Sustainable Computing: Informatics and Systems the Need for Speed and Stability in Data Center Power Capping
Sustainable Computing: Informatics and Systems the Need for Speed and Stability in Data Center Power Capping
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可持续计算：信息学和系统数据中心功率上限对速度和稳定性的需求
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通讯作者：
S. Sankar
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作者：
A. Bhattacharya;D. Culler;A. Kansal;Sriram Govindan;S. Sankar
数据中心可以通过为实际峰值功耗而不是服务器铭牌额定功率提供昂贵的电气设备（如UPS，柴油发电机和冷却能力）来显著降低成本。但是，由于软件行为，在极少数情况下可能会超过此供应不足的功率水平，并可能导致整个数据中心基础设施违反安全限制。需要一种机制来限制服务器以保持在规定的预算内，并且基于处理器频率缩放的功率封顶方法可容易地用于此目的。我们表明，现有的方法，当应用于大量的服务器，是不够快，在数据中心观察到的快速电源动态下正确运行。我们还表明，现有的方法，当应用到一个开放的系统（其中的需求是独立的服务率）可能会导致级联故障的软件服务托管，导致服务性能下降无法控制，即使功率封顶应用于只有一个小的功耗降低。我们讨论了这些缺点的原因，并指出技术，可以产生一个安全，快速，稳定的功率封顶解决方案。我们的技术使用准入控制，以限制功耗，并确保稳定性，从而在数量级的性能提高。我们还讨论了为什么准入控制不能取代现有的功率封顶方法，但必须与它们相结合。
Data centers can lower costs significantly by provisioning expensive electrical equipment (such as UPS, diesel generators, and cooling capacity) for the actual peak power consumption rather than server name-plate power ratings. However, it is possible that this under-provisioned power level is exceeded due to software behaviors on rare occasions and could cause the entire data center infrastructure to breach the safety limits. A mechanism to cap servers to stay within the provisioned budget is needed, and processor frequency scaling based power capping methods are readily available for this purpose. We show that existing methods, when applied across a large number of servers, are not fast enough to operate correctly under rapid power dynamics observed in data centers. We also show that existing methods when applied to an open system (where demand is independent of service rate) can cause cascading failures in the software service hosted, causing the service performance to fall uncontrollably even when power capping is applied for only a small reduction in power consumption. We discuss the causes for both these shortcomings and point out techniques that can yield a safe, fast, and stable power capping solution. Our techniques use admission control to limit power consumption and ensure stability, resulting in orders of magnitude improvement in performance. We also discuss why admission control cannot replace existing power capping methods but must be combined with them.