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llama.cpp/ggml/src/ggml-cuda/mmf.cu
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Pranesh Gonegandlaandpraneshgo 5839ba3524 CUDA: dedup MoE gate/up activation quantization (#25441)
* CUDA: dedup MoE gate/up activation quantization (fp4)

For MoE gate/up projections the src1 activation is broadcast across the
routed experts (ne11 == 1), so ids_src1 maps every one of a token's
n_expert_used slots to the same physical row. The MMQ path therefore
re-quantized each token's activation n_expert_used times.

For fp4 (NVFP4/MXFP4) src0, quantize each unique token row once instead of
once per expert. For NVFP4 a single quantize+scatter kernel
(quantize_scatter_mmq_nvfp4) quantizes each token once and writes the
resulting block_fp4_mmq straight to all n_expert_used slots, using an
inverse token->compact-row map (build_tok2c). MXFP4, and
GGML_CUDA_MOE_QUANT_GATHER=1, use a two-kernel variant: quantize unique
rows then gather into the expert-sorted layout (gather_mmq_fp4_blocks).
Both are bit-identical to the previous gather-then-quantize path (identical
source data, deterministic per-block quantization), verified by
test-backend-ops MUL_MAT_ID (type_a=nvfp4, broadcast b=1; 790/790 for the
default, gather, and per-expert paths) and by coherent end-to-end
generation. Set GGML_CUDA_NO_MOE_QUANT_DEDUP=1 to force the original
per-expert path.

Same-binary A/B on RTX 5090 (sm_120), Qwen3.6-35B-A3B-NVFP4 prefill @8192
(nsys, graphs-off; the unchanged mul_mat_q GEMM confirms stable clocks):
activation-quant GPU-busy drops 61% (78.2 -> 30.4 ms) with the fused
quantize+scatter, vs 33% (78.2 -> 52.8 ms) for the two-kernel gather. The
fused path avoids materializing and re-reading the 8x compact buffer,
writing the expert copies directly from registers.

* CUDA: bounds-check token ids in build_tok2c_kernel

Guard against malformed ids_src1: skip out-of-range token ids (t < 0 or
t >= n_tokens) and drop entries beyond n_expert_used per token instead of
writing past the token's tok2c region. No behavior change for valid MoE
routing data; test-backend-ops MUL_MAT_ID 790/790.

* Refactor the code based on review comments

- Removed previously added kernels that were not necessary anymore\
- Added an inverse mapping from (token, slot) to compact row. Each token is quantized once and scattered to its compact rows.

* Adding q8_1 support for dedup and addressing review comments

* Add pragma unrolls

* Remove redundant cudaMemsetAsync call

* Removing follow up redundancies

---------

Co-authored-by: praneshgo <227579474+praneshgo@users.noreply.github.com>
2026-07-16 09:02:25 +02:00

