对于像fc2这种需要对输出结果做reduce-scatter的情况,除了p2p形式的overlap,megatron还提供了另外一种overlap的方法:pipeline chunk。 Pipeline chunk的思想是:假设原来是做完gemm(A, B)后再对结果reduce-scatter,那么现在我可以把矩阵(比如A)拆分成若干chunk,每次等gemm(chunk_i, B)的结果出来后,把这个结果发出去做...
在使用Distributed Optimizer进行分布式训练时,各DP Rank间需要进行梯度同步,引入了额外的梯度的reduce-scatter和更新参数的all-gather通信。在Megatron中,通过设置overlap_grad_sync=true和overlap_param_sync=true启用重叠技术后,这些DP通信会按单个TransformerLayer或单个Virtual Pipeline的粒度进行分块并与计算进行重叠,使通...
图3. 使用 NVIDIA H100 GPU 和 BF16 精度的 Nemotron-4 15B,对其执行--overlap-grad-reduce优化的效果。 在Megatron-Core v0.6 版本中,我们引入了分布式优化器支持,其中优化器状态在数据并行副本上分割,从而减少峰值内存占用。分布式优化器还将之前需要的梯度 all-reduce 分解为梯度 reduce-sc...
单独开启Grad Reduce以及Param Gather的overlap效果不明显,但通过结合TP Comm Overlap,能将训练吞吐进一步提升至201.3TFLOP/s/GPU,相对于基线有17%的提升 LLM训练加速应用指南 预训练&微调命令统一描述 ENV=$1 # 运行环境配置开关: dsw单机训练训练,dlc表示多机训练环境 MODEL_SIZE=$2 # 模型结构参数量级: 8B, ...
单独开启Grad Reduce以及Param Gather的overlap效果不明显,但通过结合TP Comm Overlap,能将训练吞吐进一步提升至201.3TFLOP/s/GPU,相对于基线有17%的提升 LLM训练加速应用指南 预训练&微调命令统一描述 ENV=$1 # 运行环境配置开关: dsw单机训练训练,dlc表示多机训练环境 ...
overlap_grad_reduce ... False overlap_p2p_comm ... False override_opt_param_scheduler ... False params_dtype ... torch.float16 patch_dim ... 16 perform_initialization ... True pipeline_model_parallel_size ...
zero_grad() if args.fp16: optimizer.backward(loss, update_master_grads=False) else: loss.backward() DeepSpeed会在使用小批量更新权重后自动处理梯度清零。此外,DeepSpeed在内部解决了分布式数据并行和FP16,简化了多个地方的代码。 (A) DeepSpeed 还在梯度累积边界处自动执行梯度平均,因此我们跳过allreduce通信...
We use two types of parallelism: data and model parallelism. We facilitate two distributed data parallel implementations: a simple one of our own that performs gradient all-reduce at the end of back propagation step, and Torch's distributed data parallel wrapper that overlaps gradient reduction wit...
To reduce GPU memory usage when training a large model, we support various forms of activation checkpointing and recomputation. Instead of all activations being stored in memory to be used during backprop, as was traditionally the case in deep learning models, only activations at certain "checkpoi...
pm.register_patch('megatron.core.tensor_parallel.layers.linear_with_grad_accumulation_and_async_allreduce', linear_with_grad_accumulation_and_async_allreduce_moe) if args.use_pipe_experts: from .core.distributed.param_and_grad_buffer import pipe_register_grad_ready pm.register_...