deepspeed.initialize() returns a training engine in its first argument
DeepSpeedEngine. This engine is used to progress training:
for step, batch in enumerate(data_loader): #forward() method loss = model_engine(batch) #runs backpropagation model_engine.backward(loss) #weight update model_engine.step()
- deepspeed.DeepSpeedEngine.forward(*args, **kwargs)¶
Defines the computation performed at every call.
Should be overridden by all subclasses.
Although the recipe for forward pass needs to be defined within this function, one should call the
Moduleinstance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.
- deepspeed.DeepSpeedEngine.backward(*args, **kwargs)¶
- deepspeed.DeepSpeedEngine.step(self, lr_kwargs=None)¶
Execute the weight update step after forward and backward propagation on effective_train_batch.
Query whether the current micro-batch is at the boundary of gradient accumulation, and thus will trigger gradient reductions and an optimizer step.
if the current step is a gradient accumulation boundary.
- Return type
- deepspeed.DeepSpeedEngine.save_16bit_model(self, save_dir, save_filename='pytorch_model.bin')¶
Save 16bit model weights
This method saves the 16bit model weights at the desired destination.
save_dir – Required. Directory for saving the model
save_filename – Optional. Filename to save to. Defaults to
Truewhen a model has been saved,
Falseotherwise. It will not be saved if stage3_gather_16bit_weights_on_model_save is
Important: all processes must call this method and not just the process with rank 0. It is because the processes need to work in sync to gather the weights. This method will hang waiting to synchronize with other processes if it’s called just for the process with rank 0.
Additionally when a DeepSpeed checkpoint is created, a script
zero_to_fp32.py is added there which can be used to reconstruct fp32 master weights into a single pytorch