Support DeepSeek V3.2 Exp (#11061)

Co-authored-by: Stefan He <11166516+hebiao064@users.noreply.github.com>
Co-authored-by: Liangsheng Yin <95566987+hnyls2002@users.noreply.github.com>
Co-authored-by: Baizhou Zhang <56809903+fridge003@users.noreply.github.com>
Co-authored-by: DarkSharpness <76582120+darksharpness@users.noreply.github.com>
Co-authored-by: ZhengdQin <46387172+zhengdqin@users.noreply.github.com>
Co-authored-by: DarkSharpness <2040703891@qq.com>
Co-authored-by: hnyls2002 <lsyincs@gmail.com>
Co-authored-by: Zhengda Qin <zhengdqin@gmail.com>
Co-authored-by: Liangsheng Yin <hnyls2002@gmail.com>
Co-authored-by: HAI <hixiao@gmail.com>
Co-authored-by: Baizhou Zhang <sobereddiezhang@gmail.com>
This commit is contained in:
fzyzcjy
2025-10-06 00:24:15 -07:00
committed by GitHub
co-authored by Stefan He Liangsheng Yin Baizhou Zhang DarkSharpness ZhengdQin DarkSharpness hnyls2002 Zhengda Qin Liangsheng Yin HAI Baizhou Zhang
parent 292a867ad9
commit efbc687c28
29 changed files with 4540 additions and 139 deletions
@@ -0,0 +1,887 @@
from __future__ import annotations
import sys
from dataclasses import dataclass
from typing import TYPE_CHECKING, Dict, List, Literal, Optional, TypeAlias
import torch
from sglang.srt.configs.model_config import get_nsa_index_topk, is_deepseek_nsa
from sglang.srt.layers.attention.base_attn_backend import AttentionBackend
from sglang.srt.layers.attention.nsa.nsa_indexer import BaseIndexerMetadata
from sglang.srt.layers.attention.nsa.quant_k_cache import quantize_k_cache
from sglang.srt.layers.attention.nsa.transform_index import (
transform_index_page_table_decode,
transform_index_page_table_prefill,
)
from sglang.srt.layers.attention.nsa.utils import (
NSA_FLASHMLA_BACKEND_DECODE_COMPUTE_FP8,
NSA_FUSE_TOPK,
compute_nsa_seqlens,
)
from sglang.srt.layers.dp_attention import get_attention_tp_size
from sglang.srt.model_executor.forward_batch_info import ForwardBatch, ForwardMode
from sglang.srt.utils import is_hip
# from sgl_kernel.flash_attn import flash_attn_varlen_func, flash_attn_with_kvcache
if TYPE_CHECKING:
from sglang.srt.layers.radix_attention import RadixAttention
from sglang.srt.model_executor.model_runner import ModelRunner
from sglang.srt.speculative.spec_info import SpecInput
_is_hip = is_hip()
if _is_hip:
try:
from aiter import (
flash_attn_varlen_func,
mha_batch_prefill_func,
paged_attention_ragged,
)
from aiter.mla import mla_decode_fwd, mla_prefill_fwd
except ImportError:
print(
"aiter is AMD specific kernel library. Please make sure aiter is installed on your AMD device."
