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Blog: Add Office Hours #51 recap — Speculators v0.5 and sparse MLA#247

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Blog: Add Office Hours #51 recap — Speculators v0.5 and sparse MLA#247
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@soyr-redhat soyr-redhat commented Jun 16, 2026

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Summary

  • Recap of vLLM Office Hours {#} 51 (June 11, 2026), covering the Speculators v0.5 update and an engineering spotlight on accelerating sparse MLA via masked MHA
  • Speculators section covers new drafting algorithms (DFlash, P-Eagle, Fast MTP), hidden states extraction (online/offline), and GuideLLM-based evaluation
  • Sparse MLA section covers the three-tier strategy (Dense MHA / Masked MHA / Sparse MQA) for DeepSeek models, with up to 2x prefill speedup in the moderate sequence length band
  • Includes 5 figures extracted from the slide deck

Authors

Sawyer Bowerman (@soyr-redhat)

Based on presentations by Michael Goin, Fynn Schmitt-Ulms, Helen Zhao, and Matt Bonanni.

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Training speculator models requires hidden states from the target model. Speculators now supports a new extraction system with two primary modes:

**Online training:** The vLLM server extracts hidden states and sends them directly to the training process in real time via NCCL. This keeps the pipeline simple and avoids disk I/O.

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P2 Badge Fix the online-training transport description

Readers trying to reproduce Speculators v0.5 online training will look for direct NCCL transfer and assume disk I/O is avoided, but the v0.5 release post in this repo describes the current path as REST requests to vLLM with hidden states temporarily written to disk/ram disk (_posts/2026-05-28-speculators-v050.md lines 91-99), and the public tutorial uses --vllm-endpoint, --on-missing generate, and --on-generate delete. Please describe this as on-demand file-backed extraction unless NCCL support has actually landed and the rest of the docs are being updated too.

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### How MLA works

MLA compresses the KV cache by projecting keys and values into a shared latent space. In DeepSeek models, this reduces the cached representation from dimension 16,384 down to 512, a 57x reduction. There are two mathematically equivalent ways to compute MLA:

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P2 Badge Fix the MLA compression arithmetic

The numbers in this sentence do not yield the claimed reduction: 16,384 / 512 is 32x, not 57x. If the intent is the usual DeepSeek MLA KV-cache comparison, it needs to count both K and V plus the decoupled RoPE key, i.e. 32,768 elements down to 576 elements (512 + 64), which is about 57x; otherwise the published post will give readers internally inconsistent dimensions.

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Covers the Speculators v0.5 update (DFlash, P-Eagle, Fast MTP,
hidden states extraction) and Matt Bonanni's engineering spotlight
on accelerating sparse MLA via masked MHA in DeepSeek models.

Signed-off-by: Sawyer Bowerman <sbowerma@redhat.com>
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