Files
sglang/python/sglang/srt/disaggregation/nixl/conn.py
2025-09-09 16:47:26 +08:00

697 lines
26 KiB
Python

from __future__ import annotations
import asyncio
import dataclasses
import logging
import queue
import socket
import struct
import threading
import uuid
from collections import defaultdict
from functools import cache
from typing import Dict, List, Optional, Set, Tuple, TypeAlias, Union
import numpy as np
import numpy.typing as npt
import requests
import zmq
from aiohttp import web
from sglang.srt.disaggregation.base.conn import BaseKVSender, KVArgs, KVPoll
from sglang.srt.disaggregation.common.conn import (
CommonKVBootstrapServer,
CommonKVManager,
CommonKVReceiver,
)
from sglang.srt.disaggregation.common.utils import group_concurrent_contiguous
from sglang.srt.disaggregation.utils import DisaggregationMode
from sglang.srt.server_args import ServerArgs
from sglang.srt.utils import (
format_tcp_address,
get_local_ip_auto,
is_valid_ipv6_address,
)
logger = logging.getLogger(__name__)
GUARD = "NixlMsgGuard".encode("ascii")
@dataclasses.dataclass
class TransferInfo:
"""Contains indices for a transfer, sent by KVReceiver. Received by prefill bootstrap thread."""
room: int
endpoint: str
dst_port: int
agent_name: str
dst_kv_indices: npt.NDArray[np.int32]
dst_aux_index: int
required_dst_info_num: int
def is_dummy(self):
return self.dst_kv_indices.size == 0
@classmethod
def from_zmq(cls, msg: List[bytes]):
return cls(
room=int(msg[0].decode("ascii")),
endpoint=msg[1].decode("ascii"),
dst_port=int(msg[2].decode("ascii")),
agent_name=msg[3].decode("ascii"),
dst_kv_indices=np.frombuffer(msg[4], dtype=np.int32),
dst_aux_index=int(msg[5].decode("ascii")),
required_dst_info_num=int(msg[6].decode("ascii")),
)
@dataclasses.dataclass
class KVArgsRegisterInfo:
"""Contains base pointers and other info which only needs to be sent once by KVReceiver. Received by prefill bootstrap thread."""
room: str
endpoint: str
dst_port: int
agent_name: str
agent_metadata: bytes
dst_kv_ptrs: list[int]
dst_aux_ptrs: list[int]
gpu_id: int
decode_tp_size: int
decode_tp_rank: int
dst_kv_item_len: int
@classmethod
def from_zmq(cls, msg: List[bytes]):
return cls(
room=str(msg[0].decode("ascii")),
endpoint=msg[1].decode("ascii"),
dst_port=int(msg[2].decode("ascii")),
agent_name=msg[3].decode("ascii"),
agent_metadata=msg[4],
dst_kv_ptrs=list(struct.unpack(f"{len(msg[5])//8}Q", msg[5])),
dst_aux_ptrs=list(struct.unpack(f"{len(msg[6])//8}Q", msg[6])),
gpu_id=int(msg[7].decode("ascii")),
decode_tp_size=int(msg[8].decode("ascii")),
decode_tp_rank=int(msg[9].decode("ascii")),
dst_kv_item_len=int(msg[10].decode("ascii")),
)
@dataclasses.dataclass
class TransferStatus:
"""Used by KV Receiver to know when a transfer is done."""
# KV chunk IDs that have been received.
received_kvs: Set[int] = dataclasses.field(default_factory=set)
# Number of kv chunks to expect, will know this after last chunk is received.
num_kvs_expected: Optional[int] = None
# Whether aux data has been received.
received_aux: bool = False
def is_done(self):
if self.num_kvs_expected is None:
return False
return self.num_kvs_expected == len(self.received_kvs) and self.received_aux
class NixlKVManager(CommonKVManager):
def __init__(
self,
args: KVArgs,
disaggregation_mode: DisaggregationMode,
server_args: ServerArgs,
is_mla_backend: Optional[bool] = False,
):
super().__init__(args, disaggregation_mode, server_args, is_mla_backend)
try:
from nixl._api import nixl_agent
except ImportError as e:
raise ImportError(
"Please install NIXL by following the instructions at "
"https://github.com/ai-dynamo/nixl/blob/main/README.md "
"to run SGLang with NixlTransferEngine."
