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sglang/test/srt/lora/test_chunked_sgmv_backend.py
2025-09-22 16:09:58 +08:00

762 lines
27 KiB
Python

import random
import unittest
from enum import Enum
from typing import Dict, List, Optional, Tuple
import torch
from sglang.srt.lora.backend.chunked_backend import ChunkedSgmvLoRABackend
from sglang.srt.lora.triton_ops import (
chunked_sgmv_lora_expand_forward,
chunked_sgmv_lora_shrink_forward,
)
from sglang.srt.lora.triton_ops.chunked_sgmv_expand import _chunked_lora_expand_kernel
from sglang.srt.lora.triton_ops.chunked_sgmv_shrink import _chunked_lora_shrink_kernel
from sglang.srt.lora.utils import LoRABatchInfo
CHUNK_SIZE = 16
def reset_kernel_cache():
_chunked_lora_shrink_kernel._clear_cache()
_chunked_lora_expand_kernel._clear_cache()
def safe_matmul(a: torch.Tensor, b: torch.Tensor) -> torch.Tensor:
"""Matrix multiplication with mixed precision handling for float16"""
result = torch.matmul(a.float(), b.float())
return result.to(a.dtype)
class BatchComposition(Enum):
UNIFORM = "uniform"
MIXED = "mixed"
SKEWED = "skewed"
NONE = "_NO_LORA_"
class BatchMode(Enum):
PREFILL = "prefill"
DECODE = "decode"
def reference_sgmv_shrink(
x: torch.Tensor,
weights: torch.Tensor,
batch_info: LoRABatchInfo,
seq_lengths: List[int],
lora_assignments: List[str],
num_slices: int = 1,
) -> torch.Tensor:
"""
Simple sequence-level reference implementation of SGMV shrink operation.
Args:
x: (total_seq_len, input_dim) - Input activations
weights: (num_loras, num_slices * max_rank, input_dim) - LoRA A weights
batch_info: Batch information (only used for lora_ranks)
seq_lengths: Length of each sequence
lora_assignments: LoRA name for each sequence
num_slices: Number of slices (3 for QKV, 2 for gate_up, 1 for others)
Returns:
output: (total_seq_len, num_slices * max_rank) - Intermediate activations
"""
if weights.numel() == 0:
total_seq_len = x.shape[0]
return torch.zeros(total_seq_len, 0, dtype=x.dtype, device=x.device)
total_seq_len, input_dim = x.shape
num_loras, weight_out_dim, _ = weights.shape
max_rank = weight_out_dim // num_slices
output = torch.zeros(
total_seq_len, num_slices * max_rank, dtype=x.dtype, device=x.device
)
unique_loras = sorted(set(lora_assignments))
lora_name_to_idx = {name: idx for idx, name in enumerate(unique_loras)}
lora_ranks = batch_info.lora_ranks.cpu().numpy()
token_offset = 0
for seq_len, lora_name in zip(seq_lengths, lora_assignments):
if seq_len == 0:
continue
lora_idx = lora_name_to_idx[lora_name]
rank = lora_ranks[lora_idx]
if rank > 0:
x_seq = x[token_offset : token_offset + seq_len, :]
w_seq = weights[lora_idx, : num_slices * rank, :]
result = safe_matmul(x_seq, w_seq.t())
output[token_offset : token_offset + seq_len, : num_slices * rank] = result
token_offset += seq_len
return output
def reference_sgmv_expand(
x: torch.Tensor,
weights: torch.Tensor,
batch_info: LoRABatchInfo,
seq_lengths: List[int],
lora_assignments: List[str],
slice_offsets: torch.Tensor,
max_slice_size: int,
base_output: Optional[torch.Tensor] = None,
) -> torch.Tensor:
"""
Simple sequence-level reference implementation of SGMV expand operation.