)
else:
from sgl_kernel.flash_attn import flash_attn_varlen_func, flash_attn_with_kvcache
@dataclass(frozen=True)
class NSAFlashMLAMetadata:
"""Metadata only needed by FlashMLA"""
flashmla_metadata: torch.Tensor
num_splits: torch.Tensor
def slice(self, sli):
return NSAFlashMLAMetadata(
flashmla_metadata=self.flashmla_metadata,
num_splits=self.num_splits[sli],
)
def copy_(self, other: "NSAFlashMLAMetadata"):
self.flashmla_metadata.copy_(other.flashmla_metadata)
self.num_splits.copy_(other.num_splits)
@dataclass(frozen=True)
class NSAMetadata:
page_size: int
# Sequence lengths for the forward batch
cache_seqlens_int32: torch.Tensor
# Maximum sequence length for query
max_seq_len_q: int
# Maximum sequence length for key
max_seq_len_k: int
# Cumulative sequence lengths for query
cu_seqlens_q: torch.Tensor
# Cumulative sequence lengths for key
cu_seqlens_k: torch.Tensor
# Page table, the index of KV Cache Tables/Blocks
# this table is always with page_size = 1
page_table_1: torch.Tensor
# NOTE(dark): This will property be used in:
# 1. dense decode/prefill, we use paged flash attention, need real_page_table
# 2. sparse decode/prefill, indexer need real_page_table to compute the score
real_page_table: torch.Tensor
# NSA metadata (nsa prefill are expanded)
nsa_cache_seqlens_int32: torch.Tensor # this seqlens is clipped to `topk`
nsa_cu_seqlens_q: torch.Tensor # must be arange(0, len(nsa_cu_seqlens_k))
nsa_cu_seqlens_k: torch.Tensor # cumsum of `nsa_cache_seqlens_int32`
nsa_extend_seq_lens_list: List[int]
nsa_seqlens_expanded: torch.Tensor # expanded, unclipped `seqlens`
nsa_max_seqlen_q: Literal[1] = 1 # always 1 for decode, variable for extend
flashmla_metadata: Optional[NSAFlashMLAMetadata] = None
@dataclass(frozen=True)
class NSAIndexerMetadata(BaseIndexerMetadata):
attn_metadata: NSAMetadata
def get_seqlens_int32(self) -> torch.Tensor:
return self.attn_metadata.cache_seqlens_int32
def get_page_table_64(self) -> torch.Tensor:
return self.attn_metadata.real_page_table
def get_seqlens_expanded(self) -> torch.Tensor:
return self.attn_metadata.nsa_seqlens_expanded
def topk_transform(
self,
logits: torch.Tensor,
topk: int,
) -> torch.Tensor:
from sgl_kernel import fast_topk_transform_fused, fast_topk_v2
if not NSA_FUSE_TOPK:
return fast_topk_v2(logits, self.get_seqlens_expanded(), topk)
# NOTE(dark): if fused, we return a transformed page table directly
return fast_topk_transform_fused(
score=logits,
lengths=self.get_seqlens_expanded(),
page_table_size_1=self.attn_metadata.page_table_1,
cu_seqlens_q=self.attn_metadata.cu_seqlens_q,
topk=topk,
)
def compute_cu_seqlens(seqlens: torch.Tensor) -> torch.Tensor:
assert seqlens.dtype == torch.int32 and seqlens.is_cuda
return torch.nn.functional.pad(
torch.cumsum(seqlens, dim=0, dtype=torch.int32), (1, 0)
)
_NSA_IMPL_T: TypeAlias = Literal[
"flashmla_prefill", "flashmla_decode", "fa3", "tilelang"
]
NSA_PREFILL_IMPL: _NSA_IMPL_T
NSA_DECODE_IMPL: _NSA_IMPL_T
class NativeSparseAttnBackend(AttentionBackend):
def __init__(self, model_runner: ModelRunner):
super().__init__()
self.forward_metadata: NSAMetadata
self.device = model_runner.device
assert isinstance(model_runner.page_size, int)
self.real_page_size = model_runner.page_size
self.num_splits = (
1 if model_runner.server_args.enable_deterministic_inference else 0
)
self.use_nsa = is_deepseek_nsa(model_runner.model_config.hf_config)
assert self.use_nsa, "NSA backend only supports DeepSeek NSA"
self.nsa_kv_cache_store_fp8 = (
model_runner.token_to_kv_pool.nsa_kv_cache_store_fp8
)
self.nsa_index_topk = get_nsa_index_topk(model_runner.model_config.hf_config)
self.max_context_len = model_runner.model_config.context_len
self.num_q_heads = (
model_runner.model_config.num_attention_heads // get_attention_tp_size()
)
self.kv_cache_dim = model_runner.token_to_kv_pool.kv_cache_dim
assert model_runner.req_to_token_pool is not None
self.req_to_token = model_runner.req_to_token_pool.req_to_token
global NSA_PREFILL_IMPL, NSA_DECODE_IMPL
NSA_PREFILL_IMPL = model_runner.server_args.nsa_prefill
NSA_DECODE_IMPL = model_runner.server_args.nsa_decode
self._arange_buf = torch.arange(16384, device=self.device, dtype=torch.int32)
if _is_hip:
max_bs = model_runner.req_to_token_pool.size
self.kv_indptr = torch.zeros(
(max_bs + 1,), dtype=torch.int32, device=model_runner.device
)
def get_device_int32_arange(self, l: int) -> torch.Tensor:
if l > len(self._arange_buf):
next_pow_of_2 = 1 << (l - 1).bit_length()
self._arange_buf = torch.arange(
next_pow_of_2, device=self.device, dtype=torch.int32
)
return self._arange_buf[:l]
def _transform_table_1_to_real(self, page_table: torch.Tensor) -> torch.Tensor:
page_size = self.real_page_size
if page_size == 1:
return page_table
max_seqlen_k = page_table.shape[1]
strided_indices = torch.arange(
0, max_seqlen_k, page_size, device=page_table.device, dtype=torch.int32
)
return page_table[:, strided_indices] // page_size
def init_forward_metadata(self, forward_batch: ForwardBatch):
"""Init the metadata for a forward pass."""