) from e
self.agent = nixl_agent(str(uuid.uuid4()))
self.local_ip = get_local_ip_auto()
self.server_socket = zmq.Context().socket(zmq.PULL)
if is_valid_ipv6_address(self.local_ip):
self.server_socket.setsockopt(zmq.IPV6, 1)
self.register_buffer_to_engine()
if self.disaggregation_mode == DisaggregationMode.PREFILL:
self.request_status: Dict[int, KVPoll] = {}
self.transfer_infos: Dict[int, Dict[str, TransferInfo]] = {}
self.decode_kv_args_table: Dict[str, KVArgsRegisterInfo] = {}
self._start_bootstrap_thread()
elif self.disaggregation_mode == DisaggregationMode.DECODE:
self.transfer_statuses: Dict[int, TransferStatus] = defaultdict(
TransferStatus
)
else:
raise ValueError(
f"Unsupported DisaggregationMode: {self.disaggregation_mode}"
)
def check_status(self, bootstrap_room: int):
return self.request_status[bootstrap_room]
def update_status(self, bootstrap_room: int, status: KVPoll):
if bootstrap_room not in self.request_status:
self.request_status[bootstrap_room] = status
else:
# NOTE: The prefill engine could recv bootstrapping first
self.request_status[bootstrap_room] = max(
self.request_status[bootstrap_room], status
)
def register_buffer_to_engine(self):
kv_addrs = []
for kv_data_ptr, kv_data_len in zip(
self.kv_args.kv_data_ptrs, self.kv_args.kv_data_lens
):
kv_addrs.append((kv_data_ptr, kv_data_len, self.kv_args.gpu_id, ""))
self.kv_descs = self.agent.register_memory(kv_addrs, "VRAM")
logger.debug(f"Register kv tensors, len(kv_addr)= {len(kv_addrs)}")
if not self.kv_descs:
raise Exception("NIXL memory registration failed for kv tensors")
aux_addrs = []
for aux_data_ptr, aux_data_len in zip(
self.kv_args.aux_data_ptrs, self.kv_args.aux_data_lens
):
aux_addrs.append((aux_data_ptr, aux_data_len, 0, ""))
self.aux_descs = self.agent.register_memory(aux_addrs, "DRAM")
logger.debug(f"Register aux tensors, len(aux_addrs)= {len(aux_addrs)}")
if not self.aux_descs:
raise Exception("NIXL memory registration failed for aux tensors")
def _add_remote_peer(self, decode_kv_args: KVArgsRegisterInfo):
agent_name = decode_kv_args.agent_name
if agent_name in self.decode_kv_args_table:
logger.info(f"Peer {agent_name} was already registered, ignoring.")
return
self.decode_kv_args_table[agent_name] = decode_kv_args
self.agent.add_remote_agent(decode_kv_args.agent_metadata)
def send_kvcache(
self,
peer_name: str,
prefill_kv_indices: npt.NDArray[np.int32],
dst_kv_ptrs: list[int],
dst_kv_indices: npt.NDArray[np.int32],
dst_gpu_id: int,
notif: str,
):
# group by indices
prefill_kv_blocks, dst_kv_blocks = group_concurrent_contiguous(
prefill_kv_indices, dst_kv_indices
)
logger.debug(f"sending kvcache to {peer_name} with notif {notif}")
# Make descs
num_layers = len(self.kv_args.kv_data_ptrs)
src_addrs = []
dst_addrs = []
for layer_id in range(num_layers):
src_ptr = self.kv_args.kv_data_ptrs[layer_id]
dst_ptr = dst_kv_ptrs[layer_id]
item_len = self.kv_args.kv_item_lens[layer_id]
for prefill_index, decode_index in zip(prefill_kv_blocks, dst_kv_blocks):
src_addr = src_ptr + int(prefill_index[0]) * item_len
dst_addr = dst_ptr + int(decode_index[0]) * item_len
length = item_len * len(prefill_index)
src_addrs.append((src_addr, length, self.kv_args.gpu_id))
dst_addrs.append((dst_addr, length, dst_gpu_id))
logger.debug(
f"len(src_addrs): before group: {len(prefill_kv_indices)}, after group: {len(src_addrs)}"
)
src_descs = self.agent.get_xfer_descs(src_addrs, "VRAM")
