Files
project_6/ex_engine/xllm_layers/mlu/qwen3_5_attention.cpp
project6-dev f28223c9da perf: native ixformer decode (v1 ≤32K, v2 >32K) + flash_attn_varlen prefill
Replaces all Python PyTorch fallback attention with native ixformer kernels:

Decode path:
- ≤32K: paged_attention_v1 (5D KV layout, x=8) — verified on real BI-V100
- >32K: paged_attention_v2 (5D→4D permute) — verified 65K+ on real BI-V100
- Removes _forward_decode_pytorch Python fallback entirely

Prefill path (profiling):
- _run_sdpa_fallback now uses ixformer.flash_attn_varlen_func
- head_dim=256 verified correct (diff<0.004) and 1.7x faster than PyTorch
- Falls back to Q-tiling pure-math if ixformer unavailable

Also includes: MoE kernel integration, GDN C++ kernels, diagnostic scripts,
xllm upstream layer/kernel references, .dockerignore cleanup.

All changes verified on real BI-V100 hardware (single card).
2026-08-13 07:04:21 +00:00

237 lines
8.6 KiB
C++

/* Copyright 2026 The xLLM Authors. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
https://github.com/jd-opensource/xllm/blob/main/LICENSE
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/
#include "qwen3_5_attention.h"
#include <glog/logging.h>
#include <tuple>
#include "kernels/ops_api.h"
namespace xllm {
namespace layer {
Qwen3_5AttentionImpl::Qwen3_5AttentionImpl(const ModelArgs& args,
const QuantArgs& quant_args,
const ParallelArgs& parallel_args,
const torch::TensorOptions& options,
int32_t layer_id) {
const int64_t tp_size = parallel_args.tp_group_->world_size();
const int64_t total_num_heads = args.n_heads();
const int64_t total_num_kv_heads = args.n_kv_heads().value_or(args.n_heads());
layer_id_ = layer_id;
rank_ = parallel_args.tp_group_->rank();
CHECK(total_num_heads % tp_size == 0);
num_heads_ = total_num_heads / tp_size;
if (total_num_kv_heads >= tp_size) {
CHECK(total_num_kv_heads % tp_size == 0);
num_kv_heads_ = total_num_kv_heads / tp_size;
num_kv_head_replicas_ = 1;
} else {
CHECK(tp_size % total_num_kv_heads == 0);
num_kv_heads_ = 1;
num_kv_head_replicas_ = tp_size / total_num_kv_heads;
}
head_dim_ = args.head_dim();
q_size_ = num_heads_ * head_dim_;
kv_size_ = num_kv_heads_ * head_dim_;
scaling_ = 1.0f / std::sqrt(static_cast<float>(head_dim_));
attn_output_gate_ = args.attn_output_gate();
mrope_cu_seq_lens_ = torch::zeros(2, torch::kInt32).to(options.device());
// 1. QKV linear
qkv_proj_ = register_module(
"qkv_proj",
QKVParallelLinear(args.hidden_size(),
attn_output_gate_ ? num_heads_ * 2 : num_heads_,
num_kv_heads_,
args.head_dim(),
num_kv_head_replicas_,
/*bias=*/args.attention_bias(),
/*gather_output=*/false,
parallel_args,
options));
// 2. O proj
o_proj_ = register_module("o_proj",
RowParallelLinear(total_num_heads * head_dim_,
args.hidden_size(),
/*bias=*/false,
/*input_is_parallelized=*/true,
/*if_reduce_results=*/true,
quant_args,
parallel_args.tp_group_,
options));
// 3. Q norm
q_norm_ = register_module(
"q_norm", Qwen3NextRMSNorm(head_dim_, args.rms_norm_eps(), options));
// 4. K norm
k_norm_ = register_module(
"k_norm", Qwen3NextRMSNorm(head_dim_, args.rms_norm_eps(), options));
// 5. Attention
attn_ = register_module("attn",
Attention(num_heads_,
head_dim_,
scaling_,
num_kv_heads_,
args.sliding_window()));
// 6. Rotary embedding
const int32_t rotary_dim =
static_cast<int32_t>(head_dim_ * args.partial_rotary_factor());
rotary_emb_ =
register_module("rope",
MRotaryEmbedding(rotary_dim,
args.max_position_embeddings(),
args.rope_theta(),
/*interleaved=*/false,
args.rope_scaling_mrope_section(),
options));
}
void Qwen3_5AttentionImpl::rotary_emb_forward(
torch::Tensor& q,
torch::Tensor& k,
const torch::Tensor& positions,
const AttentionMetadata& attn_metadata) {
auto q_shape = q.sizes();
auto k_shape = k.sizes();
auto num_tokens = positions.size(-1);
mrope_cu_seq_lens_[1] = num_tokens;
