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from vllm.model_executor.layers.fused_moe.fused_moe import fused_moe
__all__ = [
"fused_moe",
]

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"""Fused MoE kernel."""
import functools
import json
import os
from typing import Any, Dict, Optional, Tuple
import torch
import triton
import triton.language as tl
from vllm._C import ops
from vllm.logger import init_logger
from vllm.utils import is_hip
logger = init_logger(__name__)
@triton.jit
def fused_moe_kernel(
# Pointers to matrices
a_ptr,
b_ptr,
c_ptr,
topk_weights_ptr,
sorted_token_ids_ptr,
expert_ids_ptr,
num_tokens_post_padded_ptr,
# Matrix dimensions
N,
K,
EM,
num_valid_tokens,
# The stride variables represent how much to increase the ptr by when moving by 1
# element in a particular dimension. E.g. `stride_am` is how much to increase `a_ptr`
# by to get the element one row down (A has M rows).
stride_am,
stride_ak,
stride_be,
stride_bk,
stride_bn,
stride_cm,
stride_cn,
# Meta-parameters
BLOCK_SIZE_M: tl.constexpr,
BLOCK_SIZE_N: tl.constexpr,
BLOCK_SIZE_K: tl.constexpr,
GROUP_SIZE_M: tl.constexpr,
MUL_ROUTED_WEIGHT: tl.constexpr,
top_k: tl.constexpr,
compute_type: tl.constexpr,
):
"""
Implements the fused computation for a Mixture of Experts (MOE) using token and expert matrices.
Key Parameters:
- A: The input tensor representing tokens with shape (*, K), where '*' can be any shape representing batches and K is the feature dimension of each token.
- B: The stacked MOE weight tensor with shape (E, N, K), where E is the number of experts, K is the input feature dimension, and N is the output feature dimension.
- C: The output cache tensor with shape (M, topk, N), where M is the total number of tokens post padding, topk is the number of times each token is repeated,
and N is the output feature dimension.
- sorted_token_ids: A tensor containing the sorted indices of tokens, repeated topk times and arranged by the expert index they are assigned to.
- expert_ids: A tensor containing the indices of the expert for each block. It determines which expert matrix from B should be used for each block in A.
This kernel performs the multiplication of a token by its corresponding expert matrix as determined by `expert_ids`. The sorting of `sorted_token_ids`
by expert index and padding ensures divisibility by BLOCK_SIZE_M, which is necessary to maintain consistency in block matrix multiplication across different blocks processed by the same expert.
"""
# -----------------------------------------------------------
# Map program ids `pid` to the block of C it should compute.
# This is done in a grouped ordering to promote L2 data reuse.
pid = tl.program_id(axis=0)
num_pid_m = tl.cdiv(EM, BLOCK_SIZE_M)
num_pid_n = tl.cdiv(N, BLOCK_SIZE_N)
num_pid_in_group = GROUP_SIZE_M * num_pid_n
group_id = pid // num_pid_in_group
first_pid_m = group_id * GROUP_SIZE_M
group_size_m = min(num_pid_m - first_pid_m, GROUP_SIZE_M)
pid_m = first_pid_m + ((pid % num_pid_in_group) % group_size_m)
