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[BugFix] fix prefixcache performance and accuracy on ascend (#13573)

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This commit is contained in:
khalilzhk
2025-12-08 02:16:20 +08:00
committed by GitHub
parent f124539a01
commit 948b6acee8
5 changed files with 289 additions and 28 deletions
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python/sglang/srt/hardware_backend/npu/attention/ascend_backend.py
+131 -6
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@@ -43,9 +43,13 @@ class ForwardMetadata:
seq_lens: Optional[torch.Tensor] = None
actual_seq_lengths_q: Optional[torch.Tensor] = None
# prefix cache
prefix_lens: Optional[torch.Tensor] = None
flatten_prefix_block_tables: Optional[torch.Tensor] = None
class AscendAttnMaskBuilder:
def __init__(self, model_runner: ModelRunner, device, use_fia):
def __init__(self, model_runner: ModelRunner, device, use_fia, use_mla):
"""
Initialize the AscendAttnMaskBuilder class.
@@ -76,6 +80,13 @@ class AscendAttnMaskBuilder:
self.mix_mask_cache = self.generate_attn_mask(mixed_chunk_cache_len, "mix")
self.mix_seq_len_cached = self.mix_mask_cache.shape[0]
if use_mla:
# Initialize RingMla mask
ringmla_mask_len = 512
self.ringmla_mask = self.generate_attn_mask(
ringmla_mask_len, "norm", torch.bfloat16
).to(self.device)
@staticmethod
def generate_mask_flag(max_seq_len):
"""
@@ -216,6 +227,7 @@ class AscendAttnBackend(AttentionBackend):
if self.use_mla:
self.kv_lora_rank = model_runner.model_config.kv_lora_rank
self.qk_rope_head_dim = model_runner.model_config.qk_rope_head_dim
self.qk_nope_head_dim = model_runner.model_config.qk_nope_head_dim
self.q_head_dim = (
self.qk_rope_head_dim + model_runner.model_config.qk_nope_head_dim
)
@@ -229,7 +241,7 @@ class AscendAttnBackend(AttentionBackend):
model_runner.server_args.speculative_num_draft_tokens
)
self.ascend_attn_mask_builder = AscendAttnMaskBuilder(
model_runner, self.device, self.use_fia
model_runner, self.device, self.use_fia, self.use_mla
)
self.mask, self.fia_mask, self.mtp_mask, self.mix_mask = (
self.ascend_attn_mask_builder.mask,
@@ -237,6 +249,8 @@ class AscendAttnBackend(AttentionBackend):
self.ascend_attn_mask_builder.mtp_mask,
self.ascend_attn_mask_builder.mix_mask_cache,
)
if self.use_mla:
self.ringmla_mask = self.ascend_attn_mask_builder.ringmla_mask
def get_verify_buffers_to_fill_after_draft(self):
"""
@@ -279,6 +293,33 @@ class AscendAttnBackend(AttentionBackend):
if forward_batch.forward_mode.is_target_verify():
self.forward_metadata.seq_lens_cpu_int += self.speculative_num_draft_tokens
if (
self.use_mla
and forward_batch.forward_mode.is_extend()
and sum(forward_batch.extend_prefix_lens_cpu) > 0
):
self.forward_metadata.prefix_lens = forward_batch.extend_prefix_lens.to(
"cpu"
)
seq_prefix_lens = self.forward_metadata.prefix_lens.tolist()
self.forward_metadata.flatten_prefix_block_tables = torch.empty(
0, dtype=torch.int32
).to(self.device)
for req_idx, seq_len in zip(
forward_batch.req_pool_indices.tolist(), seq_prefix_lens
):
req_indices = forward_batch.req_to_token_pool.req_to_token[req_idx]
req_prefix_block_tables = (
req_indices[:seq_len][:: self.page_size] // self.page_size
