~/talk

Optimus: Accelerating Large-Scale Multi-Modal LLM Training by Bubble Exploitation

Talkat USENIX ATC '25 · 2025-07-07..07-09· [large-language-models, machine-learning]
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linkedin:linhaibin
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Reports a system called Optimus that cuts end-to-end MLLM training time by ~20.5–21.3% on 3,072 GPUs (ViT-22B encoder + GPT-175B backbone) by turning idle GPU bubbles into useful work. It places encoder and LM states on every GPU via separate parallel plans, uses a greedy bubble-scheduling algorithm with global ordering, and decomposes encoder layers to kernel-level scheduling to fill sub-millisecond (~300 µs) tensor-parallel gaps. Compares vs Megatron, FSDP, APA.

AI-written summary · about

  1. 0:00Optimus introduction
  2. 1:24Multimodal LLM challenges
  3. 3:31Exploiting GPU idle time
  4. 5:57Optimus design: encoder & LM states
  5. 8:27Scheduling complex dependencies
  6. 10:32Kernel-level scheduling
  7. 11:37Performance evaluation
  8. 14:03Summary
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