Args:
x: (total_seq_len, num_slices * max_rank) - Intermediate activations
weights: (num_loras, output_dim, max_rank) - LoRA B weights
batch_info: Batch information (only used for lora_ranks)
seq_lengths: Length of each sequence
lora_assignments: LoRA name for each sequence
slice_offsets: Tensor defining slice boundaries
max_slice_size: Maximum slice size for chunking
base_output: Optional base output to accumulate into
Returns:
output: (total_seq_len, total_output_dim) - Final output
"""
if weights.numel() == 0:
total_seq_len = x.shape[0]
total_output_dim = slice_offsets[-1].item() if len(slice_offsets) > 0 else 0
return torch.zeros(
total_seq_len, total_output_dim, dtype=x.dtype, device=x.device
)
total_seq_len, _ = x.shape
num_slices = len(slice_offsets) - 1
if base_output is not None:
output = base_output.clone()
else:
total_output_dim = slice_offsets[-1].item()
output = torch.zeros(
total_seq_len, total_output_dim, dtype=x.dtype, device=x.device
)
unique_loras = sorted(set(lora_assignments))
lora_name_to_idx = {name: idx for idx, name in enumerate(unique_loras)}
lora_ranks = batch_info.lora_ranks.cpu().numpy()
token_offset = 0
for seq_len, lora_name in zip(seq_lengths, lora_assignments):
if seq_len == 0:
continue
lora_idx = lora_name_to_idx[lora_name]
lora_rank = lora_ranks[lora_idx]
if lora_rank > 0:
# Extract sequence intermediate activations
x_seq = x[
token_offset : token_offset + seq_len, : num_slices * lora_rank
] # (seq_len, num_slices * rank)
for slice_idx in range(num_slices):
slice_start_input = slice_idx * lora_rank
slice_end_input = (slice_idx + 1) * lora_rank
slice_start_output = slice_offsets[slice_idx].item()
slice_end_output = slice_offsets[slice_idx + 1].item()
x_slice = x_seq[:, slice_start_input:slice_end_input] # (seq_len, rank)
w_slice = weights[
lora_idx, slice_start_output:slice_end_output, :lora_rank
] # (slice_dim, rank)
result = safe_matmul(x_slice, w_slice.t()) # (seq_len, slice_dim)
output[
token_offset : token_offset + seq_len,
slice_start_output:slice_end_output,
] += result
token_offset += seq_len
return output
class TestChunkedSGMV(unittest.TestCase):
# Test configuration constants
RTOL = 1e-3
ATOL = 1e-3
DEFAULT_BATCH_SIZE = 8
def _compare_shrink_outputs(
self,
chunked_output: torch.Tensor,
reference_output: torch.Tensor,
seq_lengths: List[int],
lora_assignments: List[str],
batch_info: LoRABatchInfo,
num_slices: int,
test_name: str,
):
"""
Compare only the valid portions of shrink outputs.
The chunked SGMV shrink kernel only guarantees correctness for
output[seq_start:seq_end, :rank * num_slices] for each sequence.
"""
# Create mapping from LoRA names to indices and ranks
unique_loras = sorted(set(lora_assignments))
lora_name_to_idx = {name: idx for idx, name in enumerate(unique_loras)}
lora_ranks = batch_info.lora_ranks.cpu().numpy()
token_offset = 0
for seq_idx, (seq_len, lora_name) in enumerate(
zip(seq_lengths, lora_assignments)
):
if seq_len == 0:
continue
lora_idx = lora_name_to_idx[lora_name]
rank = lora_ranks[lora_idx]
if rank > 0:
# Only compare the valid columns for this sequence
valid_cols = num_slices * rank
chunked_seq = chunked_output[
token_offset : token_offset + seq_len, :valid_cols
]
reference_seq = reference_output[
token_offset : token_offset + seq_len, :valid_cols
]
torch.testing.assert_close(
chunked_seq,
reference_seq,
rtol=self.RTOL,
atol=self.ATOL,
msg=f"Shrink operation failed for {test_name}, sequence {seq_idx} ({lora_name})",
)
token_offset += seq_len
def setUp(self):
"""Set up common test parameters"""
torch.manual_seed(42)
random.seed(42)
self.device = torch.device("cuda")
self.dtype = torch.float16
self.input_dim = 2560 # Hidden dimension
self.max_seq_len = 1024
# LoRA configurations: name -> (rank, output_q, output_k, output_v)
self.lora_configs = {
"lora_A": (8, 4096, 1024, 1024),
