如何获得性能以在程序中查找符号 [英] How can I get perf to find symbols in my program

问题描述

使用perf report时，我的程序没有看到任何符号，而是得到如下输出:

When using perf report, I don't see any symbols for my program, instead I get output like this:

$ perf record /path/to/racket ints.rkt 10000
$ perf report --stdio

# Overhead   Command      Shared Object  Symbol
# ........  ........  .................  ......
#
    70.06%  ints.rkt  [unknown]          [.] 0x5f99b8        
    26.28%  ints.rkt  [kernel.kallsyms]  [k] 0xffffffff8103d0ca
     3.66%  ints.rkt  perf-32046.map     [.] 0x7f1d9be46650  

这是毫无根据的.

相关程序是用调试符号构建的，sysprof工具显示了适当的符号，Zoom也是如此，我认为它是在引擎盖下使用perf的.

The relevant program is built with debugging symbols, and the sysprof tool shows the appropriate symbols, as does Zoom, which I think is using perf under the hood.

请注意，这是在x86-64上，因此二进制文件是使用-fomit-frame-pointer编译的，但是在其他工具下运行时也是如此.

Note that this is on x86-64, so the binary is compiled with -fomit-frame-pointer, but that's the case when running under the other tools as well.

推荐答案

此帖子已有一年多的历史了，但是由于遇到相同问题时它出现在我的Google搜索结果的顶部，所以我认为d在这里回答.经过一番搜索之后，我发现了这个相关StackOverflow问题中的答案非常有帮助.然后，在我的Ubuntu Raring系统上，我完成了以下操作:

This post is already over a year old, but since it came out at the top of my Google search results when I had the same problem, I thought I'd answer it here. After some more searching around, I found the answer given in this related StackOverflow question very helpful. On my Ubuntu Raring system, I then ended up doing the following:

1. 用-g编译我的C ++源代码(显然，您需要调试符号)

2. 以

   运行perf

1. Compile my C++ sources with -g (fairly obvious, you need debug symbols)

2. Run perf as

record -g dwarf -F 97 /path/to/my/program

通过这种方式perf能够处理 DWARF 2 调试格式，标准格式gcc在Linux上使用. -F 97参数将采样率降低到97 Hz.默认采样率对于我的系统来说显然太大，并导致出现以下消息:

This way perf is able to handle the DWARF 2 debug format, which is the standard format gcc uses on Linux. The -F 97 parameter reduces the sampling rate to 97 Hz. The default sampling rate was apparently too large for my system and resulted in messages like this:

Warning:
Processed 172390 events and lost 126 chunks!

Check IO/CPU overload!

和perf report之后的调用将因分段错误而失败.在降低采样率的情况下，一切正常.

and the perf report call afterwards would fail with a segmentation fault. With the reduced sampling rate everything worked out fine.

如果需要内核符号，则以root用户身份也可以提供帮助.

as root can help as well, if kernel symbols are required.

这篇关于如何获得性能以在程序中查找符号的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！