perf 和火焰图

环境 & 版本

• Linux 5.10.16.3-microsoft-standard-WSL2 x86_64 x86_64
• Ubuntu 20.04.2 LTS
• perf version 5.10.16.3

NOTE: 如果没有特别说明，以下perf命令都在root权限下执行

查询 & 罗列

列出Virtual Memory相关的static tracepoint

• perf list 'vmscan:*'
  

• `perf list ‘kmem:*’
  k

• perf stat -a sleep
  

tracepoint 使能

通过 debugfs 中的相应文件使能 tracepoint

root@sie-luc:~# find /sys/kernel/debug/tracing/events/ -type d| grep -E 'dma|gpu'
/sys/kernel/debug/tracing/events/dma_fence
/sys/kernel/debug/tracing/events/dma_fence/dma_fence_emit
/sys/kernel/debug/tracing/events/dma_fence/dma_fence_init
/sys/kernel/debug/tracing/events/dma_fence/dma_fence_destroy
/sys/kernel/debug/tracing/events/dma_fence/dma_fence_enable_signal
/sys/kernel/debug/tracing/events/dma_fence/dma_fence_signaled
/sys/kernel/debug/tracing/events/dma_fence/dma_fence_wait_start
/sys/kernel/debug/tracing/events/dma_fence/dma_fence_wait_end
root@sie-luc:~# cat /sys/kernel/debug/tracing/events/dma_fence/dma_fence_enable_signal/
cat: /sys/kernel/debug/tracing/events/dma_fence/dma_fence_enable_signal/: Is a directory
root@sie-luc:~# cat /sys/kernel/debug/tracing/events/dma_fence/dma_fence_enable_signal/
enable   filter   format   id       trigger
root@sie-luc:~# cat /sys/kernel/debug/tracing/events/dma_fence/dma_fence_enable_signal/enable
0

常用命令

• perf top -e cycles

• perf record -F 999 -p PID -g

  • 默认会在当前目录下生成 perf.data, 后面如果再执行之前的 perf.data 会自动重命名 perf.data.old

• perf script | /path/to/FlameGraph/stackcollapse-perf.pl | /path/to/FlameGraph/framegraph.pl > result.svg

  • 生成火焰图需要这个脚本工具 FlameGraph，而且如果想看到详细的调用栈需要编译跟踪对象为 Debug 版本

References

• FlameGraph