batch_size = forward_batch.batch_size
device = forward_batch.seq_lens.device
assert (
forward_batch.spec_info is None
), "Spec decoding is not supported for NSA backend now"
cache_seqlens_int32 = forward_batch.seq_lens.to(torch.int32)
cu_seqlens_k = compute_cu_seqlens(cache_seqlens_int32)
assert forward_batch.seq_lens_cpu is not None
max_seqlen_k = int(forward_batch.seq_lens_cpu.max().item())
page_table = forward_batch.req_to_token_pool.req_to_token[
forward_batch.req_pool_indices, :max_seqlen_k
]
if forward_batch.forward_mode.is_decode_or_idle():
extend_seq_lens_cpu = [1] * batch_size
max_seqlen_q = 1
cu_seqlens_q = self.get_device_int32_arange(batch_size + 1)
seqlens_expanded = cache_seqlens_int32
elif forward_batch.forward_mode.is_extend():
assert (
forward_batch.extend_seq_lens_cpu is not None
and forward_batch.extend_seq_lens is not None
and forward_batch.extend_prefix_lens_cpu is not None
), "All of them must not be None"
extend_seq_lens_cpu = forward_batch.extend_seq_lens_cpu
assert forward_batch.extend_seq_lens is not None
if any(forward_batch.extend_prefix_lens_cpu):
max_seqlen_q = max(extend_seq_lens_cpu)
cu_seqlens_q = compute_cu_seqlens(
forward_batch.extend_seq_lens.to(torch.int32)
)
else:
max_seqlen_q = max_seqlen_k
cu_seqlens_q = cu_seqlens_k
seqlens_expanded = torch.cat(
[
torch.arange(
kv_len - qo_len + 1,
kv_len + 1,
dtype=torch.int32,
device=device,
)
for qo_len, kv_len in zip(
forward_batch.extend_seq_lens_cpu,
forward_batch.seq_lens_cpu.tolist(),
strict=True,
)
]
)
else:
assert False, f"Unsupported {forward_batch.forward_mode = }"
# 1D, expanded seqlens (1D means cheap to compute, so always compute it)
nsa_cache_seqlens_int32 = compute_nsa_seqlens(
original_seq_lens=seqlens_expanded,
nsa_index_topk=self.nsa_index_topk,
)
nsa_cu_seqlens_k = compute_cu_seqlens(nsa_cache_seqlens_int32)
nsa_cu_seqlens_q = self.get_device_int32_arange(len(nsa_cu_seqlens_k))
metadata = NSAMetadata(
page_size=self.real_page_size,
cache_seqlens_int32=cache_seqlens_int32,
max_seq_len_q=max_seqlen_q,
max_seq_len_k=max_seqlen_k,
cu_seqlens_q=cu_seqlens_q,
cu_seqlens_k=cu_seqlens_k,
page_table_1=page_table,
flashmla_metadata=(
self._compute_flashmla_metadata(
cache_seqlens=nsa_cache_seqlens_int32,
seq_len_q=1, # TODO handle MTP which is not 1
)
if NSA_DECODE_IMPL == "flashmla_decode"
else None
),
nsa_cache_seqlens_int32=nsa_cache_seqlens_int32,
nsa_cu_seqlens_q=nsa_cu_seqlens_q,
nsa_cu_seqlens_k=nsa_cu_seqlens_k,
nsa_seqlens_expanded=seqlens_expanded,
nsa_extend_seq_lens_list=extend_seq_lens_cpu,
real_page_table=self._transform_table_1_to_real(page_table),
)
self.forward_metadata = metadata
def init_cuda_graph_state(self, max_bs: int, max_num_tokens: int):
"""Initialize CUDA graph state for the attention backend.