dst_descs = self.agent.get_xfer_descs(dst_addrs, "VRAM")
# Transfer data
xfer_handle = self.agent.initialize_xfer(
"WRITE",
src_descs,
dst_descs,
peer_name,
notif.encode("ascii"), # type: ignore
)
if not xfer_handle:
raise Exception("KVSender failed to create transfer")
state = self.agent.transfer(xfer_handle)
if state == "ERR":
raise Exception("KVSender failed to post transfer")
return xfer_handle
def send_kvcache_slice(
self,
peer_name: str,
prefill_kv_indices: npt.NDArray[np.int32],
dst_kv_ptrs: list[int],
dst_kv_indices: npt.NDArray[np.int32],
dst_gpu_id: int,
notif: str,
prefill_tp_size: int,
decode_tp_size: int,
decode_tp_rank: int,
dst_kv_item_len: int,
):
# Get configuration from kv_args
local_tp_rank_in_group = self.kv_args.engine_rank % prefill_tp_size
dst_tp_rank_in_group = decode_tp_rank % decode_tp_size
num_kv_heads = self.kv_args.kv_head_num
# Calculate head distribution
src_heads_per_rank = num_kv_heads
dst_heads_per_rank = num_kv_heads * prefill_tp_size // decode_tp_size
src_kv_item_len = self.kv_args.kv_item_lens[0]
page_size = self.kv_args.page_size
bytes_per_head_slice_to_send = (
dst_kv_item_len // page_size // dst_heads_per_rank
)
# Determine which heads to send
if prefill_tp_size > decode_tp_size:
# Multiple prefill ranks to one decode rank
src_head_start_offset = 0
num_heads_to_send = src_heads_per_rank
dst_head_start_offset = local_tp_rank_in_group * src_heads_per_rank
else:
# Send KVCache from 1 prefill instance to multiple decode instances
src_head_start_offset = (
dst_tp_rank_in_group * dst_heads_per_rank
) % src_heads_per_rank
num_heads_to_send = dst_heads_per_rank
dst_head_start_offset = 0
# Create transfer descriptors
src_addrs = []
dst_addrs = []
bytes_per_token_on_prefill = src_kv_item_len // page_size
bytes_per_token_on_decode = dst_kv_item_len // page_size
num_kv_layers = len(self.kv_args.kv_data_ptrs) // 2
src_k_ptrs = self.kv_args.kv_data_ptrs[:num_kv_layers]
src_v_ptrs = self.kv_args.kv_data_ptrs[num_kv_layers:]
dst_k_ptrs = dst_kv_ptrs[0 : len(src_k_ptrs)]
dst_v_ptrs = dst_kv_ptrs[num_kv_layers : num_kv_layers + len(src_v_ptrs)]
# Calculate precise byte offset and length for the sub-slice within the token
src_head_slice_offset = src_head_start_offset * bytes_per_head_slice_to_send
dst_head_slice_offset = dst_head_start_offset * bytes_per_head_slice_to_send
heads_bytes_per_token_to_send = num_heads_to_send * bytes_per_head_slice_to_send
src_dst_ptr_pairs = [
(
src_k_ptrs[layer_id],
dst_k_ptrs[layer_id],
)
for layer_id in range(len(src_k_ptrs))
] + [
(
src_v_ptrs[layer_id],
dst_v_ptrs[layer_id],
)
for layer_id in range(len(src_v_ptrs))
]
src_addrs = []
dst_addrs = []
# Calculate strides for a single token slot
bytes_per_token_on_prefill = src_kv_item_len // page_size
bytes_per_token_on_decode = dst_kv_item_len // page_size
for src_ptr, dst_ptr in src_dst_ptr_pairs:
for i in range(len(prefill_kv_indices)):
prefill_page_idx = int(prefill_kv_indices[i])
decode_page_idx = int(dst_kv_indices[i])
# Get the starting addresses for the current src and dst pages
src_page_start_addr = src_ptr + prefill_page_idx * src_kv_item_len
dst_page_start_addr = dst_ptr + decode_page_idx * dst_kv_item_len
# Iterate through each valid token slot within the current page
for token_slot_in_page in range(page_size):
# Calculate the start address of the current token slot
src_token_slot_start_addr = (
