Organizations: University of Wisconsin-Madison Madison, Wisconsin, USA · Korea University Seoul, Republic of Korea · NVIDIA Santa Clara, California, USA
We introduce FORGE (Fast On-chip Rotor Generation for Experts), a procedural weight generation system for Sparse Mixture-of-Experts (MoE) inference. Rather than storing and loading every expert weight tensor from HBM, we show how a compact accelerator inside each Streaming Multiprocessor can regenerate them on-the-fly from O(log2d) rotor parameters per projection. Per replaced layer, gigabytes of stored expert weights are approximated with under a megabyte of seeds. This addresses the dual memory bottleneck of autoregressive Sparse MoE decode, where per-expert FFN operations are HBM-bandwidth-bound at small routed-token counts and the aggregate expert footprint forces multi-node Expert Parallelism (EP) with all-to-all traffic. We realize the approach as the Rotor Generation Unit (RGU), a fixed-function datapath that generates FFN weight tiles without competing with Tensor Core execution. With 30% of the MoE FFN layers replaced across five Sparse MoE models, we estimate 1.3-2.8x higher system throughput at matched GPU count and 1.10-1.15x lower per-user decode latency at short context. In exchange, downstream accuracy on three model families falls below that of the same model fine-tuned without rotor replacement, and the replacement ratio controls this tradeoff. FORGE also expands KV cache capacity by 1.2-2.6x. It is agnostic to the bit width at which weights are stored, so it can compose with quantization. The RGU is fully implemented/verified in SystemVerilog at ~0.9% SM area overhead (0.032 mm^2/SM, 7nm).
Figures & tables
Figure 1. FORGE replaces HBM-resident expert weights with on-chip procedural regeneration. (Top) Training adds an offline rotor-fitting step that compresses each dense expert into a rotor-parameter seed θ . (Bottom) At inference, the RGU inside each SM materializes weight tiles on-the-fly from seeds alone, reclaiming HBM capacity for an expanded KV cache.
Model
E
K
MoE%
Seed/layer
Comp.
DeepSeek-v3.2
256
8
94.5
594 KB
19,065×
GLM-5
256
8
98.2
509 KB
19,065×
Qwen3-235B
128
8
96.6
276 KB
8,738×
Qwen3-30B
128
8
95.0
221 KB
2,731×
Qwen3-Coder-Next
512
10
98.0
776 KB
2,081×
Table 1. Target Sparse MoE model configurations. E , K : total and activated experts; Seed: the FORGE parameters that replace one layer’s experts.
Table 5. Full-Model Decode Latency Speedup (FP8, RGU, B=1 , r=0.3 ). Baseline: TP+EP with minimum GPUs to fit weights. FORGE replaces 30% of the MoE layers; kept baseline MoE layers still pay EP all-to-all.
Figure 10. Context-length ablation (matched GPU count). (a) Decode speedup narrows as KV cache access dilutes the MoE FFN contribution. (b) Freed HBM grows max concurrent users per GPU sharply at long context. (c) The user-count gain offsets the narrowing decode speedup, so TPS gains hold or widen.
Figure 11. System throughput scaling across replacement ratios (r) (T=4096). Accuracy is evaluated at r=0.3 only; r=0.7 is a what-if point (Section 5.5 ).
Component
Value
Notes
Logic Area
0.017 mm2
PE array ∼ 69%
SRAM Area
0.015 mm2
28.875 KB, 4-bank
Total / SM
0.032 mm2
vs one SM (3.475 mm2 ( Locuza, 2022 ) )
∼ 0.9%
Clock (ASAP7)
1.80 GHz
WNS −65 ps @ 2 GHz
Logic Power (0.7 V)
35.9 mW
3.4 switch + 32.5 internal
Table 6. 7 nm PPA Summary for the FP8 dual-pair RGU.
Config
WikiText ↓
ARC-C ↑
HellaSwag ↑
ERNIE-21B
Baseline
8.37
58.00
61.10
Baseline + LoRA
5.93
58.96
62.50
FORGE
7.16
57.25
59.30
Qwen3-30B
Baseline
9.40
52.60
59.50
Table 7. Model performance with r=0.3 on ERNIE-21B , Qwen3-30B , and Qwen3-Coder-Next on WikiText, ARC-C, and HellaSwag. Baseline + LoRA is the reference for FORGE. The gap between the two is the accuracy cost of rotor replacement.