Facebook开发新的开源计时设备，仅需一个PCIe插槽即可工作

{"type":"doc","content":[{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"2021年8月11日，Facebook 分享了其Time cards 硬件和软件设计。"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"2021年8月11日，Facebook工程师分享他们已经构建了一个用于网络同步的时间设备Time cards并开源了整个规范，该设备基于超精确原子钟和导航卫星的计时技术，将有助于在大规模互联网上加速服务。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"每一台数字设备都需要知道现在是什么时间，有了时间这个维度，设备才能正确提供各种服务并记录各种类型的日志。尤其对于 Facebook 这种拥有几十亿用户规模的社交网络而言，没有精确的时间就无法协调数据中心的工作，因此 Facebook 决定打造自己的计时设备。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"NTP和Stratum One各有不足"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"在Time cards被分享之前，基本上有两种方法来检查时间。开发者会使用NTP（Network TimeProtocol，网络时间协议）作为时间检查机制，但是这种公共 NTP 池增加了对互联网连接的依赖，并可能影响系统的整体安全性和可靠性。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"运行封闭式数据中心的公司会由一个叫Stratum One的硬件设备来充当时间保持者。但它们是由少数几家公司多年来建造的，所以很难获得新的功能，并且因为它们具有专利性质，所以像Facebook这样的公司无法控制这些盒子。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"新的Time cards更准确、更便宜"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"Time Cards 本质上是使用与插入图形卡和其他设备相同的 PCI Express 扩展卡技术安装到服务器中的电子板。Facebook 把插有 Time Card 并运行其计时软件的服务器称为时间设备。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"Time Card 通过监听嵌入在 GNSS 导航卫星无线电信号中的计时信息而保持同步。时间卡潜伏在数据中心的深处，但它们连接到屋顶安装的天线，以接收卫星信号。之后，包括微型原子钟在内的一套电子元件会处理获得的数据，以供数据中心服务器使用。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"目前，Time Card 的规格、原理图、材料清单（BoM）和源代码等都已托管至GitHub仓库。如果普通开发者不需要 Facebook 那么高的时间精度水平，可以通过换上更传统的晶体振荡器使成本降至约 300 美元。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"Facebook工程师表示：希望通过开源工作来帮助更多人"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"Facebook 表示，打造一款非常精确、价格低廉且不受供应商限制的设备本身就是一项成就。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"他们在早期就决定将设计过程开源，以便其他公司和工程师能够为设计做出贡献。此举显示了互联网大部分公司的合作精神。即使像 Facebook、微软和谷歌这样的公司之间会有激烈竞争，他们也会为可以使竞争对手受益的开源项目做出贡献。这方面，最好的例子是全球范围内规模最大的开源软件项目Linux，它是 Android 手机、SpaceX 航天器、超级计算机和无数数据中心服务器操作系统的基础。可以说开源使全球信息技术领域发生了全局性、持续性的重大变化，在社会基础设施建设方面也发挥着越来越重要的作用。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":" "}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}],"text":"参考链接："},{"type":"link","attrs":{"href":"https:\/\/engineering.fb.com\/2021\/08\/11\/open-source\/time-appliance\/","title":null,"type":null},"content":[{"type":"text","text":"https:\/\/engineering.fb.com\/2021\/08\/11\/open-source\/time-appliance\/"}],"marks":[{"type":"color","attrs":{"color":"#494949","name":"user"}}]}]}]}