mirror of https://github.com/hpcaitech/ColossalAI
66 lines
2.8 KiB
Python
66 lines
2.8 KiB
Python
from typing import List, Tuple
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import torch
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from colossalai._analyzer._subclasses.flop_tensor import flop_mapping
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from colossalai._analyzer.fx.node_util import compute_size_in_bytes as activation_size
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from colossalai.auto_parallel.tensor_shard.sharding_strategy import MemoryCost, TrainCycleItem
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from ..registry import meta_register
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__all__ = ["where_meta_info"]
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@meta_register.register(torch.where)
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def where_meta_info(*args, **kwargs) -> Tuple[TrainCycleItem, TrainCycleItem, List[torch.Tensor]]:
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"""torch.where meta information generator
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Returns:
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Tuple[TrainCycleItem, TrainCycleItem, List[torch.Tensor]]: compute cost, memory cost and forward inputs
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"""
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condition_tensor, x_tensor, y_tensor, output_tensor = [arg.data for arg in args]
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# compute cost
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fwd_compute_cost = 0
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# if we need to broadcast the condition tensor, during backward we need to do a reduce_sum
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bwd_compute_cost = 0
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if x_tensor.shape != output_tensor.shape:
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bwd_compute_cost += flop_mapping[torch.ops.aten.sum.dim_IntList]([output_tensor], [x_tensor])
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if y_tensor.shape != output_tensor.shape:
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bwd_compute_cost += flop_mapping[torch.ops.aten.sum.dim_IntList]([output_tensor], [y_tensor])
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compute_cost = TrainCycleItem(fwd=fwd_compute_cost, bwd=bwd_compute_cost, total=fwd_compute_cost + bwd_compute_cost)
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# memory cost
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# during the forward phase, torch.where will allocate memory for output tensor and condition tensor
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# during the backward phase, torch.where will allocate temp memory which is 3 times as output tensor, then generate
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# gradient matrix for input x and input y, remove the temp memory and condition tensor generated in forward phase
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# NOTE: currently in SPMD solver we always believe that there will be a new input tensor created in forward
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fwd_mem_cost = MemoryCost(activation=activation_size([condition_tensor, x_tensor, y_tensor, output_tensor]))
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bwd_mem_cost = MemoryCost(
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activation=activation_size([x_tensor, y_tensor]) - activation_size([condition_tensor]),
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parameter=0,
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temp=activation_size([output_tensor]) * 3
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+ activation_size([condition_tensor])
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- activation_size([x_tensor, y_tensor]),
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buffer=0,
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)
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total_mem_cost = MemoryCost(
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activation=fwd_mem_cost.activation + bwd_mem_cost.activation,
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parameter=fwd_mem_cost.parameter + bwd_mem_cost.parameter,
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temp=fwd_mem_cost.temp + bwd_mem_cost.temp,
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buffer=fwd_mem_cost.buffer + bwd_mem_cost.buffer,
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)
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memory_cost = TrainCycleItem(fwd=fwd_mem_cost, bwd=bwd_mem_cost, total=total_mem_cost)
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# store fwd_in, fwd_buffer, fwd_out
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fwd_in = [condition_tensor]
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fwd_buffer = []
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fwd_out = [output_tensor]
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return compute_cost, memory_cost, fwd_in, fwd_buffer, fwd_out
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