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Refactor and annotate types for attention

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This commit is contained in:
Woosuk Kwon 2023-02-24 08:58:46 +00:00
parent 7f22f90e8c
commit 762fd1c3fa
1 changed files with 40 additions and 32 deletions
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72
cacheflow/models/attention.py
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@ -1,4 +1,4 @@
from typing import Optional
from typing import List, Optional
import torch
import torch.nn as nn
@ -30,24 +30,34 @@ class OPTCacheFlowAttention(nn.Module):
def multi_query_kv_attention(
self,
output: torch.Tensor,
query: torch.Tensor,
key: torch.Tensor,
value: torch.Tensor,
output: torch.Tensor, # [num_prompt_tokens, num_heads, head_size]
query: torch.Tensor, # [num_prompt_tokens, num_heads, head_size]
key: torch.Tensor, # [num_prompt_tokens, num_heads, head_size]
value: torch.Tensor, # [num_prompt_tokens, num_heads, head_size]
prompt_lens: List[int],
) -> None:
# FIXME(woosuk): Replace this with a custom op call.
attention_mask = torch.triu(
torch.ones(query.shape[0], key.shape[0]), diagonal=1) * -1e5
attention_mask = attention_mask.to(dtype=query.dtype, device=query.device)
out = self._masked_attention(query, key, value, attention_mask)
output.copy_(out, non_blocking=True)
# FIXME(woosuk): Replace the following with a custom op.
start_idx = 0
for prompt_len in prompt_lens:
out = output[start_idx:start_idx + prompt_len]
q = query[start_idx:start_idx + prompt_len]
k = key[start_idx:start_idx + prompt_len]
v = value[start_idx:start_idx + prompt_len]
attention_mask = torch.triu(
torch.ones(q.shape[0], k.shape[0]), diagonal=1) * -1e5
attention_mask = attention_mask.to(dtype=q.dtype, device=q.device)
attention_out = self._masked_attention(q, k, v, attention_mask)
out.copy_(attention_out, non_blocking=True)
start_idx += prompt_len
def single_query_cached_kv_attention(
self,
output: torch.Tensor,
query: torch.Tensor,
key_cache: torch.Tensor,
value_cache: torch.Tensor,
output: torch.Tensor, # [num_generation_tokens, num_heads, head_size]
query: torch.Tensor, # [num_generation_tokens, num_heads, head_size]
key_cache: torch.Tensor, # [num_blocks, num_heads, head_size/x, block_size, x]
value_cache: torch.Tensor, # [num_blocks, num_heads, block_size, head_size]
input_metadata: InputMetadata,
) -> None:
num_heads = value_cache.shape[1]
@ -82,15 +92,18 @@ class OPTCacheFlowAttention(nn.Module):
def forward(
self,
query: torch.Tensor,
key: torch.Tensor,
value: torch.Tensor,
key_cache: torch.Tensor,
value_cache: torch.Tensor,
query: torch.Tensor, # [num_tokens, num_heads * head_size]
key: torch.Tensor, # [num_tokens, num_heads * head_size]
value: torch.Tensor, # [num_tokens, num_heads * head_size]
key_cache: torch.Tensor, # [num_blocks, num_heads, head_size/x, block_size, x]
value_cache: torch.Tensor, # [num_blocks, num_heads, block_size, head_size]
input_metadata: InputMetadata,
cache_event: Optional[torch.cuda.Event],
) -> torch.Tensor:
# Prune out invalid tokens.
) -> torch.Tensor: # [num_tokens, num_heads * head_size]
# Pre-allocate the output tensor.
output = torch.empty_like(query)
# Prune out paddings if any.
query = query[:input_metadata.num_valid_tokens]
key = key[:input_metadata.num_valid_tokens]
value = value[:input_metadata.num_valid_tokens]
@ -101,18 +114,11 @@ class OPTCacheFlowAttention(nn.Module):
query = query.view(-1, num_heads, head_size)
key = key.view(-1, num_heads, head_size)
value = value.view(-1, num_heads, head_size)
output = output.view(-1, num_heads, head_size)
# Compute the attention op for prompts.
output = torch.empty_like(query)
start_idx = 0
for i in range(input_metadata.num_prompts):
prompt_len = input_metadata.prompt_lens[i]
out = output[start_idx:start_idx + prompt_len]
q = query[start_idx:start_idx + prompt_len]
k = key[start_idx:start_idx + prompt_len]
v = value[start_idx:start_idx + prompt_len]
self.multi_query_kv_attention(out, q, k, v)
start_idx += prompt_len
self.multi_query_kv_attention(
output, query, key, value, input_metadata.prompt_lens)
# Wait until the cache op is done.
if cache_event is not None:
@ -124,6 +130,7 @@ class OPTCacheFlowAttention(nn.Module):
if input_metadata.num_generation_tokens > 0:
# Compute the attention op for generation tokens.
start_idx = sum(input_metadata.prompt_lens)
self.single_query_cached_kv_attention(
output[start_idx:],
query[start_idx:],
@ -132,4 +139,5 @@ class OPTCacheFlowAttention(nn.Module):
input_metadata)
# Reshape the output tensor.
# NOTE(woosuk): The output tensor may include paddings.
return output.view(-1, num_heads * head_size)