精确时间协议如何处理闰秒

We’ve previously described why we think it’s time to leave the leap second in the past. In today’s rapidly evolving digital landscape, introducing new leap seconds to account for the long-term slowdown of the Earth’s rotation is a risky practice that, frankly, does more harm than good. This is particularly true in the data center space, where new protocols like Precision Time Protocol (PTP) are allowing systems to be synchronized down to nanosecond precision.

我们之前已经描述了为什么我们认为是时候将闰秒留在过去。在当今快速发展的数字环境中，引入新的闰秒以应对地球自转的长期减速是一种风险做法，坦率地说，这弊大于利。这在数据中心领域尤其如此，新的协议如精确时间协议（PTP）允许系统精确到纳秒级别进行同步。

With the ever-growing demand for higher precision time distribution, and the larger role of PTP for time synchronization in data centers, we need to consider how to address leap seconds within systems that use PTP and are thus much more time sensitive.

随着对更高精度时间分配的需求不断增长，以及 PTP在数据中心时间同步中的更大作用，我们需要考虑如何在使用PTP的系统中处理闰秒，这些系统对时间的敏感性更高。

Leap second smearing – a solution past its time

闰秒平滑 - 一种过时的解决方案

Leap second smearing is a process of adjusting the speeds of clocks to accommodate the correction that has been a common method for handling leap seconds. At Meta, we’ve traditionally focused our smearing effort on NTP since it has been the de facto standard for time synchronization in data centers.

闰秒涂抹是调整时钟速度以适应修正的过程，这一直是处理闰秒的常见方法。在Meta，我们传统上将涂抹工作集中在NTP上，因为它一直是数据中心时间同步的事实标准。

In large NTP deployments, leap second smearing is generally performed at the Stratum 2 (layer), which consists of NTP servers that directly interact with NTP clients (the Stratum 3) that are the downstream users of the NTP service.

在大型NTP部署中，闰秒涂抹通常在Stratum 2（层）进行，该层由直接与NTP客户端（Stratum 3）交互的NTP服务器组成，后者是NTP服务的下游用户。

There are multiple approaches to smearing. In the case of NTP, linear or quadratic smearing formulas can be applied.

有多种平滑方法。在NTP的情况下，可以应用线性或二次平滑公式。

Quadratic smearing is often preferred due to the layered nature of the NTP protocol, where clients are encouraged to dynamically adjust their polling ...