Efficiency Frontiers › Key Parameters

Michael BrenndoerferMarch 16, 20261 min read
Language AI HandbookAll chapters
Part 67 of 67Frontier Outlook from 2025
Chapter 509Efficiency Frontiers › Key Parameters
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The key parameters for the efficiency techniques covered in this chapter are:

  • Quantization bits: Controls the tradeoff between precision and memory. 8-bit is nearly lossless; 4-bit requires careful calibration; 2-bit degrades quality significantly.
  • KV heads (GQA): Number of key-value groups. Full MHA uses HH heads; MQA uses 1; GQA uses an intermediate value (4-8 is common). Reduces KV-cache memory proportionally.
  • Speculative decoding k: Number of draft tokens per round. Larger kk increases potential speedup but also wastes more compute when tokens are rejected.
  • Gradient checkpointing interval: Layers between saved checkpoints. Checkpointing every L\sqrt{L} layers is theoretically optimal; in practice, checkpointing every layer or every other layer is common.
  • Expert count and top-k (MoE): Total experts and how many are active per token. Common choices are 8 experts with top-2 or 64 experts with top-2. Increasing experts increases total capacity without increasing active FLOPs.
  • FlashAttention tile size: Determined automatically based on SRAM size; controlled implicitly by block size hyperparameter in FlashAttention implementations.