用激励机制让分布式矿工协作训练大模型,突破单机显存限制。
Incentivised Orchestrated Training Architecture (IOTA): A Technical Primer for Release
- 将矿工分层并流式传输激活值,实现模型规模随参与人数无限扩展。
- 激活值压缩最高达128倍,结合蝴蝶形全归约提升训练速度与可扩展性。
- 按贡献精细分配奖励,防止模型囤积,适合去中心化训练研究者参考。
2024年8月,Bittensor的Subnet 9(SN9)证明了基于区块链的去中心化预训练是可行的,其分布式网络中的无许可参与者各自训练了参数量在7亿至140亿之间的大语言模型,并超越了现有基线。但该方案存在两大核心问题:(i) 每个矿工需本地存储完整模型;(ii) “赢家通吃”奖励机制导致模型囤积。本文提出IOTA(Incentivized Orchestrated Training Architecture),通过将原本孤立的矿工整合为协同工作的统一单元,解决了上述限制,实现任意规模扩展并公平激励。关键成果包括:(1) 数据与流水线并行的SWARM架构——协调器将模型层分发至异构矿工,并流式传输激活值,使模型规模可随参与节点数增长,不再受限于单机显存;(2) 细粒度连续激励——验证者量化各矿工贡献,按比例分配代币发行;(3) 激活值压缩——利用模型瓶颈将激活通信带宽降低至原值的1/128,显著提升训练效率;(4) Butterfly All-Reduce——矿工以O(1)带宽完成不重叠参数片的平均,实现线性可扩展性、冗余与内置合谋检测;(5) CLASP(路径采样贡献损失评估)——一种公平归因机制,根据边际效用分配信用,即使贡献相互依赖仍能识别异常行为。
原文摘要 · Abstract (English)
In August 2024, Bittensor's Subnet 9 (SN9) demonstrated that a distributed network of incentivized, permissionless actors could each pretrain large language models (LLMs) ranging from 700 million to 14 billion parameters, while surpassing established baselines. While that work validated blockchain-based decentralized pretraining as viable, it contained core issues: (i) every miner had to fit an entire model locally, and (ii) "winner-takes-all" rewards encouraged model hoarding. Here we introduce IOTA (Incentivized Orchestrated Training Architecture), an architecture that addresses these limitations by transforming SN9's previously isolated competitors into a single cooperating unit that can scale arbitrarily while still rewarding each contributor fairly. Key preliminary results: (1) Data- and Pipeline-parallel SWARM architecture - An orchestrator distributes model layers across heterogeneous miners and streams activations between them, enabling model sizes to scale with the number of participants rather than being constrained by the VRAM of a single machine; (2) Granular, continuous incentives - Validators measure each miner's contribution and allocate token emissions proportionally; (3) Activation compression - We used model-bottlenecks to cut communication bandwidths of activations by up to 128x, vastly improving training speed; (4) Butterfly All-Reduce - Miners average disjoint parameter slices in O(1) bandwidth, offering linear scalability, redundancy and built-in collusion detection; (5) CLASP (Contribution Loss Assessment via Sampling of Pathways) - A fair attribution scheme assigns credit to miners proportional to their marginal utility and detects exploits, even when contributions are interdependent across the pipeline.
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