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#include "ggml.h"
#include "mmf.cuh"
#include "mmid.cuh"
static __forceinline__ int mmf_get_rows_per_block(const int cc) {
if (GGML_CUDA_CC_IS_CDNA(cc)) {
return MMF_ROWS_PER_BLOCK_CDNA;
} else {
return MMF_ROWS_PER_BLOCK;
}
}
void ggml_cuda_mul_mat_f(ggml_backend_cuda_context & ctx, const ggml_tensor * src0, const ggml_tensor * src1, const ggml_tensor * ids, ggml_tensor * dst) {
GGML_ASSERT( src1->type == GGML_TYPE_F32);
GGML_ASSERT(!ids || ids->type == GGML_TYPE_I32);
GGML_ASSERT( dst->type == GGML_TYPE_F32);
GGML_TENSOR_BINARY_OP_LOCALS;
const size_t ts_src0 = ggml_type_size(src0->type);
const size_t ts_src1 = ggml_type_size(src1->type);
const size_t ts_dst = ggml_type_size(dst->type);
GGML_ASSERT(ne13 == ne3);
GGML_ASSERT( nb00 == ts_src0);
GGML_ASSERT( nb10 == ts_src1);
GGML_ASSERT(!ids || ids->nb[0] == ggml_type_size(ids->type));
GGML_ASSERT( nb0 == ts_dst);
const float * src1_d = (const float *) src1->data;
const int32_t * ids_d = ids ? (const int32_t *) ids->data : nullptr;
float * dst_d = (float *) dst->data;
const int64_t s01 = src0->nb[1] / ts_src0;
const int64_t s11 = src1->nb[1] / ts_src1;
const int64_t s1 = dst->nb[1] / ts_dst;
const int64_t s02 = src0->nb[2] / ts_src0;
const int64_t s12 = src1->nb[2] / ts_src1;
const int64_t s2 = dst->nb[2] / ts_dst;
const int64_t s03 = src0->nb[3] / ts_src0;
const int64_t s13 = src1->nb[3] / ts_src1;
const int64_t s3 = dst->nb[3] / ts_dst;
const int64_t ids_s0 = ids ? ids->nb[0] / ggml_type_size(ids->type) : 0;
const int64_t ids_s1 = ids ? ids->nb[1] / ggml_type_size(ids->type) : 0;
mmf_ids_data ids_info{};
mmf_ids_data * ids_info_ptr = nullptr;
ggml_cuda_pool_alloc<int32_t> ids_src_compact_dev;
ggml_cuda_pool_alloc<int32_t> ids_dst_compact_dev;
ggml_cuda_pool_alloc<int32_t> expert_bounds_dev;
// For MUL_MAT_ID the memory layout is different than for MUL_MAT:
const int64_t ncols_dst = ids ? ne2 : ne1;
const int64_t nchannels_dst = ids ? ne1 : ne2;
const int64_t stride_col_dst = ids ? s2 : s1;
const int64_t stride_col_y = ids ? s12 : s11;
const int64_t stride_channel_dst = ids ? s1 : s2;
int64_t stride_channel_y = ids ? s11 : s12;
int64_t nchannels_y = ids ? ne11 : ne12;
//mul_mat_id: handle broadcast
if (ids && nchannels_y == 1) {
stride_channel_y = 0;
nchannels_y = ids->ne[0];
}
if (ids && ncols_dst > 16) {
const int64_t n_expert_used = ids->ne[0];
const int64_t n_experts = ne02;
const int64_t n_tokens = ne12;
const int64_t ne_get_rows = n_tokens * n_expert_used;
ids_src_compact_dev.alloc(ctx.pool(), ne_get_rows);
ids_dst_compact_dev.alloc(ctx.pool(), ne_get_rows);
expert_bounds_dev.alloc(ctx.pool(), n_experts + 1);
const int si1 = static_cast<int>(ids_s1);
const int sis1 = static_cast<int>(src1->nb[2] / src1->nb[1]);
GGML_ASSERT(sis1 > 0);
ggml_cuda_launch_mm_ids_helper(ids_d, ids_src_compact_dev.get(), ids_dst_compact_dev.get(), expert_bounds_dev.get(),
static_cast<int>(n_experts), static_cast<int>(n_tokens), static_cast<int>(n_expert_used), static_cast<int>(ne11), si1, sis1, /*write_inverse =*/ false, ctx.stream());
CUDA_CHECK(cudaGetLastError());
ids_info.ids_src_compact = ids_src_compact_dev.get();
ids_info.ids_dst_compact = ids_dst_compact_dev.get();
ids_info.expert_bounds_dev = expert_bounds_dev.get();
ids_info.n_experts = static_cast<int>(n_experts);
