a15a31 +static __global__ void quantize_mmq_mxfp4(const float * __restrict__ x, + const int32_t * __restrict__ ids, + void * __restrict__ vy, + const int64_t ne00, + const int64_t s01, + const int64_t s02, + const int64_t s03, + const int64_t ne0, + const int ne1, + const int ne2) { + constexpr int vals_per_scale = 32; + constexpr int vals_per_warp = 2 * vals_per_scale; // Each warp processes 2 blocks of 32 = 64 values + + const int warp_id = threadIdx.y; + const int lane_id_32 = threadIdx.x; + + const int nwarps = blockDim.y; + + const int64_t warp_start_offset = (blockIdx.y * nwarps + warp_id) * vals_per_warp; + + if (warp_start_offset >= ne0) { + return; + } + + const int64_t i1 = blockIdx.x; + const int64_t i2 = blockIdx.z % ne2; + const int64_t i3 = blockIdx.z / ne2; + + const int64_t i01 = ids ? ids[i1] : i1; + const int64_t i02 = i2; + const int64_t i03 = i3; + + block_fp4_mmq * y = (block_fp4_mmq *) vy; + + const int64_t block_fp4_mmq_size = 8 * QK_MXFP4; // 256 values + const int64_t ib0 = blockIdx.z * ((int64_t) ne1 * (ne0 / block_fp4_mmq_size)); + const int64_t ib = ib0 + (warp_start_offset / block_fp4_mmq_size) * ne1 + blockIdx.x; + const int64_t quad_idx_in_block = (warp_start_offset % block_fp4_mmq_size) / vals_per_warp; + + const int group_id = lane_id_32 / 4; + const int lane_in_group = lane_id_32 % 4; + const int base = group_id * 2; + char2 * yqs2 = (char2 *) y[ib].qs; + + const int64_t base_pos = i03 * s03 + i02 * s02 + i01 * s01; + + uint8_t scales[2]; + +#pragma unroll + for (int b = 0; b < 2; ++b) { + const int64_t i0 = warp_start_offset + b * vals_per_scale + lane_id_32; + const float xi = (i0 < ne00) ? x[base_pos + i0] : 0.0f; + + float amax = fabsf(xi); +#pragma unroll + for (int mask = 16; mask > 0; mask >>= 1) { + amax = fmaxf(amax, __shfl_xor_sync(0xFFFFFFFF, amax, mask, WARP_SIZE)); + } + + const uint8_t e = compute_e8m0_scale(amax); + scales[b] = e; + const float inv_s = (amax == 0.0f) ? 0.0f : __frcp_rn(ggml_cuda_e8m0_to_fp32(e)); + +#if CUDART_VERSION >= 12080 + const float scaled_val = xi * inv_s; + + const float val0 = __shfl_sync(0xFFFFFFFF, scaled_val, base, WARP_SIZE); + const float val1 = __shfl_sync(0xFFFFFFFF, scaled_val, base + 16, WARP_SIZE); + const float val2 = __shfl_sync(0xFFFFFFFF, scaled_val, base + 1, WARP_SIZE); + const float val3 = __shfl_sync(0xFFFFFFFF, scaled_val, base + 17, WARP_SIZE); + + if (lane_in_group == 0) { + __nv_fp4x4_e2m1 fp4_packed(make_float4(val0, val1, val2, val3)); + + yqs2[quad_idx_in_block * 16 + b * 8 + group_id] = *(char2 *) &fp4_packed; + } +#else + // Fallback: manual FP4 conversion using LUT + const uint8_t q_val = ggml_cuda_float_to_fp4_e2m1(xi, inv_s); + + const uint8_t q_lo_0 = __shfl_sync(0xFFFFFFFF, q_val, base, WARP_SIZE); + const uint8_t q_lo_1 = __shfl_sync(0xFFFFFFFF, q_val, base + 1, WARP_SIZE); + const uint8_t q_hi_0 = __shfl_sync(0xFFFFFFFF, q_val, base + 16, WARP_SIZE); + const uint8_t q_hi_1 = __shfl_sync(0xFFFFFFFF, q_val, base + 