Args:
max_bs (int): Maximum batch size to support in CUDA graphs
This creates fixed-size tensors that will be reused during CUDA graph replay
to avoid memory allocations.
"""
self.decode_cuda_graph_metadata: Dict = {
"cache_seqlens": torch.zeros(max_bs, dtype=torch.int32, device=self.device),
"cu_seqlens_q": torch.arange(
0, max_bs + 1, dtype=torch.int32, device=self.device
),
"cu_seqlens_k": torch.zeros(
max_bs + 1, dtype=torch.int32, device=self.device
),
# fake page_table for sparse_prefill
"page_table": torch.zeros(
max_bs,
self.max_context_len,
dtype=torch.int32,
device=self.device,
),
"flashmla_metadata": (
self._compute_flashmla_metadata(
cache_seqlens=torch.ones(
max_bs, dtype=torch.int32, device=self.device
),
seq_len_q=1, # TODO handle MTP which is not 1
)
if NSA_DECODE_IMPL == "flashmla_decode"
else None
),
}
def init_forward_metadata_capture_cuda_graph(
self,
bs: int,
num_tokens: int,
req_pool_indices: torch.Tensor,
seq_lens: torch.Tensor,
encoder_lens: Optional[torch.Tensor],
forward_mode: ForwardMode,
spec_info: Optional[SpecInput],
):
"""Initialize forward metadata for capturing CUDA graph."""
assert forward_mode.is_decode_or_idle(), "Only support decode for now"
assert (
spec_info is None
), "Speculative decoding is not supported for NSA backend now"
# Normal Decode
# Get sequence information
cache_seqlens_int32 = seq_lens.to(torch.int32)
cu_seqlens_k = compute_cu_seqlens(cache_seqlens_int32)
# Use max context length for seq_len_k
page_table_1 = self.decode_cuda_graph_metadata["page_table"][:bs, :]
max_seq_len_k = page_table_1.shape[1]
# Precompute page table
# Precompute cumulative sequence lengths
# NOTE(dark): this is always arange, since we are decoding
cu_seqlens_q = self.decode_cuda_graph_metadata["cu_seqlens_q"][: bs + 1]
nsa_cache_seqlens_int32 = compute_nsa_seqlens(
cache_seqlens_int32, nsa_index_topk=self.nsa_index_topk
)
nsa_cu_seqlens_k = compute_cu_seqlens(nsa_cache_seqlens_int32)
nsa_cu_seqlens_q = self.get_device_int32_arange(len(nsa_cu_seqlens_k))
real_page_table = self._transform_table_1_to_real(page_table_1)
if NSA_DECODE_IMPL == "flashmla_decode":
flashmla_metadata = self.decode_cuda_graph_metadata[
"flashmla_metadata"
].slice(slice(0, bs + 1))
flashmla_metadata.copy_(
self._compute_flashmla_metadata(
cache_seqlens=nsa_cache_seqlens_int32,
seq_len_q=1, # TODO handle MTP which is not 1
)
)
else:
flashmla_metadata = None
metadata = NSAMetadata(
page_size=self.real_page_size,
cache_seqlens_int32=cache_seqlens_int32,
max_seq_len_q=1,
max_seq_len_k=max_seq_len_k,
cu_seqlens_q=cu_seqlens_q,
cu_seqlens_k=cu_seqlens_k,
page_table_1=page_table_1,
flashmla_metadata=flashmla_metadata,
nsa_cache_seqlens_int32=nsa_cache_seqlens_int32,
nsa_cu_seqlens_q=nsa_cu_seqlens_q,
nsa_cu_seqlens_k=nsa_cu_seqlens_k,
nsa_seqlens_expanded=cache_seqlens_int32,
real_page_table=real_page_table,
nsa_extend_seq_lens_list=[1] * bs,
)
self.decode_cuda_graph_metadata[bs] = metadata
self.forward_metadata = metadata
def init_forward_metadata_replay_cuda_graph(
self,
bs: int,
req_pool_indices: torch.Tensor,
seq_lens: torch.Tensor,
seq_lens_sum: int,
encoder_lens: Optional[torch.Tensor],
forward_mode: ForwardMode,
spec_info: Optional[SpecInput],
seq_lens_cpu: Optional[torch.Tensor],
out_cache_loc: Optional[torch.Tensor] = None,
):
"""Initialize forward metadata for replaying CUDA graph."""
