Gradient Checkpointing and Activation Recomputation
Backprop keeps every intermediate activation. At 70B parameters and 128K context that is 3 TB of activations per rank. Checkpointing trades FLOPs for memory: recompute instead of save. The question is which segments to drop, and the answer is not "all of them."
Visual edition planned
This lesson isn’t interactive yet.
It is part of the curriculum and will get the same treatment as Phase 1 — a visual cover, hands-on labs, derivations with numeric checks and a quiz. Until then, the original lesson is the best place to read it:
Part of Phase 10 — LLMs from Scratch. Use the previous / next cards below to keep browsing the phase.