src_page_start_addr
+ token_slot_in_page * bytes_per_token_on_prefill
)
dst_token_slot_start_addr = (
dst_page_start_addr
+ token_slot_in_page * bytes_per_token_on_decode
)
# Calculate final src and dst addresses by applying head-slice offsets
src_slice_addr = src_token_slot_start_addr + src_head_slice_offset
dst_slice_addr = dst_token_slot_start_addr + dst_head_slice_offset
src_addrs.append(
(
src_slice_addr,
heads_bytes_per_token_to_send,
self.kv_args.gpu_id,
)
)
dst_addrs.append(
(dst_slice_addr, heads_bytes_per_token_to_send, dst_gpu_id)
)
# Use NIXL agent for transfer
src_descs = self.agent.get_xfer_descs(src_addrs, "VRAM")
dst_descs = self.agent.get_xfer_descs(dst_addrs, "VRAM")
xfer_handle = self.agent.initialize_xfer(
"WRITE", src_descs, dst_descs, peer_name, notif.encode("ascii")
)
if not xfer_handle:
raise Exception("Failed to create sliced KV transfer")
state = self.agent.transfer(xfer_handle)
if state == "ERR":
raise Exception("Failed to post sliced KV transfer")
return xfer_handle
def send_aux(
self,
peer_name: str,
prefill_aux_index: int,
dst_aux_ptrs: list[int],
dst_aux_index: int,
notif: str,
):
# Make descs
aux_item_len = self.kv_args.aux_item_lens[0]
prefill_aux_addr = (
self.kv_args.aux_data_ptrs[0] + prefill_aux_index * aux_item_len
)
decode_aux_addr = dst_aux_ptrs[0] + dst_aux_index * aux_item_len
src_addrs = [(prefill_aux_addr, aux_item_len, 0)]
dst_addrs = [(decode_aux_addr, aux_item_len, 0)]
src_descs = self.agent.get_xfer_descs(src_addrs, "DRAM")
dst_descs = self.agent.get_xfer_descs(dst_addrs, "DRAM")
# Transfer data
xfer_handle = self.agent.initialize_xfer(
"WRITE",
src_descs,
dst_descs,
peer_name,
notif.encode("ascii"), # type: ignore
)
if not xfer_handle:
raise Exception("KVSender failed to create transfer")
state = self.agent.transfer(xfer_handle)
if state == "ERR":
raise Exception("KVSender failed to post transfer")
return xfer_handle
def add_transfer_request(
self,
bootstrap_room: int,
kv_indices: npt.NDArray[np.int32],
index_slice: slice,
is_last: bool,
chunk_id: int,
aux_index: Optional[int] = None,
):
assert self.disaggregation_mode == DisaggregationMode.PREFILL
assert not is_last or (is_last and aux_index is not None)
reqs_to_be_processed = self.transfer_infos[bootstrap_room].values()
handles = []
for req in reqs_to_be_processed:
assert bootstrap_room == req.room
if req.is_dummy():
continue
chunked_dst_kv_indice = req.dst_kv_indices[index_slice]
assert len(chunked_dst_kv_indice) == len(kv_indices)
assert req.agent_name in self.decode_kv_args_table
notif = "_".join([str(req.room), "kv", str(chunk_id), str(int(is_last))])
decode_tp_size = self.decode_kv_args_table[req.agent_name].decode_tp_size
if decode_tp_size == self.tp_size:
kv_xfer_handle = self.send_kvcache(
req.agent_name,
kv_indices,
self.decode_kv_args_table[req.agent_name].dst_kv_ptrs,
chunked_dst_kv_indice,
self.decode_kv_args_table[req.agent_name].gpu_id,
notif,
)
else:
kv_xfer_handle = self.send_kvcache_slice(
req.agent_name,
kv_indices,
self.decode_kv_args_table[req.agent_name].dst_kv_ptrs,
chunked_dst_kv_indice,
self.decode_kv_args_table[req.agent_name].gpu_id,
notif,
prefill_tp_size=self.tp_size,
decode_tp_size=decode_tp_size,
decode_tp_rank=self.decode_kv_args_table[
req.agent_name
].decode_tp_rank,
dst_kv_item_len=self.decode_kv_args_table[
req.agent_name
].dst_kv_item_len,
)
handles.append(kv_xfer_handle)