assert seq_lens_cpu is not None
assert forward_mode.is_decode_or_idle(), "Only support decode for now"
assert (
spec_info is None
), "Speculative decoding is not supported for NSA backend now"
seq_lens = seq_lens[:bs]
seq_lens_cpu = seq_lens_cpu[:bs]
req_pool_indices = req_pool_indices[:bs]
# Normal Decode
metadata: NSAMetadata = self.decode_cuda_graph_metadata[bs]
max_len = int(seq_lens_cpu.max().item())
cache_seqlens = seq_lens.to(torch.int32)
metadata.cache_seqlens_int32.copy_(cache_seqlens)
metadata.cu_seqlens_k[1:].copy_(
torch.cumsum(cache_seqlens, dim=0, dtype=torch.int32)
)
page_indices = self.req_to_token[req_pool_indices, :max_len]
metadata.page_table_1[:, :max_len].copy_(page_indices)
assert (
metadata.nsa_cache_seqlens_int32 is not None
and metadata.nsa_cu_seqlens_k is not None
and self.nsa_index_topk is not None
)
nsa_cache_seqlens = compute_nsa_seqlens(cache_seqlens, self.nsa_index_topk)
metadata.nsa_cache_seqlens_int32.copy_(nsa_cache_seqlens)
metadata.nsa_cu_seqlens_k[1:].copy_(
torch.cumsum(nsa_cache_seqlens, dim=0, dtype=torch.int32)
)
# NOTE(dark): (nsa-) cu_seqlens_q is always arange, no need to copy
assert self.real_page_size == metadata.page_size
if self.real_page_size > 1:
real_table = self._transform_table_1_to_real(page_indices)
new_len = real_table.shape[1]
metadata.real_page_table[:, :new_len].copy_(real_table)
else:
assert metadata.real_page_table is metadata.page_table_1
if NSA_DECODE_IMPL == "flashmla_decode":
metadata.flashmla_metadata.copy_(
self._compute_flashmla_metadata(
cache_seqlens=nsa_cache_seqlens,
seq_len_q=1, # TODO handle MTP which is not 1
)
)
self.forward_metadata = metadata
def forward_extend(
self,
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
layer: RadixAttention,
forward_batch: ForwardBatch,
save_kv_cache=True,
# For multi-head latent attention
q_rope: Optional[torch.Tensor] = None,
k_rope: Optional[torch.Tensor] = None,
topk_indices: Optional[torch.Tensor] = None,
) -> torch.Tensor:
assert (
not forward_batch.forward_mode.is_target_verify()
and not forward_batch.forward_mode.is_draft_extend()
), "NSA backend doesn't support speculative decoding"
if k is not None:
assert v is not None
if save_kv_cache:
cache_loc = (
forward_batch.out_cache_loc
if not layer.is_cross_attention
else forward_batch.encoder_out_cache_loc
)
forward_batch.token_to_kv_pool.set_mla_kv_buffer( # type: ignore
layer,
cache_loc,
k,
k_rope,
)
metadata = self.forward_metadata
causal = not layer.is_cross_attention
assert causal, "NSA is causal only"
# For fa3 interface version compatibility, we put new fields into conditional keyword args
kwargs = {}
# Do absorbed multi-latent attention
assert q_rope is not None
kv_cache = forward_batch.token_to_kv_pool.get_key_buffer(layer.layer_id)
# when store in fp8 and compute in fp8, no need to convert dtype
if not (
NSA_FLASHMLA_BACKEND_DECODE_COMPUTE_FP8 and self.nsa_kv_cache_store_fp8
):
kv_cache = kv_cache.to(q.dtype)
if q_rope is not None:
q_nope = q.view(-1, layer.tp_q_head_num, layer.v_head_dim)
q_rope = q_rope.view(
-1, layer.tp_q_head_num, layer.head_dim - layer.v_head_dim
)
else:
