How to Measure the Killer Microsecond
How to Measure the Killer Microsecond
复制标题
如何测量杀手微秒
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
K. Argyraki
中科院分区：
文献类型：
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作者：
Mia Primorac;Edouard Bugnion;K. Argyraki
数据中心网络研究需要工具来生成流量并准确测量延迟和吞吐量。虽然基于硬件的工具在商业上已经存在很长时间，但它们主要用于验证ASIC并且缺乏灵活性，例如，研究新的协议对学者来说也太贵了。最近开发的内核旁路网络和高级NIC功能（如硬件时间戳）为精确的延迟测量创造了新的机会。本文比较了这两种方法，特别是商品服务器和网络服务器，当正确配置时，是否可以像专用硬件一样精确地测量延迟分布。我们的工作表明，设计良好的商品解决方案可以捕获无状态UDP流量尾部延迟的细微差异。我们使用硬件设备作为基础事实，以测量延迟和转发流量。我们将地面实况与结合了联合收割机的五个延迟测量客户端和五个不同端口转发解决方案和配置的观察结果进行比较。最先进的软件，如MoonGen，使用NIC硬件时间戳，提供了足够的可见性，以研究微妙的操作系统配置更改的影响。我们还观察到，基于内核旁路的TRex软件仅依赖于CPU来标记流量，当NIC时间戳对于特定协议或设备不可用时，也可以提供可靠的结果。
Datacenter-networking research requires tools to both generate traffic and accurately measure latency and throughput. While hardware-based tools have long existed commercially, they are primarily used to validate ASICs and lack flexibility, e.g., to study new protocols. They are also too expensive for academics. The recent development of kernel-bypass networking and advanced NIC features such as hardware timestamping have created new opportunities for accurate latency measurements. This paper compares these two approaches, and in particular whether commodity servers and NICs, when properly configured, can measure the latency distributions as precisely as specialized hardware. Our work shows that well-designed commodity solutions can capture subtle differences in the tail latency of stateless UDP traffic. We use hardware devices as the ground truth, both to measure latency and to forward traffic. We compare the ground truth with observations that combine five latency-measuring clients and five different port forwarding solutions and configurations. State-of-the-art software such as MoonGen that uses NIC hardware timestamping provides sufficient visibility into tail latencies to study the effect of subtle operating system configuration changes. We also observe that the kernel-bypass-based TRex software, that only relies on the CPU to timestamp traffic, can also provide solid results when NIC timestamps are not available for a particular protocol or device.