通过硬件微架构调控,动态限制AI性能以增强系统安全。
Hardware Mechanisms to Dynamically Throttle AI Performance

- 利用缓存大小、延迟、带宽等微架构参数实现动态性能调控。
- 资源降至1/8时性能下降最高达80%,且响应仅需5-80K周期。
- 成本极低(<10K触发器),适合部署在现有GPU架构中。
随着更强大的AI模型被集成到关键计算机系统中,缺乏对AI意图的控制催生了安全机制的需求。现有软件防护仅施加行为约束,可能被足够智能的模型绕过。虽然硬件级安全被视为最后防线,但目前仅有访问策略或粗粒度全芯片关机等机制。本文提出一套可在运行时动态调控可用硬件资源的微架构控制旋钮,评估了涵盖GPU内存子系统的容量、带宽、延迟和频率维度的候选方案,最终确定四个强候选:L2缓存大小、L2延迟、L2带宽及共享内存端口访问速率。所有机制均基于成熟微架构原语构建:缓存道屏蔽、基于信用的速率限制、延迟插入与银行仲裁。实验表明,这些旋钮可实现高达80%的性能敏感度(资源为1/8时),实现成本极低(<~10K触发器),动态调节后稳定时间仅5-80K周期,对芯片其他部分影响微乎其微。多旋钮联合分析显示,组合使用可产生叠加效应,进一步扩大性能调控范围。
原文摘要 · Abstract (English)
As more capable AI models are increasingly integrated into critical computer systems, the lack of control over AI intent motivates safety mechanisms. Existing software safeguards impose only behavioral constraints that can potentially be bypassed by sufficiently intelligent models. While hardware-level safety enforcement has been recognized as an essential last line of defense, few mechanisms have been proposed beyond policy regulations on unauthorized accesses or coarse full-chip shutdown. What is missing is a fine-grained, dynamic intervention mechanism at the architecture level. In this paper, we introduce a set of microarchitecture knobs which dynamically control the available hardware resources to limit AI performance at runtime. We evaluate candidate knobs spanning the GPU memory subsystem, across capacity, bandwidth, latency and frequency dimensions, and narrow down to four strong candidates: L2 size, L2 latency, L2 bandwidth, and shared memory port access rate. To minimize new logic and extra design cost, we build all four mechanisms from well-established microarchitectural primitives: cache way masking, credit-based rate limiting, latency insertion, and bank arbitration. We show that these knobs achieve high performance sensitivity (up to 80% performance cut at 1/8 resource availability), negligible implementation cost (<~10K flip flops), fast stabilization after dynamic throttling (5-80K cycles), and minimal collateral impact on the rest of the chip. Further, multi-knob analysis reveals combinations of knobs that amplify the performance degradation beyond the effect of each knob individually, which enables a broader range of performance targets.
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