q_all = q.contiguous().view(-1, layer.tp_q_head_num, layer.head_dim)
q_nope = q_all[:, :, : layer.v_head_dim]
q_rope = q_all[:, :, layer.v_head_dim :]
# NOTE(dark): here, we use page size = 1
if NSA_FUSE_TOPK:
page_table_1 = topk_indices
else:
assert metadata.nsa_extend_seq_lens_list is not None
page_table_1 = transform_index_page_table_prefill(
page_table=metadata.page_table_1,
topk_indices=topk_indices,
extend_lens_cpu=metadata.nsa_extend_seq_lens_list,
page_size=1,
)
if NSA_PREFILL_IMPL == "tilelang":
if q_rope is not None:
q_all = torch.cat([q_nope, q_rope], dim=-1)
return self._forward_tilelang(
q_all=q_all,
kv_cache=kv_cache,
page_table_1=page_table_1,
sm_scale=layer.scaling,
v_head_dim=layer.v_head_dim,
)
elif NSA_PREFILL_IMPL == "flashmla_prefill":
if q_rope is not None:
q_all = torch.cat([q_nope, q_rope], dim=-1)
return self._forward_flashmla_prefill(
q_all=q_all,
kv_cache=kv_cache,
page_table_1=page_table_1,
sm_scale=layer.scaling,
v_head_dim=layer.v_head_dim,
)
elif NSA_PREFILL_IMPL == "flashmla_decode":
if q_rope is not None:
q_all = torch.cat([q_nope, q_rope], dim=-1)
return self._forward_flashmla_decode(
q_all=q_all,
kv_cache=kv_cache,
sm_scale=layer.scaling,
v_head_dim=layer.v_head_dim,
# TODO optimize args
layer=layer,
metadata=metadata,
page_table_1=page_table_1,
)
elif NSA_PREFILL_IMPL == "fa3":
return self._forward_fa3(
q_rope=q_rope,
kv_cache=kv_cache,
v_head_dim=layer.v_head_dim,
q_nope=q_nope,
page_table=page_table_1,
cache_seqlens=metadata.nsa_cache_seqlens_int32,
cu_seqlens_q=metadata.nsa_cu_seqlens_q,
cu_seqlens_k=metadata.nsa_cu_seqlens_k,
max_seqlen_q=metadata.nsa_max_seqlen_q,
sm_scale=layer.scaling,
logit_cap=layer.logit_cap,
page_size=1,
)
else:
raise ValueError(f"Unsupported {NSA_PREFILL_IMPL = }")
def forward_decode(
self,
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
layer: RadixAttention,
forward_batch: ForwardBatch,
save_kv_cache=True,
# For multi-head latent attention
q_rope: Optional[torch.Tensor] = None,
k_rope: Optional[torch.Tensor] = None,
topk_indices: Optional[torch.Tensor] = None,
) -> torch.Tensor:
if k is not None:
assert v is not None
if save_kv_cache:
cache_loc = (
forward_batch.out_cache_loc
if not layer.is_cross_attention
else forward_batch.encoder_out_cache_loc
)
forward_batch.token_to_kv_pool.set_mla_kv_buffer( # type: ignore
layer,
cache_loc,
k,
k_rope,
)
metadata = self.forward_metadata
causal = not layer.is_cross_attention
assert causal, "NSA is causal only"
# Do absorbed multi-latent attention
kv_cache = forward_batch.token_to_kv_pool.get_key_buffer(layer.layer_id)
if q_rope is not None:
q_nope = q.view(-1, layer.tp_q_head_num, layer.v_head_dim)
q_rope = q_rope.view(
-1, layer.tp_q_head_num, layer.head_dim - layer.v_head_dim
)
else:
q_all = q.contiguous().view(-1, layer.tp_q_head_num, layer.head_dim)
q_nope = q_all[:, :, : layer.v_head_dim]
q_rope = q_all[:, :, layer.v_head_dim :]
if NSA_FUSE_TOPK:
page_table_1 = topk_indices
else:
page_table_1 = transform_index_page_table_decode(
page_table=metadata.page_table_1,
topk_indices=topk_indices,
page_size=1,
)
if NSA_DECODE_IMPL == "flashmla_prefill":
