Decoder block

Pinned implementation and paper LDLM @ e18c42a, not yet public · arXiv:2605.07933v1 · OpenWebText · 1024 · checkpoint, tokenizer and saved statistics not verified · How to read

in
rnr_n [B batch, T positions, 768 d]zpz^{p} [B batch, T positions, 768 d]
out
rn+1r_{n+1} [B batch, T positions, 768 d]
parameters
8,264,580 · × 6 blocks = 49,587,480
Parameters

8,264,580 parameters per block, across its learned components

Exact per-instance accounting
ComponentCalculationParameters
Perceiver attention3,540,608 across its components3,540,608
Residual scale1+11 + 12
MLP4,723,968 across its components4,723,968
Residual scale1+11 + 12
Per-instance total8,264,580

Across 6 independent blocks: 8,264,580×6=49,587,4808{,}264{,}580 \times 6 = 49{,}587{,}480 parameters.

Derived from the pinned implementation’s constructors and configuration. The checkpoint’s tensors have not been counted. 306,011,162 of these parameters are trained; frozen GPT-2 and the decoder’s mask vector, 124,442,112, are not.

Explanation

It is the encoder’s block with the two streams exchanged, and with a learned scale on each update.

Sources4

Direct evidence

A decoder block: Perceiver attention with the queries’ stream first read from the decoder’s state and keys and values from the latents and the state, a scaled residual, an MLP and a second scaled residual.

The implementation, pinned at revision e18c42acdfb7, not yet public

Direct evidence

Every query is the mask vector: it passes the MLP and a scale, positions are added; the latents take the same position table; the blocks are applied; every position counts as masked.

The implementation, pinned at revision e18c42acdfb7, not yet public

Direct evidence

The decoder’s residual scale: x · (1 + s), with one learned scalar for masked positions and one for unmasked ones, both zero at initialization.

The implementation, pinned at revision e18c42acdfb7, not yet public

Direct evidence

The latent decoder: 12 heads of 64 features, query and key normalization, softcap 50, 6 layers, MLP multiplier 4; the token decoder has 3 blocks.

The implementation, pinned at revision e18c42acdfb7, not yet public