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mindspore.nn.AdaSumByGradWrapCell

class mindspore.nn.AdaSumByGradWrapCell(optimizer)

Enable the adasum in “auto_parallel/semi_auto_parallel” mode. The implementation of the Adaptive Summation (AdaSum) algorithm is calculated by gradients. See the paper AdaSum: Scaling Distributed Training with Adaptive Summation.

$$\begin{array}{r}\begin{array}{l}{w}_{t+1}=w_t-\alpha \cdot Adasum(g_1,g_2)\\ w_{t+1}=w_t-\alpha \cdot [(1-\frac{g_2^T\cdot g_1}{2\cdot {\Vert g_1\Vert }^2})\cdot g_1+(1-\frac{g_1^T\cdot g_2}{2\cdot {\Vert g_2\Vert }^2})\cdot g_2]\end{array}\end{array}$$

In this implementation, $g$ represents the gradient of the weights, and the subscripts represent different devices in the data-parallel dimension.

Note

When using AdaSum, the number of traning cards needs to be a power of 2 and at least 16 cards are required. Currently, the optimizer sharding and pipeline parallel is not supported when using AdaSum. It is recommended to using AdaSumByGradWrapCell in semi auto parallel/auto parallel mode. In data parallel mode, we recommend to using mindspore.boost to applying AdaSum.

Parameters

optimizer (Union[Cell]) – Optimizer for updating the weights. The construct function of the optimizer requires only one input.

Inputs:

• grads (Tuple(Tensor)) - Tuple of gradients, same with the input of passed optimizer.

Raises

• RuntimeError – If parallel_mode uses stand_alone mode, AdaSum only supports use in distributed scenarios.

• RuntimeError – If the optimizer parallel is used when using AdaSum.

• RuntimeError – If the pipeline parallel is used when using AdaSum.

• RuntimeError – If device_num is not a power of 2, or less than 16.

Supported Platforms:

Ascend GPU

Examples

>>> import mindspore as ms
>>> from mindspore import nn
>>> # Define the network structure of LeNet5. Refer to
>>> # https://gitee.com/mindspore/docs/blob/r2.2/docs/mindspore/code/lenet.py
>>> net = LeNet5()
>>> optim = nn.AdaSumByGradWrapCell(nn.Momentum(params=net.trainable_params(), learning_rate=0.1, momentum=0.9))
>>> loss = nn.SoftmaxCrossEntropyWithLogits()
>>> model = ms.train.Model(net, loss_fn=loss, optimizer=optim, metrics=None)