Add 2 Node AllReduce DSL Algorithm (#636)

This PR creates two allreduce algorithms designed for a 2-node
environment. These algorithms are in-place and non-zero copy.
This commit is contained in:
Caio Rocha
2025-10-01 17:00:17 -07:00
committed by GitHub
parent 79e9e613a8
commit b76f3ebf39

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@@ -0,0 +1,199 @@
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.
"""
Multi-node AllReduce implementation using packet-based communication.
This implements a hierarchical AllReduce: intra-node allreduce followed by
inter-node exchange and final intra-node allreduce.
"""
import argparse
from mscclpp.language.channel import *
from mscclpp.language.rank import *
from mscclpp.language.general import *
from mscclpp.language.program import *
from mscclpp.language.collectives import *
def allreduce_example(
program_name, gpus_per_node, thread_block_group_size, num_threads_per_block, min_message_size, max_message_size
):
"""
Implements a multi-node AllReduce using a hierarchical approach:
1. Intra-node allreduce
2. Inter-node exchange (exchange reduced data between nodes)
3. Intra-node allreduce
"""
# Configuration constants
num_nodes = 2
total_gpus = num_nodes * gpus_per_node
chunks_per_loop = 1
packets_per_gpu = 2 # Each GPU handles 2 data packets
# Initialize collective operation
collective = AllReduce(total_gpus, chunks_per_loop, True)
with CollectiveProgram(
program_name,
collective,
total_gpus,
protocol="LL",
num_threads_per_block=num_threads_per_block,
reuse_resources=False,
use_double_scratch_buffer=True,
min_message_size=min_message_size,
max_message_size=max_message_size,
):
# Initialize communication channels and buffers
intra_node_memory_channels = {}
inter_node_port_channels = {}
scratch_buffers = []
thread_block_offset = 1
thread_block_group = ThreadBlockGroup(
tb_list=[i for i in range(thread_block_offset, thread_block_offset + thread_block_group_size)]
)
for node_id in range(num_nodes):
for local_gpu_id in range(gpus_per_node):
current_rank_id = local_gpu_id + gpus_per_node * node_id
next_node_rank_id = (local_gpu_id + gpus_per_node * (node_id + 1)) % total_gpus
scratch_buffer_size = 2 * total_gpus
scratch_buffers.append(Buffer(current_rank_id, scratch_buffer_size))
for peer_gpu_id in range(gpus_per_node):
if peer_gpu_id != local_gpu_id:
peer_rank_id = peer_gpu_id + gpus_per_node * node_id
intra_node_memory_channels[(peer_rank_id, current_rank_id)] = MemoryChannel(
peer_rank_id, current_rank_id
)
inter_node_port_channels[current_rank_id] = PortChannel(next_node_rank_id, current_rank_id)
# AllReduce
for node_id in range(num_nodes):
for local_gpu_id in range(gpus_per_node):
current_rank_id = local_gpu_id + gpus_per_node * node_id
current_rank = Rank(current_rank_id)
input_buffer = current_rank.get_input_buffer()
next_node_rank_id = (local_gpu_id + gpus_per_node * (node_id + 1)) % total_gpus
# Intra Node Exchange Data
for peer_gpu_id in range(gpus_per_node):
peer_rank_id = peer_gpu_id + gpus_per_node * node_id
peer_data_offset = peer_gpu_id * packets_per_gpu
if peer_gpu_id != local_gpu_id:
intra_node_memory_channels[(peer_rank_id, current_rank_id)].put_packets(
scratch_buffers[peer_rank_id][
local_gpu_id * packets_per_gpu : local_gpu_id * packets_per_gpu + packets_per_gpu
],
input_buffer[peer_data_offset : peer_data_offset + packets_per_gpu],
tb_group=thread_block_group,
)
# Intra Node Reduce
other_gpu_data = [
scratch_buffers[current_rank_id][
packets_per_gpu * gpu_idx : packets_per_gpu * gpu_idx + packets_per_gpu
]
for gpu_idx in range(gpus_per_node)
if gpu_idx != local_gpu_id
]
current_rank.reduce(
input_buffer[local_gpu_id * packets_per_gpu : local_gpu_id * packets_per_gpu + packets_per_gpu],
other_gpu_data,
tb_group=thread_block_group,
packet=True,
)
# Copy Reduced Data to Scratch Buffer and send to Next Node
current_rank.copy_packets(
scratch_buffers[current_rank_id][
local_gpu_id * packets_per_gpu : local_gpu_id * packets_per_gpu + packets_per_gpu
],
input_buffer[local_gpu_id * packets_per_gpu : local_gpu_id * packets_per_gpu + packets_per_gpu],
tb_group=thread_block_group,
)
inter_node_offset = total_gpus
inter_node_port_channels[current_rank_id].read_put_packets(
scratch_buffers[next_node_rank_id][
inter_node_offset
+ local_gpu_id * packets_per_gpu : inter_node_offset
+ local_gpu_id * packets_per_gpu
+ packets_per_gpu
],
scratch_buffers[current_rank_id][
local_gpu_id * packets_per_gpu : local_gpu_id * packets_per_gpu + packets_per_gpu
],
tb=0,
)
# Reduce Received Data from Remote Node
inter_node_data = [
scratch_buffers[current_rank_id][
inter_node_offset
+ local_gpu_id * packets_per_gpu : inter_node_offset
+ local_gpu_id * packets_per_gpu
+ packets_per_gpu
]
]
current_rank.reduce(
input_buffer[local_gpu_id * packets_per_gpu : local_gpu_id * packets_per_gpu + packets_per_gpu],
inter_node_data,
tb_group=thread_block_group,
packet=True,
)
# Broadcast Reduced Data
for peer_gpu_id in range(gpus_per_node):
peer_rank_id = peer_gpu_id + gpus_per_node * node_id
if peer_gpu_id != local_gpu_id:
intra_node_memory_channels[(peer_rank_id, current_rank_id)].put_packets(
scratch_buffers[peer_rank_id][
inter_node_offset
+ local_gpu_id * packets_per_gpu : inter_node_offset
+ local_gpu_id * packets_per_gpu
+ packets_per_gpu
],
input_buffer[
local_gpu_id * packets_per_gpu : local_gpu_id * packets_per_gpu + packets_per_gpu
],
tb_group=thread_block_group,
)
# Unpack Data Received from other GPUs in the same node
for peer_gpu_id in range(gpus_per_node):
if peer_gpu_id != local_gpu_id:
current_rank.unpack_packets(
input_buffer[
peer_gpu_id * packets_per_gpu : peer_gpu_id * packets_per_gpu + packets_per_gpu
],
scratch_buffers[current_rank_id][
inter_node_offset
+ peer_gpu_id * packets_per_gpu : inter_node_offset
+ peer_gpu_id * packets_per_gpu
+ packets_per_gpu
],
tb_group=thread_block_group,
)
print(JSON())
parser = argparse.ArgumentParser()
parser.add_argument("--name", type=str, help="name of the program")
parser.add_argument("--gpus_per_node", type=int, help="number of gpus per node")
parser.add_argument("--tbg_size", type=int, help="number of thread blocks in the thread block group")
parser.add_argument("--num_threads_per_block", type=int, default=1024, help="number of threads per block")
parser.add_argument("--min_message_size", type=int, default=0, help="minimum message size")
parser.add_argument("--max_message_size", type=int, default=2 * 2**20, help="maximum message size")
args = parser.parse_args()
allreduce_example(
args.name,
args.gpus_per_node,
args.tbg_size,
args.num_threads_per_block,
args.min_message_size,
args.max_message_size,
)