mirror of https://github.com/hpcaitech/ColossalAI
68 lines
4.0 KiB
Python
68 lines
4.0 KiB
Python
from .operator_handler import OperatorHandler
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from colossalai.tensor.sharding_spec import ShardingSpec
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from colossalai.auto_parallel.solver.sharding_strategy import ShardingStrategy, StrategiesVector
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from colossalai.tensor.shape_consistency import ShapeConsistencyManager
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from copy import deepcopy
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import math
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class ReshapeHandler(OperatorHandler):
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"""
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An OperatorHandler which deals with the sharding strategies of Reshape Operator, such as torch.reshape, torch.flatten, etc.
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"""
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def __init__(self, *args, **kwargs):
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super().__init__(*args, **kwargs)
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self.input_data = self.predecessor_node[0]._meta_data
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self.output_data = self.node._meta_data
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def _generate_compute_cost(self, *args, **kwargs):
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return super()._generate_compute_cost(*args, **kwargs)
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def register_strategy(self):
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# TODO: add strategies with more output sharding specs other than only fully replicated.
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input_node = self.strategies_vector.predecessor_nodes[0]
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# For reshape function, to keep the computing correctness we keep the sharding
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# spec of input is fully replicated. In addition, we will keep the output in
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# replica status and let the successor node choose the way to resharding the
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# output node. Therefore, the different strategies of input node with same
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# output sharding spec will generate same strategy for reshape function.
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sharding_spec_checklist = []
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for strategy in input_node.strategies_vector:
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# It looks a little bit confusing, the input of the processing node
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# is the output of the input_node.
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input_sharding_spec = strategy.output_sharding_spec
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assert isinstance(input_sharding_spec, ShardingSpec), f'The input node should NOT be a tuple of tensor.'
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if input_sharding_spec in sharding_spec_checklist:
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continue
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sharding_spec_checklist.append(input_sharding_spec)
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dim_partition_dict_for_output = {}
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output_sharding_spec = self._generate_sharding_spec(self.output_data, dim_partition_dict_for_output)
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name = f'{input_sharding_spec.sharding_sequence} -> FULLY REPLICATED'
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# TODO: use meta_info_prop to profile memory cost and compute cost
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compute_cost = 0
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memory_cost = self.node._meta_data.numel()
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# compute the communication cost, in reshape op, the communication happens during casting the input sharding spec to fully replicating.
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dim_partition_dict_for_replicate_input = {}
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replicate_input_sharding_spec = self._generate_sharding_spec(self.input_data,
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dim_partition_dict_for_replicate_input)
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# shape consistency manager is a singleton class
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shape_consistency_manager = ShapeConsistencyManager()
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_, _, communication_cost = shape_consistency_manager.shape_consistency(input_sharding_spec,
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replicate_input_sharding_spec)
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# generate resharding cost
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resharding_costs = self._generate_resharding_costs([input_sharding_spec])
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# to prevent the resharding happening, set their resharding cost to inf.
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resharding_costs[input_node] = [0 if cost == 0 else math.inf for cost in resharding_costs[input_node]]
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sharding_strategy = ShardingStrategy(name,
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output_sharding_spec,
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compute_cost=compute_cost,
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communication_cost=communication_cost,
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memory_cost=memory_cost,
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resharding_costs=resharding_costs,
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input_shardings=[input_sharding_spec])
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self.strategies_vector.append(sharding_strategy)
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