"lora_B": (16, 4096, 1024, 1024),
"lora_C": (32, 4096, 1024, 1024),
"_NO_LORA_": (0, 4096, 1024, 1024),
}
# QKV slice offsets: 4096 (Q) + 1024 (K) + 1024 (V) = 6144 total
self.slice_offsets = torch.tensor(
[0, 4096, 5120, 6144], dtype=torch.int32, device=self.device
)
self.max_slice_size = 4096
def generate_sequence_lengths(
self,
batch_size: int,
batch_mode: BatchMode = BatchMode.PREFILL,
min_len: int = 1,
max_len: int = None,
) -> List[int]:
"""Generate sequence lengths for a batch based on mode"""
if batch_mode == BatchMode.DECODE:
return [1] * batch_size
else:
if max_len is None:
max_len = self.max_seq_len
return [random.randint(min_len, max_len) for _ in range(batch_size)]
def create_lora_weights(
self, lora_name: str, include_missing_k: bool = False
) -> Tuple[torch.Tensor, torch.Tensor]:
"""Create LoRA A and B weights for given configuration"""
rank, out_q, out_k, out_v = self.lora_configs[lora_name]
if rank == 0:
lora_a = torch.empty(
0, self.input_dim, dtype=self.dtype, device=self.device
)
lora_b = torch.empty(
out_q + out_k + out_v, 0, dtype=self.dtype, device=self.device
)
return lora_a, lora_b
# Create LoRA A weights (3 slices for QKV)
lora_a = torch.randn(
3 * rank, self.input_dim, dtype=self.dtype, device=self.device
)
if include_missing_k:
lora_a[rank : 2 * rank, :] = 0.0
# Create LoRA B weights (stacked Q, K, V)
total_output_dim = out_q + out_k + out_v
lora_b = torch.randn(
total_output_dim, rank, dtype=self.dtype, device=self.device
)
if include_missing_k:
lora_b[out_q : out_q + out_k, :] = 0.0
return lora_a, lora_b
def create_batch_info(
self,
seq_lengths: List[int],
lora_assignments: List[Optional[str]],
batch_mode: BatchMode = BatchMode.PREFILL,
) -> LoRABatchInfo:
"""Create LoRABatchInfo using the same logic as chunked backend"""
unique_loras = sorted(set(lora_assignments))
lora_name_to_idx = {name: idx for idx, name in enumerate(unique_loras)}
seq_weight_indices = [lora_name_to_idx[name] for name in lora_assignments]
lora_ranks = [self.lora_configs[name][0] for name in unique_loras]
def create_mock_batch():
# Create a minimal mock ForwardBatch for the test
class MockForwardBatch:
def __init__(self, batch_size, seq_lengths):
self.batch_size = batch_size
self.extend_seq_lens_cpu = seq_lengths
self.forward_mode = MockForwardMode()
class MockForwardMode:
def is_extend(self):
return batch_mode == BatchMode.PREFILL
return MockForwardBatch(len(seq_lengths), seq_lengths)
mock_batch = create_mock_batch()
# Use the same functions as chunked backend
permutation, weights_reordered = ChunkedSgmvLoRABackend._get_permutation(
seq_weight_indices, mock_batch
)
# Create a minimal backend instance to access _get_segments_info
mock_server_args = type(
"ServerArgs", (object,), {"max_lora_chunk_size": "MOCK_NEVER_USED"}
)
mock_backend = ChunkedSgmvLoRABackend(
max_loras_per_batch=8, device=self.device, server_args=mock_server_args
)
weight_indices_list, seg_indptr = mock_backend._get_segments_info(
weights_reordered,
chunk_size=CHUNK_SIZE,
)
scalings = [1.0] * len(unique_loras)
seg_indptr_tensor = seg_indptr.to(self.device)
weight_indices_tensor = weight_indices_list.to(self.device)
lora_ranks_tensor = (
torch.tensor(lora_ranks, dtype=torch.int32, device=self.device)
if lora_ranks
else torch.empty(0, dtype=torch.int32, device=self.device)
)
scalings_tensor = (
torch.tensor(scalings, dtype=torch.float32, device=self.device)
if scalings
else torch.empty(0, dtype=torch.float32, device=self.device)
)
permutation_tensor = permutation.to(
self.device, dtype=torch.int32
) # Convert to int32 for LoRABatchInfo
seq_lens_tensor = torch.tensor(
seq_lengths, dtype=torch.int32, device=self.device
)
return LoRABatchInfo(
use_cuda_graph=False,
bs=len(seq_lengths),
num_segments=len(weight_indices_list), # Number of segments, not sequences!