)
self.forward_metadata.flatten_prefix_block_tables = torch.cat(
(
self.forward_metadata.flatten_prefix_block_tables,
torch.flatten(req_prefix_block_tables),
)
)
if forward_batch.forward_mode.is_mixed():
self.mix_mask = self.ascend_attn_mask_builder.update_mask(
self.forward_metadata
@@ -590,15 +631,99 @@ class AscendAttnBackend(AttentionBackend):
enable_gqa=use_gqa,
causal=causal,
)
elif sum(forward_batch.extend_prefix_lens_cpu) > 0:
q, k, v = [
data[: forward_batch.num_token_non_padded_cpu] for data in [q, k, v]
]
q_nope, q_rope = q.split([layer.v_head_dim, self.qk_rope_head_dim], dim=-1)
k_nope, k_rope = k.split([layer.v_head_dim, self.qk_rope_head_dim], dim=-1)
# 1st, compute extend tokens to get attn_output and attn_lse
num_tokens = q_nope.size(0)
attn_output = torch.zeros(
num_tokens,
layer.tp_q_head_num,
layer.v_head_dim,
dtype=q_nope.dtype,
device=q_nope.device,
)
attn_lse = torch.zeros(
layer.tp_q_head_num,
num_tokens,
dtype=torch.float32,
device=q_nope.device,
)
torch_npu.atb.npu_ring_mla(
q_nope=q_nope,
q_rope=q_rope,
k_nope=k_nope,
k_rope=k_rope,
value=v,
mask=self.ringmla_mask,
seqlen=self.forward_metadata.extend_seq_lens_cpu_int,
head_num=layer.tp_q_head_num,
kv_head_num=layer.tp_k_head_num,
pre_out=None,
prev_lse=None,
qk_scale=layer.scaling,
kernel_type="kernel_type_high_precision",
mask_type="mask_type_triu",
calc_type="calc_type_first_ring",
output=attn_output,
softmax_lse=attn_lse,
)
# 2nd, load history kvcache(kv_a and k_pe) and calculate k_nope
k_buffer = forward_batch.token_to_kv_pool.get_key_buffer(layer.layer_id)
v_buffer = forward_batch.token_to_kv_pool.get_value_buffer(layer.layer_id)
kv_cached = torch.index_select(
k_buffer, 0, self.forward_metadata.flatten_prefix_block_tables
)
k_rope_cached = torch.index_select(
v_buffer, 0, self.forward_metadata.flatten_prefix_block_tables
).flatten(0, 1)
assert layer.kv_b_proj is not None
kv = layer.kv_b_proj(kv_cached)[0].view(
-1, layer.tp_k_head_num, self.qk_nope_head_dim + layer.v_head_dim
)
k_nope, v = kv.split([self.qk_nope_head_dim, layer.v_head_dim], dim=-1)
# 3rd, compute history kv to attn_out
k_rope = k_rope_cached.expand(-1, layer.tp_k_head_num, -1)
seq_len = torch.stack(
[
self.forward_metadata.extend_seq_lens_cpu_int,
self.forward_metadata.prefix_lens,
]
)
torch_npu.atb.npu_ring_mla(
q_nope=q_nope,
q_rope=q_rope,
k_nope=k_nope,
k_rope=k_rope,
value=v,
mask=self.ringmla_mask,
seqlen=seq_len,
head_num=layer.tp_q_head_num,
kv_head_num=layer.tp_k_head_num,
pre_out=attn_output,
prev_lse=attn_lse,
qk_scale=layer.scaling,
kernel_type="kernel_type_high_precision",
mask_type="no_mask",
calc_type="calc_type_default",
output=attn_output,
softmax_lse=attn_lse,
)
attn_output = attn_output.reshape(
[-1, layer.tp_q_head_num, layer.v_head_dim]
)
else:
assert (
layer.qk_head_dim != layer.v_head_dim
), "FIA only supports qk_head_dim != v_head_dim"
# Wait for the KV transfer to complete before performing attention computation.
forward_batch.token_to_kv_pool.get_key_buffer(layer.layer_id)
forward_batch.token_to_kv_pool.get_value_buffer(layer.layer_id)
num_token_padding = q.shape[0]
q, k, v = [
data[: forward_batch.num_token_non_padded_cpu] for data in [q, k, v]