xllm::kernel::RotaryParams rotary_params;
bool only_prefill =
(attn_metadata.is_prefill || attn_metadata.is_chunked_prefill);
if (only_prefill) {
rotary_params.sin = attn_metadata.mrope_sin;
rotary_params.cos = attn_metadata.mrope_cos;
rotary_params.position_ids = std::nullopt;
rotary_params.cu_query_lens = mrope_cu_seq_lens_;
rotary_params.interleaved = false;
rotary_params.discrete = false;
rotary_params.max_query_len = num_tokens;
rotary_params.q = q.view({num_tokens, -1, head_dim_});
xllm::kernel::apply_rotary(rotary_params);
q = rotary_params.q.reshape(q_shape);
rotary_params.q = k.view({num_tokens, -1, head_dim_});
xllm::kernel::apply_rotary(rotary_params);
k = rotary_params.q.reshape(k_shape);
} else {
if (positions.dim() == 2) {
rotary_params.position_ids = positions[0];
} else {
rotary_params.position_ids = positions;
}
rotary_params.sin = rotary_emb_->get_sin_cache();
rotary_params.cos = rotary_emb_->get_cos_cache();
rotary_params.interleaved = false;
rotary_params.discrete = true;
rotary_params.max_query_len = num_tokens;
rotary_params.q = q.view({1, num_tokens, -1, head_dim_});
xllm::kernel::apply_rotary(rotary_params);
q = rotary_params.q.reshape(q_shape);
rotary_params.q = k.view({1, num_tokens, -1, head_dim_});
xllm::kernel::apply_rotary(rotary_params);
k = rotary_params.q.reshape(k_shape);
}
}
torch::Tensor Qwen3_5AttentionImpl::forward(
const torch::Tensor& positions,
const torch::Tensor& hidden_states,
const AttentionMetadata& attn_metadata,
KVCache& kv_cache) {
// 1. qkv projection
auto qkv = qkv_proj_->forward(hidden_states);
torch::Tensor q, k, v;
torch::Tensor gate;
if (attn_output_gate_) {
// Split qkv for attn_output_gate case: [q_size*2, kv_size, kv_size]
auto q_gate = qkv.slice(/*dim=*/-1, 0, q_size_ * 2);
k = qkv.slice(/*dim=*/-1, q_size_ * 2, q_size_ * 2 + kv_size_);
v = qkv.slice(
/*dim=*/-1, q_size_ * 2 + kv_size_, q_size_ * 2 + kv_size_ * 2);
v = v.contiguous();
std::vector<int64_t> orig_shape;
for (int64_t i = 0; i < q_gate.dim() - 1; i++) {
orig_shape.push_back(q_gate.size(i));
}
std::vector<int64_t> new_shape = orig_shape;
new_shape.push_back(num_heads_);
new_shape.push_back(-1);
torch::Tensor q_gate_reshaped = q_gate.reshape(new_shape);
auto chunks = torch::chunk(q_gate_reshaped, 2, /*dim=*/-1);
q = chunks[0];
gate = chunks[1];
std::vector<int64_t> q_new_shape = orig_shape;
q_new_shape.push_back(-1);
q = q.reshape(q_new_shape);
std::vector<int64_t> gate_new_shape = orig_shape;
gate_new_shape.push_back(-1);
gate = gate.reshape(gate_new_shape);
} else {
// Normal case: [q_size, kv_size, kv_size]
q = qkv.slice(/*dim=*/-1, 0, q_size_);
k = qkv.slice(/*dim=*/-1, q_size_, q_size_ + kv_size_);
v = qkv.slice(/*dim=*/-1, q_size_ + kv_size_, q_size_ + 2 * kv_size_);
}
const int64_t T = q.size(0);
auto q_reshaped = q.reshape({T, num_heads_, head_dim_});
auto q_normed = std::get<0>(q_norm_->forward(q_reshaped));
auto k_reshaped = k.reshape({T, num_kv_heads_, head_dim_});
auto k_normed = std::get<0>(k_norm_->forward(k_reshaped));
q = q_normed.view({T, q_size_});
k = k_normed.view({T, kv_size_});
rotary_emb_forward(q, k, positions, attn_metadata);
auto out = std::get<0>(attn_->forward(attn_metadata, q, k, v, kv_cache));
if (attn_output_gate_) {
gate = torch::sigmoid(gate);
out = out * gate;
}
out = o_proj_->forward(out);
return out;
}
void Qwen3_5AttentionImpl::load_state_dict(const StateDict& state_dict) {
qkv_proj_->load_state_dict(state_dict, {"q_proj.", "k_proj.", "v_proj."});
o_proj_->load_state_dict(state_dict.get_dict_with_prefix("o_proj."));
if (auto w = state_dict.get_tensor("q_norm.weight"); w.defined()) {
q_norm_->load_state_dict(StateDict({{"weight", w}}));
}
if (auto w = state_dict.get_tensor("k_norm.weight"); w.defined()) {
k_norm_->load_state_dict(StateDict({{"weight", w}}));
}
}
} // namespace layer
} // namespace xllm