seg_indptr=seg_indptr_tensor,
weight_indices=weight_indices_tensor,
lora_ranks=lora_ranks_tensor,
scalings=scalings_tensor,
seg_lens=seq_lens_tensor, # Original sequence lengths for reference
max_len=CHUNK_SIZE,
permutation=permutation_tensor, # Token reordering permutation
)
def stack_lora_weights(
self, weight_list: List[torch.Tensor], is_lora_a: bool
) -> torch.Tensor:
"""Stack LoRA weights from different adapters into a single tensor"""
if not weight_list:
return torch.empty(0, 0, 0, dtype=self.dtype, device=self.device)
first_non_empty = next((w for w in weight_list if w.numel() > 0), None)
if first_non_empty is None:
return torch.empty(
len(weight_list), 0, 0, dtype=self.dtype, device=self.device
)
if is_lora_a:
# LoRA A: (slice_num * rank, input_dim) -> (num_loras, slice_num * max_rank, input_dim)
max_rank = max(w.shape[0] // 3 if w.numel() > 0 else 0 for w in weight_list)
final_shape = (len(weight_list), 3 * max_rank, self.input_dim)
else:
# LoRA B: (output_dim, rank) -> (num_loras, output_dim, max_rank)
max_rank = max(w.shape[1] if w.numel() > 0 else 0 for w in weight_list)
output_dim = first_non_empty.shape[0]
final_shape = (len(weight_list), output_dim, max_rank)
stacked = torch.zeros(final_shape, dtype=self.dtype, device=self.device)
for i, weight in enumerate(weight_list):
if weight.numel() > 0:
if is_lora_a:
stacked[i, : weight.shape[0], :] = weight
else:
stacked[i, :, : weight.shape[1]] = weight
return stacked
def create_test_batch(
self,
batch_composition: BatchComposition,
batch_size: int,
batch_mode: BatchMode = BatchMode.PREFILL,
include_missing_k: bool = False,
) -> Tuple[
torch.Tensor,
Dict[str, Tuple[torch.Tensor, torch.Tensor]],
LoRABatchInfo,
List[int],
List[str],
]:
"""Create test batch with specified composition and mode"""
# Reset kernel cache to avoid cross-test contamination
reset_kernel_cache()
seq_lengths = self.generate_sequence_lengths(
batch_size, batch_mode, 1, self.max_seq_len
)
if batch_composition == BatchComposition.UNIFORM:
lora_assignments = ["lora_A"] * batch_size
elif batch_composition == BatchComposition.MIXED:
lora_names = ["lora_A", "lora_B", "lora_C", None]
lora_assignments = [
lora_names[i % len(lora_names)] for i in range(batch_size)
]
elif batch_composition == BatchComposition.SKEWED:
num_minority = max(1, batch_size // 8)
lora_assignments = ["lora_A"] * num_minority + ["lora_B"] * (
batch_size - num_minority
)
random.shuffle(lora_assignments)
elif batch_composition == BatchComposition.NONE:
lora_assignments = [None] * batch_size
else:
raise ValueError(f"Unknown batch composition: {batch_composition}")
total_seq_len = sum(seq_lengths)
x = torch.randn(
total_seq_len, self.input_dim, dtype=self.dtype, device=self.device
)
normalized_assignments = [
name if name is not None else "_NO_LORA_" for name in lora_assignments
]
unique_loras = set(normalized_assignments)
weights = {}
for lora_name in unique_loras:
weights[lora_name] = self.create_lora_weights(lora_name, include_missing_k)
batch_info = self.create_batch_info(
seq_lengths, normalized_assignments, batch_mode
)
return x, weights, batch_info, seq_lengths, normalized_assignments
def run_test_comparison(
self,
x: torch.Tensor,
weights: Dict[str, Tuple[torch.Tensor, torch.Tensor]],
batch_info: LoRABatchInfo,
seq_lengths: List[int],
lora_assignments: List[str],
test_name: str,
):
"""Run comparison between chunked and reference implementations"""
if not weights: # Handle case with no LoRA weights
return
# Stack LoRA A weights
lora_a_weights = [weights[name][0] for name in sorted(weights.keys())]
stacked_lora_a = self.stack_lora_weights(lora_a_weights, is_lora_a=True)
# Stack LoRA B weights
lora_b_weights = [weights[name][1] for name in sorted(weights.keys())]
stacked_lora_b = self.stack_lora_weights(lora_b_weights, is_lora_a=False)
# Test shrink operation
chunked_shrink = chunked_sgmv_lora_shrink_forward(
x, stacked_lora_a, batch_info, num_slices=3
)
reference_shrink = reference_sgmv_shrink(
x, stacked_lora_a, batch_info, seq_lengths, lora_assignments, num_slices=3
)
# Only compare valid portions of shrink output (first rank * num_slices columns per sequence)
self._compare_shrink_outputs(
chunked_shrink,
reference_shrink,
seq_lengths,
lora_assignments,
batch_info,
num_slices=3,
test_name=test_name,
)
# Test expand operation
chunked_expand = chunked_sgmv_lora_expand_forward(
reference_shrink,
stacked_lora_b,
batch_info,
self.slice_offsets,
self.max_slice_size,
base_output=None,
)