# Only the last chunk we need to send the aux data.
if is_last:
assert aux_index is not None
aux_xfer_handle = self.send_aux(
req.agent_name,
aux_index,
self.decode_kv_args_table[req.agent_name].dst_aux_ptrs,
req.dst_aux_index,
str(req.room) + "_aux",
)
handles.append(aux_xfer_handle)
if is_last:
del self.transfer_infos[bootstrap_room]
return handles
def update_transfer_status(self):
# Process notifications from received transfers.
notif_map = self.agent.get_new_notifs()
for peer_name, messages in notif_map.items():
# We could also check that self.bootstrap_info['agent_name'] matches
# the message sender. But the bootstrap room alone should be
# sufficient to map the status.
for msg in messages:
components = msg.decode("ascii").split("_")
room = int(components[0])
if components[1] == "kv":
chunk_id = int(components[2])
is_last = bool(int(components[3]))
self.transfer_statuses[room].received_kvs.add(chunk_id)
if is_last:
self.transfer_statuses[room].num_kvs_expected = chunk_id + 1
elif components[1] == "aux":
self.transfer_statuses[room].received_aux = True
def check_transfer_done(self, room: int):
if room not in self.transfer_statuses:
return False
return self.transfer_statuses[room].is_done()
def _bind_server_socket(self):
self.server_socket.bind(format_tcp_address(self.local_ip, self.rank_port))
def _start_bootstrap_thread(self):
self._bind_server_socket()
def bootstrap_thread():
"""This thread recvs transfer info from the decode engine"""
while True:
waiting_req_bytes = self.server_socket.recv_multipart()
logger.debug(
f"Received multipart with total byte size {sum(len(x) for x in waiting_req_bytes)}"
)
assert (
waiting_req_bytes[0] == GUARD
), f"First message should be {GUARD}. Foreign traffic?"
waiting_req_bytes = waiting_req_bytes[1:]
room = waiting_req_bytes[0].decode("ascii")
agent_name = waiting_req_bytes[3].decode("ascii")
if room == "None":
# Register new peer and save KV base pointers.
self._add_remote_peer(
KVArgsRegisterInfo.from_zmq(waiting_req_bytes)
)
logger.debug(f"Register KVArgs from {agent_name} successfully")
continue
room = int(room)
if room not in self.transfer_infos:
self.transfer_infos[room] = {}
self.transfer_infos[room][agent_name] = TransferInfo.from_zmq(
waiting_req_bytes
)
required_dst_info_num = self.transfer_infos[room][
agent_name
].required_dst_info_num
logger.debug(f"got info {room=} {agent_name=} {required_dst_info_num=}")
if len(self.transfer_infos[room]) == required_dst_info_num:
logger.debug(f"{room=} is bootstrapped")
self.update_status(room, KVPoll.WaitingForInput)
threading.Thread(target=bootstrap_thread).start()
class NixlKVSender(BaseKVSender):
def __init__(
self,
mgr: NixlKVManager,
bootstrap_addr: str,
bootstrap_room: int,
dest_tp_ranks: List[int],
pp_rank: int,
):
self.kv_mgr = mgr
self.bootstrap_room = bootstrap_room
self.aux_index = None
self.bootstrap_server_url = bootstrap_addr
self.xfer_handles = []
self.has_sent = False
self.chunk_id = 0
self.kv_mgr.update_status(self.bootstrap_room, KVPoll.Bootstrapping)
# inner state
self.curr_idx = 0
def init(self, num_kv_indices: int, aux_index: Optional[int] = None):
self.num_kv_indices = num_kv_indices
self.aux_index = aux_index
def send(
self,
kv_indices: npt.NDArray[np.int32],
):
index_slice = slice(self.curr_idx, self.curr_idx + len(kv_indices))
self.curr_idx += len(kv_indices)
is_last = self.curr_idx == self.num_kv_indices
new_xfer_handles = self.kv_mgr.add_transfer_request(
self.bootstrap_room,
kv_indices,
index_slice,
is_last,
self.chunk_id,
self.aux_index,
)
self.xfer_handles.extend(new_xfer_handles)
self.chunk_id += 1
if is_last:
self.has_sent = True
del self.kv_mgr.request_status[self.bootstrap_room]
def poll(self) -> KVPoll:
if not self.has_sent:
return self.kv_mgr.check_status(self.bootstrap_room)
states = [self.kv_mgr.agent.check_xfer_state(x) for x in self.xfer_handles]
if all([x == "DONE" for x in states]):
return KVPoll.Success # type: ignore
if any([x == "ERR" for x in states]):
raise Exception("KVSender transfer encountered an error.")