17, WARP_SIZE); + + if (lane_in_group == 0) { + char2 q; + q.x = (q_hi_0 << 4) | q_lo_0; + q.y = (q_hi_1 << 4) | q_lo_1; + yqs2[quad_idx_in_block * 16 + b * 8 + group_id] = q; + } +#endif // CUDART_VERSION >= 12080 + } + + if (lane_id_32 == 0) { + // Store 2 scales packed into 1 uint32 + y[ib].d4[quad_idx_in_block] = (scales[1] << 8) | scales[0]; + } +} + +template <mmq_q8_1_ds_layout ds_layout> +static __global__ void quantize_mmq_q8_1( + const float * __restrict__ x, const int32_t * __restrict__ ids, void * __restrict__ vy, + const int64_t ne00, const int64_t s01, const int64_t s02, const int64_t s03, + const int64_t ne0, const int ne1, const int ne2) { + + constexpr int vals_per_scale = ds_layout == MMQ_Q8_1_DS_LAYOUT_D2S6 ? 64 : 32; + constexpr int vals_per_sum = ds_layout == MMQ_Q8_1_DS_LAYOUT_D2S6 ? 16 : 32; + + const int64_t i0 = ((int64_t)blockDim.x*blockIdx.y + threadIdx.x)*4; + + if (i0 >= ne0) { + return; + } + + const int64_t i1 = blockIdx.x; + const int64_t i2 = blockIdx.z % ne2; + const int64_t i3 = blockIdx.z / ne2; + + const int64_t i00 = i0; + const int64_t i01 = ids ? ids[i1] : i1; + const int64_t i02 = i2; + const int64_t i03 = i3; + + const float4 * x4 = (const float4 *) x; + + block_q8_1_mmq * y = (block_q8_1_mmq *) vy; + + const int64_t ib0 = blockIdx.z*((int64_t)gridDim.x*gridDim.y*blockDim.x/QK8_1); // first block of channel + const int64_t ib = ib0 + (i0 / (4*QK8_1))*ne1 + blockIdx.x; // block index in channel + const int64_t iqs = i0 % (4*QK8_1); // quant index in block + + // Load 4 floats per thread and calculate max. abs. value between them: + const float4 xi = i0 < ne00 ? x4[(i03*s03 + i02*s02 + i01*s01 + i00)/4] : make_float4(0.0f, 0.0f, 0.0f, 0.0f); + float amax = fabsf(xi.x); + amax = fmaxf(amax, fabsf(xi.y)); + amax = fmaxf(amax, fabsf(xi.z)); + amax = fmaxf(amax, fabsf(xi.w)); + + // Exchange max. abs. value between vals_per_scale/4 threads. +#pragma unroll + for (int offset = vals_per_scale/8; offset > 0; offset >>= 1) { + amax = fmaxf(amax, __shfl_xor_sync(0xFFFFFFFF, amax, offset, WARP_SIZE)); + } + + float sum; + if (ds_layout != MMQ_Q8_1_DS_LAYOUT_D4) { + sum = xi.x + xi.y + xi.z + xi.w; + + // Calculate sums across vals_per_sum/4 threads. +#pragma unroll + for (int offset = vals_per_sum/8; offset > 0; offset >>= 1) { + sum += __shfl_xor_sync(0xFFFFFFFF, sum, offset, WARP_SIZE); + } + } + + const float d_inv = 127.0f / amax; + char4 q; + q.x = roundf(xi.x*d_inv); + q.y = roundf(xi.y*d_inv); + q.z = roundf(xi.z*d_inv); + q.w = roundf(xi.w*d_inv); + + // Write back 4 int8 values as a single 32 bit value for better memroy bandwidth: + char4 * yqs4 = (char4 *) y[ib].qs; + yqs4[iqs/4] = q; + + if (ds_layout == MMQ_Q8_1_DS_LAYOUT_D2S6) { + if (iqs % 16 != 0 || iqs >= 96) { + return; + } + + y[ib].d2s6[2 + iqs/16] = sum; + + if (iqs % 64 != 0) { + return; + } + + const float d = 1.0f / d_inv; + + y[ib].d2s6[iqs/64] = d; + + return; + } + + if (iqs % 32 != 0) { + return; + } + + const float d = 1.0f / d_inv; + + if (ds_layout == MMQ_Q8_1_DS_LAYOUT_DS4) { + y[ib].ds4[iqs/32] = make_half2(d, sum); + } else { + y[ib].d4[iqs/32] = d; + } +} + +void quantize_row_q8_1_cuda( + const float * x, const int32_t * ids, void * vy, const ggml_type type_src0, + const int64_t ne00, const int64_t s01, const int64_t s02, const int64_t s03, + const int64_t ne0, const int64_t ne1, const int64_t ne2, const int64_t ne3, cudaStream_t stream) { + GGML_ASSERT(!ids); + GGML_ASSERT(ne0 % QK8_1 == 0); + + const uint3 ne2_fastdiv = init_fastdiv_values(ne2); + + const int64_t block_num_x = (ne0 + CUDA_QUANTIZE_BLOCK_SIZE - 1) / CUDA_QUANTIZE_BLOCK_SIZE; + const dim3 num_blocks(block_num_x, ne1, ne2*ne3); + const dim3 block_size(CUDA_QUANTIZE_BLOCK_SIZE, 1, 1); + quantize_q8_1<<<num_blocks, block_size, 0, stream>>>(x, vy, ne00, s01, s02, s03, ne0, ne1, ne2_fastdiv); + GGML_UNUSED(type_src0); +} + +void quantize_mmq_q8_1_cuda( + const float * x, const int32_t * ids, void * vy, const ggml_type type_src0, + const int64_t ne00, const int64_t s01, const int64_t s02, const int64_t s03, + const int64_t ne0, const int64_t ne1, const int64_t ne2, const int64_t ne3, cudaStream_t stream) { + GGML_ASSERT(ne00 % 4 == 0); + GGML_ASSERT(ne0 % (4*QK8_1) == 0); + + // ne1 tends to assume the highest values, therefore use it as the "x" dimension of the CUDA grid: + const int64_t block_num_y = (ne0 + 4*CUDA_QUANTIZE_BLOCK_SIZE_MMQ - 1) / (4*CUDA_QUANTIZE_BLOCK_SIZE_MMQ); + const dim3 num_blocks(ne1, block_num_y, ne2*ne3); + const dim3 block_size(CUDA_QUANTIZE_BLOCK_SIZE_MMQ, 1, 1); + switch (mmq_get_q8_1_ds_layout(type_src0)) { + case MMQ_Q8_1_DS_LAYOUT_D4: + quantize_mmq_q8_1<MMQ_Q8_1_DS_LAYOUT_D4> + <<<num_blocks, block_size, 0, stream>>>(x, ids, vy, ne00, s01, s02, s03, ne0, ne1, ne2); + break; + case MMQ_Q8_1_DS_LAYOUT_DS4: + quantize_mmq_q8_1<MMQ_Q8_1_DS_LAYOUT_DS4> + <<<num_blocks, block_size, 0, stream>>>(x, ids, vy, ne00, s01, s02, s03, ne0, ne1, ne2); + break; + case MMQ_Q8_1_DS_LAYOUT_D2S6: + quantize_mmq_q8_1<MMQ_Q8_1_DS_LAYOUT_D2S6> + <<<num_blocks, block_size, 0, stream>>>(x, ids, vy, ne00, s01, s02, s03, ne0, ne1, ne2); + break; + default: + GGML_ABORT("fatal error"); + break; + } +} + +void quantize_mmq_mxfp4_cuda(const float * x, + const int32_t * ids, + void * vy, + [[maybe_unused]] const ggml_type type_src0, + const int64_t ne00, + const int64_t s01, + const int64_t s02, + const int64_t s03, + const int64_t ne0, + const int64_t ne1, + const int64_t ne2, + const int64_t ne3, + cudaStream_t stream) { + GGML_ASSERT(ne0 % (2 * QK_MXFP4) == 0); + + constexpr int nwarps = 8; + constexpr int vals_per_warp = 2 * QK_MXFP4; + constexpr int vals_per_block = nwarps * vals_per_warp; + + const int64_t block_num_y = (ne0 + vals_per_block - 1) / vals_per_block; + const dim3 num_blocks(ne1, block_num_y, ne2 * ne3); + const dim3 block_size(WARP_SIZE, nwarps, 1); + + quantize_mmq_mxfp4<<<num_blocks, block_size, 0, stream>>>(x, ids, vy, ne00, s01, s02, s03, ne0, ne1, ne2); +} |
