171 lines
5.5 KiB
Python
171 lines
5.5 KiB
Python
import unittest
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import sgl_kernel
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import torch
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from torch.nn.functional import scaled_dot_product_attention
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from sglang.test.test_utils import CustomTestCase
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torch.manual_seed(1234)
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class TestDecodeAttention(CustomTestCase):
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def _run_sdpa_forward_decode(
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self,
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query: torch.Tensor,
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output: torch.Tensor,
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k_cache: torch.Tensor,
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v_cache: torch.Tensor,
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req_to_token: torch.Tensor,
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req_pool_indices: torch.Tensor,
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seq_lens: torch.Tensor,
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scaling=None,
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enable_gqa=False,
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causal=False,
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):
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# [num_tokens, num_heads, head_size] -> [num_heads, num_tokens, head_size]
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query = query.movedim(0, query.dim() - 2)
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start_q, start_kv = 0, 0
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for seq_idx in range(seq_lens.shape[0]):
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seq_len_q = 1
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seq_len_kv = seq_lens[seq_idx]
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end_q = start_q + seq_len_q
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end_kv = start_kv + seq_len_kv
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per_req_query = query[:, start_q:end_q, :]
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# get key and value from cache. per_req_tokens contains the kv cache
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# index for each token in the sequence.
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req_pool_idx = req_pool_indices[seq_idx]
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per_req_tokens = req_to_token[req_pool_idx, :seq_len_kv]
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per_req_key = k_cache[per_req_tokens].movedim(0, query.dim() - 2)
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per_req_value = v_cache[per_req_tokens].movedim(0, query.dim() - 2)
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per_req_out = (
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scaled_dot_product_attention(
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per_req_query.unsqueeze(0),
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per_req_key.unsqueeze(0),
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per_req_value.unsqueeze(0),
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enable_gqa=enable_gqa,
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scale=scaling,
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is_causal=causal,
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)
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.squeeze(0)
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.movedim(query.dim() - 2, 0)
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)
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output[start_q:end_q, :, :] = per_req_out
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start_q, start_kv = end_q, end_kv
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return output
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def _test_grouped_decode_attention_once(self, B, H_Q, H_KV, D, D_V, device):
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dtype = torch.bfloat16
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# This represents the number of tokens already in the sequence
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seq_len = 1024
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total_tokens = B * seq_len
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sm_scale = 1.0 / (D**0.5)
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logit_cap = 0.0
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num_kv_splits = 8
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enable_gqa = H_Q != H_KV
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# q represents the new token being generated, one per batch
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q = torch.randn(B, H_Q, D, dtype=dtype, device=device)
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# k_buffer and v_buffer represent all previous tokens
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k_buffer = torch.randn(total_tokens, H_KV, D, dtype=dtype, device=device)
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v_buffer = torch.randn(total_tokens, H_KV, D_V, dtype=dtype, device=device)
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key = torch.randn(B, H_KV, D, dtype=dtype)
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value = torch.randn(B, H_KV, D_V, dtype=dtype)
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loc = torch.randint(0, 10, (B,)).to(torch.int64)
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# set kv cache
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k_buffer[loc] = key
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v_buffer[loc] = value
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# o will have the same shape as q
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o = torch.zeros(B, H_Q, D_V, dtype=dtype, device=device)
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o_grouped = torch.zeros(B, H_Q, D_V, dtype=dtype, device=device)
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req_to_token = (
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torch.arange(total_tokens, device=device)
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.reshape(B, seq_len)
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.to(torch.int32)
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)
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b_req_idx = torch.arange(B, device=device).to(torch.int64)
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b_seq_len = torch.full((B,), seq_len, device=device).to(torch.int64)
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attn_logits = torch.empty(
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(B, H_Q, num_kv_splits, D_V + 1),
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dtype=torch.float32,
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device=device,
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)
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# k_buffer, v_buffer, query, key and value supports non-contiguous tensors
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k_buffer = k_buffer.transpose(0, 1).contiguous().transpose(0, 1)
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v_buffer = v_buffer.transpose(0, 1).contiguous().transpose(0, 1)
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q = q.transpose(0, 1).contiguous().transpose(0, 1)
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key = key.transpose(0, 1).contiguous().transpose(0, 1)
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value = value.transpose(0, 1).contiguous().transpose(0, 1)
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torch.ops.sgl_kernel.decode_attention_cpu(
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q,
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k_buffer,
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v_buffer,
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o,
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key,
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value,
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loc,
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attn_logits,
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req_to_token,
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b_req_idx,
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b_seq_len,
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sm_scale,
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logit_cap,
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)
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self._run_sdpa_forward_decode(
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q,
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o_grouped,
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k_buffer,
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v_buffer,
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req_to_token,
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b_req_idx,
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b_seq_len,
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scaling=sm_scale,
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enable_gqa=enable_gqa,
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)
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cos_sim = torch.nn.functional.cosine_similarity(
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o.flatten(), o_grouped.flatten(), dim=0
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)
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self.assertGreater(cos_sim.item(), 0.99)
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torch.testing.assert_close(o, o_grouped, atol=3e-2, rtol=1e-6)
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def _test_grouped_decode_attention(self, device="cuda"):
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configs = [
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(2, 16, 16, 64, 64),
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(2, 16, 1, 16, 16),
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(2, 32, 8, 33, 55),
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(2, 16, 1, 64, 64),
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(2, 64, 1, 13, 13),
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(2, 128, 1, 80, 80),
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(2, 128, 2, 512, 512),
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(1, 16, 1, 576, 512),
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(1, 16, 16, 576, 512),
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(1, 22, 1, 576, 512),
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(1, 40, 8, 128, 128),
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]
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for B, H_Q, H_KV, D, D_V in configs:
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self._test_grouped_decode_attention_once(
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B, H_Q, H_KV, D, D_V, device=device
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)
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def test_grouped_decode_attention(self):
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self._test_grouped_decode_attention("cpu")
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if __name__ == "__main__":
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unittest.main()
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