Feat: Activation Checkpointing#154
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| @@ -1,12 +1,15 @@ | |||
| #include "infini_train/include/nn/modules/transformer/transformer.h" | |||
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之后扩展 recompute 其他功能（如selective）的话就不适合全放在transformer.cc里了，之后可以拆分activation_recompute.cc。本PR可以不做修改
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确实，这块确实没太想清楚，主要是 megatron 的实现里面也把很多重计算逻辑融在了 transformer 模型层，之后可以再讨论下
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chen2021673
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Jun 25, 2026
| // Used by non-reentrant checkpoint recomputation so downstream SetupContext | ||
| // calls see the same needs_input_grad_ pattern as the original forward, | ||
| // without wiring the recompute graph into the engine. | ||
| class PropagateRequiresGradGuard { |
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本质上是需要一个 2*2=4 种情况的精细控制（with_grad/no_grad x 带引用计数建图/仅传递 requires_grad）。
也可以不单独实现一个 guard，而是给原先的 GradGuard 重载一个带参数 (比如 bool record_context = false) 的构造方式，让 GradGuard 本身能够覆盖这四种情况。
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Jun 25, 2026
| try { | ||
| forward_fn(detached_inputs); | ||
| } catch (const StopRecomputeError &) { | ||
| // Early-stop: expected when all needed tensors are recomputed. |
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只是用异常的语法和控制流机制来实现 early stop 的语义，本质上并不是真的抛一个会让程序 abort 的异常。torch 也采取的是一样的实现方式。
这块暂时没有想到其他更优雅的处理方式。
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