ids_info.sis1 = sis1;
ids_info_ptr = &ids_info;
}
const int device = ggml_cuda_get_device();
const int cc = ggml_cuda_info().devices[device].cc;
const int rows_per_block = mmf_get_rows_per_block(cc);
switch (src0->type) {
case GGML_TYPE_F32: {
const float * src0_d = (const float *) src0->data;
constexpr int vals_per_T = 1;
mul_mat_f_switch_rows_per_block<float>(
rows_per_block, src0_d, src1_d, ids_d, dst_d, ne00/vals_per_T, ne01, ncols_dst, s01/vals_per_T, stride_col_y/vals_per_T, stride_col_dst,
ids_s0, ids_s1, ne02, nchannels_y, nchannels_dst, s02/vals_per_T, stride_channel_y, stride_channel_dst,
ne03, ne3, s03/vals_per_T, s13, s3, ctx.stream(), ids_info_ptr);
} break;
case GGML_TYPE_F16: {
const half2 * src0_d = (const half2 *) src0->data;
constexpr int vals_per_T = 2;
mul_mat_f_switch_rows_per_block<half2>(
rows_per_block, src0_d, src1_d, ids_d, dst_d, ne00/vals_per_T, ne01, ncols_dst, s01/vals_per_T, stride_col_y/vals_per_T, stride_col_dst,
ids_s0, ids_s1, ne02, nchannels_y, nchannels_dst, s02/vals_per_T, stride_channel_y, stride_channel_dst,
ne03, ne3, s03/vals_per_T, s13, s3, ctx.stream(), ids_info_ptr);
} break;
case GGML_TYPE_BF16: {
const nv_bfloat162 * src0_d = (const nv_bfloat162 *) src0->data;
constexpr int vals_per_T = 2;
mul_mat_f_switch_rows_per_block<nv_bfloat162>(
rows_per_block, src0_d, src1_d, ids_d, dst_d, ne00/vals_per_T, ne01, ncols_dst, s01/vals_per_T, stride_col_y/vals_per_T, stride_col_dst,
ids_s0, ids_s1, ne02, nchannels_y, nchannels_dst, s02/vals_per_T, stride_channel_y, stride_channel_dst,
ne03, ne3, s03/vals_per_T, s13, s3, ctx.stream(), ids_info_ptr);
} break;
default:
GGML_ABORT("unsupported type: %s", ggml_type_name(src0->type));
}
}
bool ggml_cuda_should_use_mmf(enum ggml_type type, int cc, int warp_size, const int64_t * src0_ne,
const size_t * src0_nb, const int src1_ncols, bool mul_mat_id) {
if (ggml_is_quantized(type)) {
return false;
}
const size_t ts = ggml_type_size(type);
if (src0_ne[0] % (warp_size * (4/ts)) != 0) {
return false;
}
if (src0_nb[0] != ts) {
return false;
}
// Pointers not aligned to the size of half2/nv_bfloat162/float2 would result in a crash:
for (size_t i = 1; i < GGML_MAX_DIMS; ++i) {
if (src0_nb[i] % (2*ts) != 0) {
return false;
}
}
if (src0_ne[1] % mmf_get_rows_per_block(cc) != 0) {
return false;
}
if (GGML_CUDA_CC_IS_CDNA3(cc) && type == GGML_TYPE_BF16) {
return false;
}
if (mul_mat_id) {
if (src0_ne[1] <= 1024 && src1_ncols > 512) {
return false;
} else if(src0_ne[1] > 1024 && src1_ncols > 128) {
return false;
}
} else {
if (GGML_CUDA_CC_IS_RDNA3_0(cc) && src1_ncols > 8) {
return false;
} else if (GGML_CUDA_CC_IS_CDNA2(cc) && (type == GGML_TYPE_F16 || type == GGML_TYPE_BF16)) {
//TODO: truse CDNA2 as CDNA1, tune the perf when CDNA2 is available.
return false;
} else if (GGML_CUDA_CC_IS_CDNA1(cc) && (type == GGML_TYPE_F16 || type == GGML_TYPE_BF16)) {
return false;
} else if (src1_ncols > 16) {
return false;
}
}
switch (type) {
case GGML_TYPE_F32:
return ampere_mma_available(cc) || amd_mfma_available(cc);
case GGML_TYPE_F16:
return volta_mma_available(cc) || turing_mma_available(cc) || amd_wmma_available(cc) || amd_mfma_available(cc);
case GGML_TYPE_BF16:
return ampere_mma_available(cc) || amd_wmma_available(cc) || amd_mfma_available(cc);
default:
return false;
}
}