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2026-07-13 12:40:42 +08:00

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Python

# Copyright (c) 2023 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import collections
import logging
from ..auto_parallel.static.utils import (
get_logger,
)
from .pass_base import PassBase, register_pass
from .pass_utils import AutoParallelStreamType, split_matmul_grad_to_matmul
logger = get_logger(logging.INFO)
# For allreduce pattern in the backward phase of column parallel linear:
# dX, dY = matmul_grad(X, Y, dOut)
# dX = all_reduce_sum(dX)
# Split matmul_grad to 2 matmul:
# dX = matmul(dOut, Y^T)
# dX = all_reduce_sum(dX)
# dY = matmul(X^T, dOut)
#
# Then the all_reduce sum can overlap with the compute of dY.
@register_pass("allreduce_matmul_grad_overlapping")
class AllreduceMatmulGradOverlappingPass(PassBase):
def __init__(self):
super().__init__()
self.op_namescope = "/auto_parallel/allreduce_matmul_grad_overlapping"
self.set_attr("dist_context", None)
def _check_self(self):
if self.get_attr("dist_context") is None:
return False
return True
def _check_conflict(self, other_pass):
return True
def _apply_single_impl(self, main_program, startup_program, context):
self.dist_context = self.get_attr("dist_context")
block = main_program.global_block()
matmul_grad_id_to_allreduce_id = (
self._get_all_matmul_grad_and_allreduce_pairs(block)
)
logger.info(
f"overlap matmul_grad and allreduce: {matmul_grad_id_to_allreduce_id}"
)
self._split_matmul_grad_and_multi_streaming_allreduce(
block, matmul_grad_id_to_allreduce_id
)
def _get_all_matmul_grad_and_allreduce_pairs(self, block):
ops = block.ops
op_num = len(ops)
matmul_grad_id_to_allreduce_id = collections.OrderedDict()
for i, op_i in enumerate(ops):
if (
op_i.type == 'matmul_v2_grad'
and op_i.attr("trans_x") is False
and op_i.attr("trans_y") is False
):
x_grad = op_i.output("X@GRAD")
for j in range(i + 1, op_num):
op_j = ops[j]
if (
op_j.type == 'c_allreduce_sum'
and op_j.input("X") == x_grad
):
matmul_grad_id_to_allreduce_id[i] = j
return matmul_grad_id_to_allreduce_id
def _split_matmul_grad_and_multi_streaming_allreduce(
self, block, matmul_grad_id_to_allreduce_id
):
ops = block.ops
for matmul_grad_id, allreduce_id in reversed(
matmul_grad_id_to_allreduce_id.items()
):
matmul_grad_op = ops[matmul_grad_id]
allreduce_op = ops[allreduce_id]
# NOTE(Sonder): When there are ops between matmul_grad and allreduce, we should check whether
# these ops rely on the output of the intermediate ops. If so, we should not split the matmul_grad.
# Otherwise, the output of the intermediate ops will get wrong results.
skip_overlapping = False
moved_ops_output = []
matmul_grad_output = matmul_grad_op.output('Y@GRAD')[0]
for idx in range(matmul_grad_id + 1, allreduce_id):
if matmul_grad_output in ops[idx].desc.input_arg_names():
moved_ops_output.extend(ops[idx].desc.output_arg_names())
else:
for input_name in ops[idx].desc.input_arg_names():
if input_name in moved_ops_output:
skip_overlapping = True
if skip_overlapping:
continue
# matmul_grad_op => matmul_v2 + reshape + reshape + matmul_v2 + reshape
split_matmul_grad_to_matmul(
block, matmul_grad_id, self.dist_context, self.op_namescope
)
# NOTE(Ruibiao): Required OP scheduling order: matmul(dOut, Y^T) -> all_reduce_sum(dX) -> matmul(X^T, dOut).
# all_reduce_sum(dX) and matmul(X^T, dOut) cannot be swapped. Otherwise, after buffer_shared_inplace_pass
# adding share_buffer OP before all_reduce_sum, all_reduce_sum will synchronous with comp-stream, and then
# the matmul op before it cannot be overlapped.
allreduce_op_dist_attr = (
self.dist_context.get_op_dist_attr_for_program(allreduce_op)
)
allreduce_op_dist_attr.execution_stream = (
AutoParallelStreamType.MP_STREAM.value
)
allreduce_op_inputs = allreduce_op.desc.input_names()
allreduce_op_outputs = allreduce_op.desc.output_names()
allreduce_op_inputs = {
name: allreduce_op.input(name) for name in allreduce_op_inputs
}
allreduce_op_outputs = {
name: allreduce_op.output(name) for name in allreduce_op_outputs
}
# matmul_v2 + reshape + reshape + matmul_v2 + reshape + ... + original all_reduce_sum
# =>
# matmul_v2 + new all_reduce_sum + reshape + reshape + matmul_v2 + reshape + ... + original all_reduce_sum
#
# NOTE(liym27): new all_reduce_sum must be inserted to "the next of the first matmul_v2", otherwise another
# pass fused_linear_param_grad_add will not work.
allreduce_op = block._insert_op_without_sync(
index=matmul_grad_id + 1,
type=allreduce_op.type,
inputs=allreduce_op_inputs,
outputs=allreduce_op_outputs,
attrs=allreduce_op.all_attrs(),
)
self.dist_context.set_op_dist_attr_for_program(
allreduce_op, allreduce_op_dist_attr
)
# Remove the original allreduce op
block._remove_op(allreduce_id + 5, sync=False)
block._sync_with_cpp()