if q_rope is not None:
q_all = torch.cat([q_nope, q_rope], dim=-1)
return self._forward_flashmla_prefill(
q_all=q_all,
kv_cache=kv_cache,
page_table_1=page_table_1,
sm_scale=layer.scaling,
v_head_dim=layer.v_head_dim,
)
elif NSA_DECODE_IMPL == "flashmla_decode":
if q_rope is not None:
q_all = torch.cat([q_nope, q_rope], dim=-1)
return self._forward_flashmla_decode(
q_all=q_all,
kv_cache=kv_cache,
sm_scale=layer.scaling,
v_head_dim=layer.v_head_dim,
# TODO optimize args
layer=layer,
metadata=metadata,
page_table_1=page_table_1,
)
elif NSA_DECODE_IMPL == "tilelang":
if q_rope is not None:
q_all = torch.cat([q_nope, q_rope], dim=-1)
return self._forward_tilelang(
q_all=q_all,
kv_cache=kv_cache,
page_table_1=page_table_1,
sm_scale=layer.scaling,
v_head_dim=layer.v_head_dim,
)
elif NSA_DECODE_IMPL == "fa3":
return self._forward_fa3(
q_rope=q_rope,
kv_cache=kv_cache,
v_head_dim=layer.v_head_dim,
q_nope=q_nope,
page_table=page_table_1,
cache_seqlens=metadata.nsa_cache_seqlens_int32,
cu_seqlens_q=metadata.nsa_cu_seqlens_q,
cu_seqlens_k=metadata.nsa_cu_seqlens_k,
max_seqlen_q=metadata.nsa_max_seqlen_q,
sm_scale=layer.scaling,
logit_cap=layer.logit_cap,
page_size=1,
)
elif NSA_DECODE_IMPL == "aiter":
if q_rope is not None:
q_all = torch.cat([q_nope, q_rope], dim=-1)
return self._forward_aiter(
q_all=q_all,
kv_cache=kv_cache,
page_table_1=page_table_1,
layer=layer,
metadata=metadata,
bs=forward_batch.batch_size,
)
else:
assert False, f"Unsupported {NSA_DECODE_IMPL = }"
def _forward_fa3(
self,
q_rope: torch.Tensor,
kv_cache: torch.Tensor,
v_head_dim: int,
q_nope: torch.Tensor,
page_table: torch.Tensor,
cache_seqlens: torch.Tensor,
cu_seqlens_q: torch.Tensor,
cu_seqlens_k: torch.Tensor,
max_seqlen_q: int,
sm_scale: float,
logit_cap: float,
page_size: int,
) -> torch.Tensor:
k_rope_cache = kv_cache[:, :, v_head_dim:]
c_kv_cache = kv_cache[:, :, :v_head_dim]
qk_rope_dim = k_rope_cache.shape[-1]
k_rope_cache = k_rope_cache.view(-1, page_size, 1, qk_rope_dim)
c_kv_cache = c_kv_cache.view(-1, page_size, 1, v_head_dim)
o = flash_attn_with_kvcache(
q=q_rope,
k_cache=k_rope_cache,
v_cache=c_kv_cache,
qv=q_nope,
page_table=page_table,
cache_seqlens=cache_seqlens,
cu_seqlens_q=cu_seqlens_q,
cu_seqlens_k_new=cu_seqlens_k,
max_seqlen_q=max_seqlen_q,
softmax_scale=sm_scale,
causal=True,
softcap=logit_cap,
return_softmax_lse=False,
num_splits=self.num_splits,
)
return o # type: ignore
def _forward_flashmla_prefill(
self,
q_all: torch.Tensor,
kv_cache: torch.Tensor,
v_head_dim: int,
page_table_1: torch.Tensor,
sm_scale: float,
) -> torch.Tensor:
from flash_mla import flash_mla_sparse_fwd
o, _, _ = flash_mla_sparse_fwd(
q=q_all,
kv=kv_cache,
indices=page_table_1.unsqueeze(1),
sm_scale=sm_scale,
d_v=v_head_dim,
)
return o
def _forward_flashmla_decode(
self,
q_all: torch.Tensor,
kv_cache: torch.Tensor,
v_head_dim: int,
sm_scale: float,
layer,
metadata: NSAMetadata,
page_table_1,
) -> torch.Tensor:
from flash_mla import flash_mla_with_kvcache
cache_seqlens = metadata.nsa_cache_seqlens_int32
# TODO the 2nd dim is seq_len_q, need to be >1 when MTP
q_all = q_all.view(-1, 1, layer.tp_q_head_num, layer.head_dim)
