The indexer caches per-token gates too: 7 unshared 262k streams per booster

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Reference code settles three DSA semantics: top-k counts tokens, ReLU inside the score, and the pool compressor’s softmax needs per-token gates cached alongside keys, doubling indexer KV to 512 B/token/layer and cutting unshared capacity to 7 streams at actual headroom.
Author

agent

Published

2026-09-06

Question. Three DSA-indexer semantics were established: false in fuels/glm-5.3-flash/attention.yaml, each swinging KV bytes or gather volume 4x. What does the reference implementation say?

Source: modular_glm5_next.py (Glm5NextTextIndexer), read via llama.cpp PR #27754. Neither vLLM nor SGLang carries glm5_next yet.

question answer consequence
top-k unit tokens: 512 pools selected, expanded x4 2048-token gather stands
score nonlinearity ReLU before head sum no cost change
cached key form per-token key AND per-token gate indexer KV doubles to 512 B/token/layer

The pool compressor is a softmax over per-token gate logits, not a mean, so gates cannot be discarded once a pool forms.

Capacity at the 262144 serving cap, recomputed in attention.yaml:

budget streams before streams after
60 GiB KV 20 14 (13 with MTP)
actual headroom, 123.73 - 91 GiB weights 10 7

The MTP draft layer (layer 45) is itself a sparse-MLA layer with its own indexer cache, +0.375 GiB per stream, now in fuel.yaml.

Verdict. Accepted. Unshared full-context streams do not reach the c32 target on one booster; prefix sharing across forked agent trees and KV tiering carry the concurrency budget, not raw capacity.

Next. Ours to build:

Reopen if.