使用 Linux Perf
¥Using Linux Perf
Linux Perf 使用 JavaScript、原生和操作系统级框架提供底层 CPU 分析。
¥Linux Perf provides low level CPU profiling with JavaScript, native and OS level frames.
重要：本教程仅适用于 Linux。
¥Important: this tutorial is only available on Linux.
如何
¥How To
Linux Perf 通常可通过 linux-tools-common 包获得。通过 --perf-basic-prof 或 --perf-basic-prof-only-functions，我们可以启动支持 perf_events 的 Node.js 应用。
¥Linux Perf is usually available through the linux-tools-common package. Through either --perf-basic-prof or
--perf-basic-prof-only-functions we are able to start a Node.js application supporting perf_events.
--perf-basic-prof 将始终写入文件 (/tmp/perf-PID.map)，这可能导致磁盘无限增长。如果担心这一点，请使用模块：linux-perf 或 --perf-basic-prof-only-functions。
¥--perf-basic-prof will always write to a file (/tmp/perf-PID.map), which can lead to infinite disk growth.
If that’s a concern either use the module: linux-perf
or --perf-basic-prof-only-functions.
两者之间的主要区别在于 --perf-basic-prof-only-functions 产生的输出较少，它是生产分析的可行选择。
¥The main difference between both is that --perf-basic-prof-only-functions produces less output, it is a viable option
for production profiling.
# Launch the application an get the PID
$ node --perf-basic-prof-only-functions index.js &
[1] 3870
然后根据所需频率记录事件：
¥Then record events based in the desired frequency:
$ sudo perf record -F 99 -p 3870 -g
在此阶段，你可能希望在应用中使用负载测试，以便生成更多记录以进行可靠的分析。当作业完成后，通过向命令发送 SIGINT（Ctrl-C）来关闭 perf 进程。
¥In this phase, you may want to use a load test in the application in order to generate more records for a reliable analysis. When the job is done, close the perf process by sending a SIGINT (Ctrl-C) to the command.
perf 将在 /tmp 文件夹中生成一个文件，通常称为 /tmp/perf-PID.map（在上面的示例中为：/tmp/perf-3870.map），其中包含每个调用函数的跟踪。
¥The perf will generate a file inside the /tmp folder, usually called /tmp/perf-PID.map
(in above example: /tmp/perf-3870.map) containing the traces for each function called.
要将这些结果汇总到特定文件中，请执行：
¥To aggregate those results in a specific file execute:
$ sudo perf script > perfs.out
原始输出可能有点难以理解，因此通常使用原始文件来生成火焰图以获得更好的可视化效果。
¥The raw output can be a bit hard to understand so typically the raw file is used to generate flamegraphs for a better visualization.
要从此结果生成火焰图，请按照步骤 6 中的 本教程 进行操作。
¥To generate a flamegraph from this result, follow this tutorial from step 6.
由于 perf 输出不是 Node.js 专用工具，因此它可能与 Node.js 中 JavaScript 代码的优化方式存在问题。有关进一步参考，请参阅 perf 输出问题。
¥Because perf output is not a Node.js specific tool, it might have issues with how JavaScript code is optimized in
Node.js. See perf output issues for a
further reference.
有用的链接
¥Useful Links