如何使用性能跟踪记录？

我可以perf trace用作 的低开销替代品strace，例如跟踪所有 Apache 实例：

perf trace -p $(pidof apache2 | tr ' ' ',')

只运行最多 10 秒的跟踪：

perf trace -p $(pidof apache2 | tr ' ' ',') -- sleep 10

一些示例输出：

server ~ # perf trace -p $(pidof apache2 | tr ' ' ',') -- sleep 10 2>&1 | head
         ? (         ): apache2/8661  ... [continued]: poll()) = 0 Timeout
     0.022 ( 0.005 ms): apache2/8661 close(fd: 28                                                          ) = 0
     0.066 ( 0.007 ms): apache2/8661 read(fd: 13<pipe:[3452760950]>, buf: 0x7ffe815038ff, count: 1         ) = -1 EAGAIN Resource temporarily unavailable
         ? (         ): apache2/26492  ... [continued]: semop()) = 0
     0.088 (         ): apache2/8661 semop(semid: 557481986, tsops: 0x7f846e0cfd6c, nsops: 1               ) ...
         ? (         ): apache2/7580  ... [continued]: epoll_wait()) = 1
    46.136 (         ): apache2/26492 epoll_wait(epfd: 27<anon_inode:[eventpoll]>, events: 0x7f846dd0c698, maxevents: 5, timeout: 10000) ...
    46.081 ( 0.013 ms): apache2/7580 accept4(fd: 12<socket:[3452759675]>, upeer_sockaddr: 0x7ffe81503830, upeer_addrlen: 0x7ffe81503810, flags: 524288) = 28
    46.100 ( 0.010 ms): apache2/7580 semop(semid: 557481986, tsops: 0x7f846e0cfd60, nsops: 1               ) = 0
    46.116 ( 0.002 ms): apache2/7580 getsockname(fd: 28<socket:[3465711918]>, usockaddr: 0x7f846dd0a130, usockaddr_len: 0x7f846dd0a110) = 0

这按预期工作。现在我想将这些事件记录在一个文件中，以便以后详细分析它们。我曾预料perf trace record会这样做，但我什至不确定这是否正确记录：

server ~ # perf trace record -p $(pidof apache2 | tr ' ' ',') -- sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0,312 MB perf.data (67 samples) ]

perf trace ... | wc -l总计约 12000 行，那么为什么record只记录 67 个样本？

我什至不确定读取此文件的正确命令是什么；不幸的是，手册页没有说。我假设它是perf trace -i perf.data，但这不会打印任何东西：

server ~ # perf trace -i perf.data
server ~ # 

perf script确实打印了一些东西，但它看起来不像perf trace输出：

server ~ # perf script | head
         apache2 10215 [002] 29556325.787512:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2 20085 [006] 29556325.787597:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2 20754 [000] 29556325.790512:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2  7580 [007] 29556325.790757:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2  8661 [001] 29556325.796044:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2 10215 [006] 29556325.796845:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2 20085 [004] 29556325.798481:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2 10215 [004] 29556325.802922:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2 20754 [001] 29556325.815999:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])
         apache2 20085 [003] 29556325.816025:          1 cycles:ppp:  ffffffff83e5a704 native_write_msr+0x4 ([kernel.kallsyms])