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paddlepaddle--paddle/python/paddle/distributed/passes/auto_parallel_master_grad.py
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2026-07-13 12:40:42 +08:00

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# 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.
from __future__ import annotations
import copy
import logging
from collections import OrderedDict
from typing import TYPE_CHECKING
import paddle
from paddle.distributed.auto_parallel.static.utils import (
is_backward_op,
is_gradient_clip_op,
is_optimize_op,
naive_set_dist_op_attr_for_program_by_mesh_and_mapping,
set_var_dist_attr,
)
from paddle.distributed.fleet.meta_optimizers.common import (
OP_ROLE_KEY,
OpRole,
)
from paddle.framework import core
from paddle.static import program_guard
from ..utils.log_utils import get_logger
from .pass_base import PassBase, register_pass
if TYPE_CHECKING:
from paddle.base import Variable
_supported_optimizer_type = [
"adam",
"adamax",
"adamw",
"decayed_adagrad",
"momentum",
"dgc_momentum",
"lars_momentum",
"merged_momentum",
"lamb",
"sgd",
]
logger = get_logger(logging.INFO, "MasterGradPass")
def _is_master_grad_cast_op(block, op):
op_name = op.type
if op_name != "cast":
return False
input_names = op.input_arg_names
output_names = op.output_arg_names
assert len(input_names) == 1
assert len(output_names) == 1
input_var_name = input_names[0]
return (
"@master_grad_fp16" in input_var_name
or "@master_grad_bf16" in input_var_name
)
def get_output_in_varlist(op, var_names) -> list[str]:
grad_names = []
for output_name in op.output_arg_names:
if output_name in var_names:
grad_names.append(output_name)
return grad_names
@register_pass("auto_parallel_master_grad_pass")
class MasterGradPass(PassBase):
"""
Use the high precision gradient to replace the low precision gradient in optimizer to avoid inf/nan values of low precision.
The high precision gradient 'master grad' will be used by communication operator, `update_loss_scaling`, `GradClip` and `optimizer`.
"""
def __init__(self):
super().__init__()
def _check_self(self):
return True
def _check_conflict(self, other_pass):
return True
def _apply_single_impl(self, main_program, startup_program, context):
self._completer = self.get_attr("completer")
dist_context = self.get_attr("dist_context")
params_grads = self.get_attr("params_grads")
logger.debug(f"Origin main_program: {main_program}")
self._add_master_grad(main_program, params_grads, dist_context)
self._regenerate_optimizer(
main_program, startup_program, params_grads, dist_context
)
logger.debug(f"After main program: {main_program}")
def _add_cast_op(self, cur_block, grad_names: list[str], dist_context):
grad_first_ids = OrderedDict()
for idx, op in enumerate(cur_block.ops):
if is_optimize_op(op):
break
elif is_backward_op(op):
var_names = get_output_in_varlist(op, grad_names)
for var_name in var_names:
if var_name not in grad_first_ids:
