vllm/tests/kernels/test_cutlass_mla_decode.py

97 lines
3.4 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import pytest
import torch
import torch.nn.functional as F
from torch import Tensor
import vllm._custom_ops as ops
from vllm.platforms import current_platform
if not current_platform.has_device_capability(100):
pytest.skip(
reason="Cutlass MLA Requires compute capability of 10 or above.",
allow_module_level=True)
def ref_mla(
out: Tensor, # (bs, num_heads, v_head_dim)
query: Tensor, # (bs, num_heads, head_dim)
kv_cache: Tensor, # (num_blocks, block_size, head_dim)
scale: float,
block_tables: Tensor, # (bs, max_num_blocks)
seq_lens: Tensor, # (bs,)
):
bs, num_heads, v_head_dim = out.shape
head_dim = query.shape[2]
for i in range(bs):
# gather and flatten KV-cache
kv = kv_cache[
block_tables[i]] # (max_num_blocks, block_size, head_dim)
kv = kv.view(1, -1,
head_dim)[:, :seq_lens[i]] # (1, seq_len, head_dim)
v = kv[:, :, :v_head_dim]
q = query[i].view(num_heads, 1, head_dim)
o = F.scaled_dot_product_attention(q,
kv,
v,
scale=scale,
enable_gqa=True)
out[i] = o.view(num_heads, v_head_dim)
return out
@pytest.mark.parametrize("dtype", [torch.bfloat16, torch.float16])
@pytest.mark.parametrize("mean_seq_len", [128, 1024, 4096])
@pytest.mark.parametrize("bs", [1, 2, 4])
@pytest.mark.parametrize("varlen", [False, True])
@pytest.mark.parametrize("block_size", [16, 64, 128])
def test_cutlass_mla_decode(dtype: torch.dtype, mean_seq_len: int, bs: int,
varlen: bool, block_size: int):
torch.set_default_dtype(dtype)
torch.set_default_device('cuda')
torch.manual_seed(42)
d = 576
h_q = 128
dv = 512
q_nope_dim = 128
q_pe_dim = 64
scale = (q_nope_dim + q_pe_dim)**(-0.5)
if varlen:
seq_lens = torch.empty(bs).normal_(mean_seq_len, mean_seq_len / 2)
seq_lens = seq_lens.clip(2).to(torch.int32)
else:
seq_lens = torch.full((bs, ), mean_seq_len, dtype=torch.int32)
max_seq_len = seq_lens.max().item()
block_num = (max_seq_len + block_size - 1) // block_size
# Pad block_num so that small blocks can be packed into full 128-sized
# CUTLASS tiles. One 128-wide tile can hold (128 // block_size) small
# blocks.
pack_factor = 128 // block_size
block_num = ((block_num + pack_factor - 1) // pack_factor) * pack_factor
# Amplify input values to ensure test coverage of edge cases where CUTLASS
# kernel errors occur with split_k settings.
q = torch.randn(bs, h_q, d) * 100
block_table = torch.randint(0,
bs * block_num, (bs, block_num),
dtype=torch.int32)
kv_cache = torch.randn(block_table.numel(), block_size, d)
out_ref = q.new_zeros(bs, h_q, dv)
ref_mla(out_ref, q, kv_cache, scale, block_table, seq_lens)
out_ans = torch.zeros_like(out_ref)
q_nope = q[:, :, :dv].clone()
q_pe = q[:, :, dv:].clone()
ops.cutlass_mla_decode(out_ans, q_nope, q_pe, kv_cache, seq_lens,
block_table, scale)
torch.testing.assert_close(out_ans, out_ref, atol=1e-2, rtol=1e-2)