pid_n = (pid % num_pid_in_group) // group_size_m
# ----------------------------------------------------------
# Create pointers for the first blocks of A and B.
# We will advance this pointer as we move in the K direction
# and accumulate
# `a_ptrs` is a block of [BLOCK_SIZE_M, BLOCK_SIZE_K] pointers
# `b_ptrs` is a block of [BLOCK_SIZE_K, BLOCK_SIZE_N] pointers
num_tokens_post_padded = tl.load(num_tokens_post_padded_ptr)
if pid_m * BLOCK_SIZE_M >= num_tokens_post_padded:
return
offs_token_id = pid_m * BLOCK_SIZE_M + tl.arange(0, BLOCK_SIZE_M)
offs_token = tl.load(sorted_token_ids_ptr + offs_token_id)
token_mask = offs_token < num_valid_tokens
offs_bn = (pid_n * BLOCK_SIZE_N + tl.arange(0, BLOCK_SIZE_N)) % N
offs_k = tl.arange(0, BLOCK_SIZE_K)
a_ptrs = a_ptr + (offs_token[:, None] // top_k * stride_am +
offs_k[None, :] * stride_ak)
off_experts = tl.load(expert_ids_ptr + pid_m)
b_ptrs = b_ptr + off_experts * stride_be + (offs_k[:, None] * stride_bk +
offs_bn[None, :] * stride_bn)
# -----------------------------------------------------------
# Iterate to compute a block of the C matrix.
# We accumulate into a `[BLOCK_SIZE_M, BLOCK_SIZE_N]` block
# of fp32 values for higher accuracy.
# `accumulator` will be converted back to fp16 after the loop.
accumulator = tl.zeros((BLOCK_SIZE_M, BLOCK_SIZE_N), dtype=tl.float32)
for k in range(0, tl.cdiv(K, BLOCK_SIZE_K)):
# Load the next block of A and B, generate a mask by checking the K dimension.
a = tl.load(a_ptrs,
mask=token_mask[:, None] &
(offs_k[None, :] < K - k * BLOCK_SIZE_K),
other=0.0)
b = tl.load(b_ptrs,
mask=offs_k[:, None] < K - k * BLOCK_SIZE_K,
other=0.0)
# We accumulate along the K dimension.
accumulator += tl.dot(a, b)
# Advance the ptrs to the next K block.
a_ptrs += BLOCK_SIZE_K * stride_ak
b_ptrs += BLOCK_SIZE_K * stride_bk
if MUL_ROUTED_WEIGHT:
moe_weight = tl.load(topk_weights_ptr + offs_token,
mask=token_mask,
other=0)
accumulator = accumulator * moe_weight[:, None]
accumulator = accumulator.to(compute_type)
# -----------------------------------------------------------
# Write back the block of the output
offs_cn = pid_n * BLOCK_SIZE_N + tl.arange(0, BLOCK_SIZE_N)
c_ptrs = c_ptr + stride_cm * offs_token[:, None] + stride_cn * offs_cn[
None, :]
c_mask = token_mask[:, None] & (offs_cn[None, :] < N)
tl.store(c_ptrs, accumulator, mask=c_mask)
def moe_align_block_size(
topk_ids: torch.Tensor, block_size: int,
num_experts: int) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
"""
Aligns the token distribution across experts to be compatible with block size for matrix multiplication.
Parameters:
- topk_ids: A tensor of shape [total_tokens, top_k] representing the top-k expert indices for each token.
- block_size: The block size used in block matrix multiplication.
- num_experts: The total number of experts.
Returns:
- sorted_token_ids: A tensor containing the sorted token indices according to their allocated expert.
- expert_ids: A tensor indicating the assigned expert index for each block.
- num_tokens_post_padded: The total number of tokens after padding, ensuring divisibility by block_size.
This function pads the number of tokens that each expert needs to process so that it is divisible by block_size.
Padding ensures that during block matrix multiplication, the dimensions align correctly.
Example:
Given topk_ids = [[2, 3, 4], [1, 2, 4], [1, 3, 4], [1, 2, 3]], block_size = 4, and num_experts = 4:
- We initially have 12 tokens (after repeating 'top_k' times) and 4 experts, with each expert needing to process 3 tokens.
- As block_size is 4, we pad 1 token for each expert.
- First, flatten topk_ids to [2, 3, 4, 1, 2, 4, 1, 3, 4, 1, 2, 3].
- Then append padding tokens [12, 12, 12, 12] for each block.
- After sorting by expert index, we obtain token_ids [3, 6, 9, 12, 0, 4, 10, 12, 1, 7, 11, 12, 2, 5, 8, 12].