grad_first_ids[var_name] = idx
# Communication operators such as 'allreduce_sum' use input var as output.
else:
pass
# insert cast op
for grad_name, idx in reversed(grad_first_ids.items()):
grad_var = cur_block.var(grad_name)
if (
grad_var.dtype == paddle.float16
or grad_var.dtype == paddle.bfloat16
):
is_fp16 = grad_var.dtype == paddle.float16
producer_op = cur_block.ops[idx]
producer_op_dist_attr = (
dist_context.get_op_dist_attr_for_program(producer_op)
)
assert producer_op_dist_attr is not None, (
f"The op: '{producer_op}' should be distributed"
)
ref_output_dist_attr = (
producer_op_dist_attr.get_output_dist_attr(grad_name)
)
assert ref_output_dist_attr is not None, (
f"The output: '{grad_name}' should be distributed"
)
ref_mesh = ref_output_dist_attr.process_mesh
ref_dims_mapping = ref_output_dist_attr.dims_mapping
ref_chunk_id = producer_op_dist_attr.chunk_id
grad_half_precision_name = (
grad_name + '@master_grad_fp16'
if is_fp16
else grad_name + '@master_grad_bf16'
)
grad_half_precision = cur_block.create_var(
name=grad_half_precision_name,
dtype=grad_var.dtype,
shape=grad_var.shape,
persistable=False,
stop_gradient=False,
)
set_var_dist_attr(
dist_context,
grad_half_precision,
ref_dims_mapping,
ref_mesh,
chunk_id=ref_chunk_id,
)
producer_op_dist_attr = (
dist_context.get_op_dist_attr_for_program(producer_op)
)
origin_out_dims_mapping = (
producer_op_dist_attr.get_output_dims_mapping(grad_name)
)
producer_op._rename_output(grad_name, grad_half_precision.name)
producer_op_dist_attr.set_output_dims_mapping(
grad_half_precision.name, origin_out_dims_mapping
)
grad_var.desc.set_dtype(core.VarDesc.VarType.FP32)
cast_op = cur_block._insert_op_without_sync(
idx + 1,
type="cast",
inputs={"X": grad_half_precision},
outputs={"Out": grad_var},
attrs={
"in_dtype": grad_half_precision.dtype,
"out_dtype": grad_var.dtype,
},
)
cast_op._set_attr(OP_ROLE_KEY, OpRole.Backward)
naive_set_dist_op_attr_for_program_by_mesh_and_mapping(
cast_op,
ref_mesh,
ref_dims_mapping,
dist_context,
chunk_id=ref_chunk_id,
)
cur_block._sync_with_cpp()
def _regenerate_optimizer(
self,
main_program,
startup_program,
params_grads: list[tuple[Variable, Variable]],
dist_context,
):
grad_names = [g.name for _, g in params_grads]
# 1. delete the origin optimizer op
# 1.1 delete the var and op associated with the optimizer op in main_program
main_ops = main_program.global_block().ops
main_ops_len = len(main_ops)
first_optimize_idx = main_ops_len
for idx, op in enumerate(main_ops):
# We don't delete the operators for check_nan_inf
if is_optimize_op(op) and is_gradient_clip_op(op):
first_optimize_idx = idx
break
assert first_optimize_idx < main_ops_len, (
"The first optimizer op is not found!"
)
deleted_temp_var_names = []
deleted_persist_var_names = []
reserved_var_names = []
for idx in range(main_ops_len - 1, first_optimize_idx - 1, -1):
op = main_ops[idx]
inout_arg_names = op.input_arg_names + op.output_arg_names
if op.type in _supported_optimizer_type:
param_names = op.input("Param")
skip_update_names = op.input("SkipUpdate")
for reserved_name in param_names + skip_update_names:
if reserved_name not in reserved_var_names:
reserved_var_names.append(reserved_name)
for input_name in inout_arg_names:
if input_name in grad_names:
continue
var = main_program.global_block().var(input_name)
if (
var.persistable
and input_name not in deleted_persist_var_names
):
deleted_persist_var_names.append(input_name)
elif (
not var.persistable
and input_name not in deleted_temp_var_names
):
deleted_temp_var_names.append(input_name)
main_program.global_block()._remove_op(idx)
for var_name in deleted_temp_var_names + deleted_persist_var_names:
if var_name not in reserved_var_names:
main_program.global_block()._remove_var(var_name)
main_program.global_block()._sync_with_cpp()
# 1.2 delete the var and op in startup_program
for reserved_name in reserved_var_names:
if reserved_name in deleted_persist_var_names:
deleted_persist_var_names.remove(reserved_name)
startup_global_block = startup_program.global_block()
for var_name in deleted_persist_var_names:
if startup_global_block.has_var(var_name):
startup_global_block._remove_var(var_name)
for idx, op in reversed(list(enumerate(startup_global_block.ops))):
inout_arg_names = op.input_arg_names + op.output_arg_names
for var_name in inout_arg_names:
if var_name in deleted_persist_var_names:
startup_program.global_block()._remove_op(idx)
break
# 2. re-generate new optimizer op
serial_optimizer = copy.deepcopy(dist_context._serial_optimizer)
serial_optimizer._learning_rate = (
dist_context._serial_optimizer._learning_rate
)
serial_optimizer._sorted = False
with (
program_guard(main_program, startup_program),
main_program.switch_name_generator_guard("opt_"),
):
_ = serial_optimizer.apply_gradients(params_grads)
self._completer.complete_update_annotation(main_program)
def _add_master_grad(self, main_program, params_grads, dist_context):
grad_names = [g.name for _, g in params_grads]
for sub_block in main_program.blocks:
self._add_cast_op(sub_block, grad_names, dist_context)