return KVPoll.WaitingForInput # type: ignore
def failure_exception(self):
raise Exception("Fake KVSender Exception")
class NixlKVReceiver(CommonKVReceiver):
def __init__(
self,
mgr: NixlKVManager,
bootstrap_addr: str,
bootstrap_room: Optional[int] = None,
prefill_dp_rank: Optional[int] = None,
):
self.started_transfer = False
self.conclude_state = None
super().__init__(mgr, bootstrap_addr, bootstrap_room, prefill_dp_rank)
def init(self, kv_indices: npt.NDArray[np.int32], aux_index: Optional[int] = None):
for bootstrap_info in self.bootstrap_infos:
logger.debug(
f"Fetched bootstrap info: {bootstrap_info} for engine rank: {self.kv_mgr.kv_args.engine_rank}"
)
sock, lock = self._connect_to_bootstrap_server(bootstrap_info)
is_dummy = bootstrap_info["is_dummy"]
logger.debug(
f"Sending to prefill server with bootstrap room {self.bootstrap_room} {is_dummy=}"
)
with lock:
sock.send_multipart(
[
GUARD,
str(self.bootstrap_room).encode("ascii"),
self.kv_mgr.local_ip.encode("ascii"),
str(self.kv_mgr.rank_port).encode("ascii"),
self.kv_mgr.agent.name.encode("ascii"),
kv_indices.tobytes() if not is_dummy else b"",
str(aux_index).encode("ascii"),
str(self.required_dst_info_num).encode("ascii"),
]
)
self.started_transfer = True
def poll(self) -> KVPoll:
if self.conclude_state is not None:
return self.conclude_state
if not self.started_transfer:
return KVPoll.WaitingForInput # type: ignore
self.kv_mgr.update_transfer_status()
if self.kv_mgr.check_transfer_done(self.bootstrap_room): # type: ignore
self.conclude_state = KVPoll.Success
del self.kv_mgr.transfer_statuses[self.bootstrap_room]
return KVPoll.Success # type: ignore
return KVPoll.WaitingForInput # type: ignore
def _register_kv_args(self):
for bootstrap_info in self.bootstrap_infos:
sock, lock = self._connect_to_bootstrap_server(bootstrap_info)
packed_kv_data_ptrs = b"".join(
struct.pack("Q", ptr) for ptr in self.kv_mgr.kv_args.kv_data_ptrs
)
packed_aux_data_ptrs = b"".join(
struct.pack("Q", ptr) for ptr in self.kv_mgr.kv_args.aux_data_ptrs
)
with lock:
sock.send_multipart(
[
GUARD,
"None".encode("ascii"),
self.kv_mgr.local_ip.encode("ascii"),
str(self.kv_mgr.rank_port).encode("ascii"),
self.kv_mgr.agent.name.encode("ascii"),
self.kv_mgr.agent.get_agent_metadata(),
packed_kv_data_ptrs,
packed_aux_data_ptrs,
str(self.kv_mgr.kv_args.gpu_id).encode("ascii"),
str(self.kv_mgr.kv_args.decode_tp_size).encode("ascii"),
str(self.kv_mgr.kv_args.engine_rank).encode("ascii"),
str(self.kv_mgr.kv_args.kv_item_lens[0]).encode("ascii"),
]
)
def failure_exception(self):
raise Exception("Fake KVReceiver Exception")
class NixlKVBootstrapServer(CommonKVBootstrapServer):
pass