Tokens 12 are non-existent (padding) and are ignored in the subsequent matrix multiplication.
- The padding ensures that the total number of tokens is now divisible by block_size for proper block matrix operations.
"""
sorted_ids = torch.empty(
(topk_ids.numel() + num_experts * (block_size - 1), ),
dtype=torch.int32,
device=topk_ids.device)
expert_ids = torch.empty((topk_ids.numel() + num_experts, ),
dtype=torch.int32,
device=topk_ids.device)
sorted_ids.fill_(topk_ids.numel())
num_tokens_post_pad = torch.empty((1),
dtype=torch.int32,
device=topk_ids.device)
ops.moe_align_block_size(topk_ids, num_experts, block_size, sorted_ids,
expert_ids, num_tokens_post_pad)
return sorted_ids, expert_ids, num_tokens_post_pad
def invoke_fused_moe_kernel(A: torch.Tensor, B: torch.Tensor, C: torch.Tensor,
topk_weights: torch.Tensor, topk_ids: torch.Tensor,
sorted_token_ids: torch.Tensor,
expert_ids: torch.Tensor,
num_tokens_post_padded: torch.Tensor,
mul_routed_weight: bool, top_k: int,
config: Dict[str, Any]) -> None:
assert topk_weights.stride(1) == 1
assert sorted_token_ids.stride(0) == 1
grid = lambda META: (triton.cdiv(sorted_token_ids.shape[0], META[
'BLOCK_SIZE_M']) * triton.cdiv(B.shape[1], META['BLOCK_SIZE_N']), )
fused_moe_kernel[grid](
A,
B,
C,
topk_weights,
sorted_token_ids,
expert_ids,
num_tokens_post_padded,
B.shape[1],
B.shape[2],
sorted_token_ids.shape[0],
topk_ids.numel(),
A.stride(0),
A.stride(1),
B.stride(0),
B.stride(2),
B.stride(1),
C.stride(1),
C.stride(2),
MUL_ROUTED_WEIGHT=mul_routed_weight,
top_k=top_k,
compute_type=tl.bfloat16 if A.dtype == torch.bfloat16 else tl.float16,
**config,
)
@functools.lru_cache
def get_moe_configs(E: int, N: int) -> Optional[Dict[int, Any]]:
"""
Return optimized configurations for the fused MoE kernel.
The return value will be a dictionary that maps an irregular grid of batch sizes
to configurations of the fused_moe kernel. To evaluate the kernel on a given batch
size bs, the closest batch size in the grid should be picked and the associated
configuration chosen to invoke the kernel.
"""
# First look up if an optimized configuration is available in the configs directory
device_name = torch.cuda.get_device_name().replace(" ", "_")
config_file_path = os.path.join(
os.path.dirname(os.path.realpath(__file__)), "configs",
f"E={E},N={N},device_name={device_name}.json")
if os.path.exists(config_file_path):
with open(config_file_path) as f:
logger.info(
f"Using configuration from {config_file_path} for MoE layer.")
# If a configuration has been found, return it
return {int(key): val for key, val in json.load(f).items()}
# If no optimized configuration is available, we will use the default configuration
return None
def fused_moe(
hidden_states: torch.Tensor,
w1: torch.Tensor,
w2: torch.Tensor,
gating_output: torch.Tensor,
topk: int,
renormalize: bool,
inplace: bool = False,
override_config: Optional[Dict[str, Any]] = None,
) -> torch.Tensor:
"""
This function computes a Mixture of Experts (MoE) layer using two sets of weights, w1 and w2, and top-k gating mechanism.
Parameters:
- hidden_states (torch.Tensor): The input tensor to the MoE layer.
- w1 (torch.Tensor): The first set of expert weights.
- w2 (torch.Tensor): The second set of expert weights.
- gating_output (torch.Tensor): The output of the gating operation (before softmax).
- topk (int): The number of top-k experts to select.
- renormalize (bool): If True, renormalize the top-k weights to sum to 1.