kv_cache = kv_cache.view(-1, self.real_page_size, 1, self.kv_cache_dim)
assert self.real_page_size == 64, "only page size 64 is supported"
if NSA_FLASHMLA_BACKEND_DECODE_COMPUTE_FP8 and not self.nsa_kv_cache_store_fp8:
# inefficiently quantize the whole cache
kv_cache = quantize_k_cache(kv_cache)
indices = page_table_1.unsqueeze(1)
assert (
indices.shape[-1] == self.nsa_index_topk
) # requirement of FlashMLA decode kernel
o, _ = flash_mla_with_kvcache(
q=q_all,
k_cache=kv_cache,
cache_seqlens=cache_seqlens,
head_dim_v=v_head_dim,
tile_scheduler_metadata=metadata.flashmla_metadata.flashmla_metadata,
num_splits=metadata.flashmla_metadata.num_splits,
softmax_scale=sm_scale,
indices=indices,
# doc says it is not used, but if pass in None then error
block_table=torch.empty(
(q_all.shape[0], 0), dtype=torch.int32, device=q_all.device
),
is_fp8_kvcache=NSA_FLASHMLA_BACKEND_DECODE_COMPUTE_FP8,
)
return o
def _forward_tilelang(
self,
q_all: torch.Tensor,
kv_cache: torch.Tensor,
v_head_dim: int,
page_table_1: torch.Tensor,
sm_scale: float,
) -> torch.Tensor:
from sglang.srt.layers.attention.nsa.tilelang_kernel import tilelang_sparse_fwd
return tilelang_sparse_fwd(
q=q_all,
kv=kv_cache,
indices=page_table_1.unsqueeze(1),
sm_scale=sm_scale,
d_v=v_head_dim,
)
def _forward_aiter(
self,
q_all: torch.Tensor,
kv_cache: torch.Tensor,
page_table_1: torch.Tensor,
layer: RadixAttention,
metadata: NSAMetadata,
bs: int,
) -> torch.Tensor:
q = q_all.reshape(-1, layer.tp_q_head_num * layer.head_dim)
if layer.head_dim != layer.v_head_dim:
o = q.new_empty((q.shape[0], layer.tp_q_head_num * layer.v_head_dim))
else:
o = torch.empty_like(q)
kv_indptr = self.kv_indptr
non_minus1_mask = page_table_1 != -1
non_minus1_counts = non_minus1_mask.sum(dim=1)
kv_indptr[1 : bs + 1] = torch.cumsum(non_minus1_counts, dim=0)
kv_indices = page_table_1[page_table_1 != -1]
mla_decode_fwd(
q.view(-1, layer.tp_q_head_num, layer.head_dim),
kv_cache.view(-1, 1, 1, layer.head_dim),
o.view(-1, layer.tp_q_head_num, layer.v_head_dim),
metadata.cu_seqlens_q,
kv_indptr,
kv_indices,
metadata.cu_seqlens_q,
metadata.max_seq_len_q,
layer.scaling,
layer.logit_cap,
)
# kv_cache = kv_cache.view(-1, 1, layer.head_dim)
return o
def get_cuda_graph_seq_len_fill_value(self):
"""Get the fill value for sequence length in CUDA graph."""
return 1
def get_indexer_metadata(
self, layer_id: int, forward_batch: ForwardBatch
) -> NSAIndexerMetadata:
return NSAIndexerMetadata(attn_metadata=self.forward_metadata)
def _compute_flashmla_metadata(self, cache_seqlens: torch.Tensor, seq_len_q: int):
from flash_mla import get_mla_metadata
flashmla_metadata, num_splits = get_mla_metadata(
cache_seqlens=cache_seqlens,
# TODO doc says `num_q_tokens_per_q_seq * num_heads_q // num_heads_k`
# but the name looks like need seq_len_q?
num_q_tokens_per_head_k=seq_len_q * self.num_q_heads // 1,
num_heads_k=1,
num_heads_q=self.num_q_heads,
is_fp8_kvcache=NSA_FLASHMLA_BACKEND_DECODE_COMPUTE_FP8,
topk=self.nsa_index_topk,
)
return NSAFlashMLAMetadata(
flashmla_metadata=flashmla_metadata,
num_splits=num_splits,
)