[DeepSpeed ZeRO3] Fix performance degradation in sharded models (#18911)

* [DeepSpeed] Fix performance degradation in sharded models

* style

* polish

Co-authored-by: Stas Bekman <stas@stason.org>
This commit is contained in:
Olatunji Ruwase 2022-09-07 10:44:20 -04:00 committed by GitHub
parent 10c774cf60
commit 3059d80d80
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@ -421,12 +421,17 @@ def _load_state_dict_into_model(model_to_load, state_dict, start_prefix):
if is_deepspeed_zero3_enabled():
import deepspeed
# because zero3 puts placeholders in model params, this context
# manager gathers (unpartitions) the params of the current layer, then loads from
# the state dict and then re-partitions them again
with deepspeed.zero.GatheredParameters(list(module.parameters(recurse=False)), modifier_rank=0):
if torch.distributed.get_rank() == 0:
module._load_from_state_dict(*args)
# In sharded models, each shard has only part of the full state_dict, so only gather
# parameters that are in the current state_dict.
named_parameters = dict(module.named_parameters(prefix=prefix[:-1], recurse=False))
params_to_gather = [named_parameters[k] for k in state_dict.keys() if k in named_parameters]
if len(params_to_gather) > 0:
# because zero3 puts placeholders in model params, this context
# manager gathers (unpartitions) the params of the current layer, then loads from
# the state dict and then re-partitions them again
with deepspeed.zero.GatheredParameters(params_to_gather, modifier_rank=0):
if torch.distributed.get_rank() == 0:
module._load_from_state_dict(*args)
else:
module._load_from_state_dict(*args)