reference_expand = reference_sgmv_expand(
reference_shrink,
stacked_lora_b,
batch_info,
seq_lengths,
lora_assignments,
self.slice_offsets,
self.max_slice_size,
)
torch.testing.assert_close(
chunked_expand,
reference_expand,
rtol=self.RTOL,
atol=self.ATOL,
msg=f"Expand operation failed for {test_name}",
)
# === Basic Operations Tests ===
def test_shrink_basic(self):
"""Test basic shrink operation against PyTorch reference"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(BatchComposition.UNIFORM, batch_size)
)
lora_a_weights = [weights[name][0] for name in sorted(weights.keys())]
stacked_lora_a = self.stack_lora_weights(lora_a_weights, is_lora_a=True)
chunked_shrink = chunked_sgmv_lora_shrink_forward(
x, stacked_lora_a, batch_info, num_slices=3
)
reference_shrink = reference_sgmv_shrink(
x,
stacked_lora_a,
batch_info,
seq_lengths,
lora_assignments,
num_slices=3,
)
torch.testing.assert_close(
chunked_shrink, reference_shrink, rtol=self.RTOL, atol=self.ATOL
)
def test_expand_basic(self):
"""Test basic expand operation against PyTorch reference"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(BatchComposition.UNIFORM, batch_size)
)
lora_a_weights = [weights[name][0] for name in sorted(weights.keys())]
stacked_lora_a = self.stack_lora_weights(lora_a_weights, is_lora_a=True)
intermediate = reference_sgmv_shrink(
x,
stacked_lora_a,
batch_info,
seq_lengths,
lora_assignments,
num_slices=3,
)
lora_b_weights = [weights[name][1] for name in sorted(weights.keys())]
stacked_lora_b = self.stack_lora_weights(
lora_b_weights, is_lora_a=False
)
chunked_expand = chunked_sgmv_lora_expand_forward(
intermediate,
stacked_lora_b,
batch_info,
self.slice_offsets,
self.max_slice_size,
base_output=None,
)
reference_expand = reference_sgmv_expand(
intermediate,
stacked_lora_b,
batch_info,
seq_lengths,
lora_assignments,
self.slice_offsets,
self.max_slice_size,
)
torch.testing.assert_close(
chunked_expand, reference_expand, rtol=self.RTOL, atol=self.ATOL
)
# === QKV Operations Test ===
def test_qkv_missing_projections(self):
"""Test QKV operations with missing k_proj (Qwen3 scenario)"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(
BatchComposition.MIXED, batch_size, include_missing_k=True
)
)
self.run_test_comparison(
x,
weights,
batch_info,
seq_lengths,
lora_assignments,
f"QKV missing k_proj batch_size={batch_size}",
)
# === Batch Composition Tests ===
def test_uniform_lora_batch(self):
"""All sequences use same LoRA, random sequence lengths"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(BatchComposition.UNIFORM, batch_size)
)
self.run_test_comparison(
x,
weights,
batch_info,
seq_lengths,
lora_assignments,
f"uniform batch_size={batch_size}",
)
def test_evenly_mixed_lora_batch(self):
"""Sequences evenly distributed across LoRAs, random lengths"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(BatchComposition.MIXED, batch_size)
)
self.run_test_comparison(
x,
weights,
batch_info,
seq_lengths,
lora_assignments,
f"mixed batch_size={batch_size}",
)
def test_highly_skewed_lora_batch(self):
"""Highly uneven LoRA distribution, random lengths"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(BatchComposition.SKEWED, batch_size)
)
self.run_test_comparison(
x,
weights,
batch_info,
seq_lengths,
lora_assignments,
f"skewed batch_size={batch_size}",
)
# === Decode Mode Tests ===
def test_decode_uniform_lora_batch(self):
"""Decode mode: All sequences use same LoRA, all length 1"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(
BatchComposition.UNIFORM, batch_size, BatchMode.DECODE
)
)
self.run_test_comparison(
x,
weights,
batch_info,
seq_lengths,
lora_assignments,
f"decode uniform batch_size={batch_size}",
)
def test_decode_mixed_lora_batch(self):
"""Decode mode: Sequences distributed across LoRAs, all length 1"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(
BatchComposition.MIXED, batch_size, BatchMode.DECODE
)
)
self.run_test_comparison(
x,
weights,
batch_info,
seq_lengths,
lora_assignments,
f"decode mixed batch_size={batch_size}",
)
def test_decode_skewed_lora_batch(self):
"""Decode mode: Highly uneven LoRA distribution, all length 1"""
for batch_size in [1, 2, 16, 64]:
with self.subTest(batch_size=batch_size):
x, weights, batch_info, seq_lengths, lora_assignments = (
self.create_test_batch(
BatchComposition.SKEWED, batch_size, BatchMode.DECODE
)
)
self.run_test_comparison(
x,
weights,
batch_info,
seq_lengths,
lora_assignments,
f"decode skewed batch_size={batch_size}",
)
if __name__ == "__main__":
unittest.main()