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73 lines
2.7 KiB
Markdown
73 lines
2.7 KiB
Markdown
## eBPF 入门实践教程：
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## origin
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origin from:
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https://github.com/iovisor/bcc/blob/master/libbpf-tools/runqslower.bpf.c
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result:
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```
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$ sudo ecli/build/bin/Release/ecli run examples/bpftools/runqslower/package.json
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running and waiting for the ebpf events from perf event...
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time task prev_task delta_us pid prev_pid
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20:11:59 gnome-shell swapper/0 32 2202 0
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20:11:59 ecli swapper/3 23 3437 0
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20:11:59 rcu_sched swapper/1 1 14 0
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20:11:59 gnome-terminal- swapper/1 13 2714 0
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20:11:59 ecli swapper/3 2 3437 0
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20:11:59 kworker/3:3 swapper/3 3 215 0
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20:11:59 containerd swapper/1 8 1088 0
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20:11:59 ecli swapper/2 5 3437 0
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20:11:59 HangDetector swapper/3 6 854 0
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20:11:59 ecli swapper/2 60 3437 0
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20:11:59 rcu_sched swapper/1 26 14 0
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20:11:59 kworker/0:1 swapper/0 26 3414 0
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20:11:59 ecli swapper/2 6 3437 0
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```
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这段代码定义了一个 eBPF 程序，该程序用于跟踪进程在运行队列中的等待时间。它通过使用 tracepoint 和 perf event 输出来实现。
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程序首先定义了两个 BPF 内核映射：start 映射用于存储每个进程在被调度运行之前的时间戳，events 映射用于存储 perf 事件。
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然后，程序定义了一些帮助函数，用于跟踪每个进程的调度状态。 trace_enqueue 函数用于在进程被调度运行之前记录时间戳， handle_switch 函数用于处理进程切换，并计算进程在队列中等待的时间。
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接下来，程序定义了五个 tracepoint 程序，用于捕获不同的调度器事件。 sched_wakeup 和 sched_wakeup_new 程序用于捕获新进程被唤醒的事件， sched_switch 程序用于捕获进程切换事件， handle_sched_wakeup 和 handle_sched_wakeup_new 程序用于捕获 raw tracepoint 事件。这些 tracepoint 程序调用了前面定义的帮助函数来跟踪进程的调度状态。
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最后，程序将计算得到的等待时间输出到 perf 事件中，供用户空间工具进行捕获和分析。
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## Compile and Run
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Compile:
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```
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docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest
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```
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Or
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```console
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$ ecc exitsnoop.bpf.c exitsnoop.h
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Compiling bpf object...
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Generating export types...
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Packing ebpf object and config into package.json...
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```
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Run:
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```console
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$ sudo ./ecli run package.json
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TIME PID PPID EXIT_CODE DURATION_NS COMM
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21:40:09 42050 42049 0 0 which
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21:40:09 42049 3517 0 0 sh
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21:40:09 42052 42051 0 0 ps
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21:40:09 42051 3517 0 0 sh
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21:40:09 42055 42054 0 0 sed
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21:40:09 42056 42054 0 0 cat
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21:40:09 42057 42054 0 0 cat
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21:40:09 42058 42054 0 0 cat
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21:40:09 42059 42054 0 0 cat
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```
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