- inplace (bool): If True, perform the operation in-place. Defaults to False.
- override_config (Optional[Dict[str, Any]]): Optional override for the kernel configuration.
Returns:
- torch.Tensor: The output tensor after applying the MoE layer.
"""
# Check constraints.
assert hidden_states.shape[0] == gating_output.shape[0], (
"Number of tokens mismatch")
assert hidden_states.shape[1] == w1.shape[2], "Hidden size mismatch"
assert gating_output.shape[1] == w1.shape[0], "Number of experts mismatch"
assert hidden_states.is_contiguous(), "Hidden_states must be contiguous"
assert w1.is_contiguous(), "Expert weights1 must be contiguous"
assert w2.is_contiguous(), "Expert weights2 must be contiguous"
assert hidden_states.dtype in [
torch.float32, torch.float16, torch.bfloat16
]
M, _ = hidden_states.shape
E, N, _ = w1.shape
if is_hip():
# The MoE kernels are not yet supported on ROCm.
routing_weights = torch.softmax(gating_output,
dim=-1,
dtype=torch.float32)
topk_weights, topk_ids = torch.topk(routing_weights, topk, dim=-1)
else:
import vllm._moe_C as moe_kernels
topk_weights = torch.empty(M,
topk,
dtype=torch.float32,
device=hidden_states.device)
topk_ids = torch.empty(M,
topk,
dtype=torch.int32,
device=hidden_states.device)
token_expert_indicies = torch.empty(M,
topk,
dtype=torch.int32,
device=hidden_states.device)
moe_kernels.topk_softmax(
topk_weights,
topk_ids,
token_expert_indicies,
gating_output.float(), # TODO(woosuk): Optimize this.
)
del token_expert_indicies # Not used. Will be used in the future.
if renormalize:
topk_weights = topk_weights / topk_weights.sum(dim=-1, keepdim=True)
if override_config:
config = override_config
else:
# First try to load optimal config from the file
configs = get_moe_configs(E, w2.shape[2])
if configs:
# If an optimal configuration map has been found, look up the optimal config
config = configs[min(configs.keys(), key=lambda x: abs(x - M))]
else:
# Else use the default config
config = {
'BLOCK_SIZE_M': 64,
'BLOCK_SIZE_N': 64,
'BLOCK_SIZE_K': 32,
'GROUP_SIZE_M': 8
}
if M <= E:
config = {
'BLOCK_SIZE_M': 16,
'BLOCK_SIZE_N': 32,
'BLOCK_SIZE_K': 64,
'GROUP_SIZE_M': 1
}
intermediate_cache1 = torch.empty((M, topk_ids.shape[1], N),
device=hidden_states.device,
dtype=hidden_states.dtype)
intermediate_cache2 = torch.empty((M * topk_ids.shape[1], N // 2),
device=hidden_states.device,
dtype=hidden_states.dtype)
intermediate_cache3 = torch.empty((M, topk_ids.shape[1], w2.shape[1]),
device=hidden_states.device,
dtype=hidden_states.dtype)
sorted_token_ids, expert_ids, num_tokens_post_padded = moe_align_block_size(
topk_ids, config['BLOCK_SIZE_M'], E)
invoke_fused_moe_kernel(hidden_states, w1, intermediate_cache1,
topk_weights, topk_ids, sorted_token_ids,
expert_ids, num_tokens_post_padded, False,
topk_ids.shape[1], config)
ops.silu_and_mul(intermediate_cache2, intermediate_cache1.view(-1, N))
invoke_fused_moe_kernel(intermediate_cache2, w2, intermediate_cache3,
topk_weights, topk_ids, sorted_token_ids,
expert_ids, num_tokens_post_padded, True, 1,
config)
if inplace:
return torch.sum(intermediate_cache3.view(*intermediate_cache3.shape),
dim=1,
out=hidden_states)
return torch.sum(intermediate_cache3.view(*intermediate_cache3.shape),
dim=1)