2017-03-06 117 views
14

我正在运行Ubuntu 16.10并尝试使用gprof来分析程序。我编译的标志是-pg,程序是单线程的。实际的编译命令是:gprof产生空输出

g++ -I. -std=c++11 -Wall -Wextra -O3 -pg -fPIC -Wno-unused-parameter -c -o build/obj/performance/stencil_application.o test/performance/stencil_application.cpp 
g++ -I. -std=c++11 -Wall -Wextra -O3 -pg -Wno-unused-parameter build/obj/performance/stencil_application.o -o build/test/performance/stencil_application 

该方案需要几秒钟,当我运行它来完成,并命名文件是gmon.out产生。但是,当我运行gprof ./build/test/performance/stencil_application时,我得到的输出不包含数字。我只收到表格标题和不同字段的解释,如下所示:

Flat profile: 

Each sample counts as 0.01 seconds. 
    % cumulative self    self  total   
time seconds seconds calls Ts/call Ts/call name  

%   the percentage of the total running time of the 
time  program used by this function. 

cumulative a running sum of the number of seconds accounted 
seconds for by this function and those listed above it. 

self  the number of seconds accounted for by this 
seconds function alone. This is the major sort for this 
      listing. 

calls  the number of times this function was invoked, if 
      this function is profiled, else blank. 

self  the average number of milliseconds spent in this 
ms/call function per call, if this function is profiled, 
      else blank. 

total  the average number of milliseconds spent in this 
ms/call function and its descendents per call, if this 
      function is profiled, else blank. 

name  the name of the function. This is the minor sort 
      for this listing. The index shows the location of 
      the function in the gprof listing. If the index is 
      in parenthesis it shows where it would appear in 
      the gprof listing if it were to be printed. 

Copyright (C) 2012-2016 Free Software Foundation, Inc. 

Copying and distribution of this file, with or without modification, 
are permitted in any medium without royalty provided the copyright 
notice and this notice are preserved. 

        Call graph (explanation follows) 


granularity: each sample hit covers 2 byte(s) no time propagated 

index % time self children called  name 

This table describes the call tree of the program, and was sorted by 
the total amount of time spent in each function and its children. 

等等。

我也尝试编译没有-O3-g,但结果相同。有人知道什么是错的吗?

+6

听起来像[这个bug](https://bugs.launchpad.net/ubuntu/+source/gcc-6/+bug/1678510) –

+0

我有同样的问题。 – thb

+0

@thb:查看上面的评论 – Malin

回答

10

正如上面的Tony Beta Lambda在评论中指出的那样,这是一个bug in gcc。有两种可能的解决方法:降级到gcc-4.9,或使用标记--no-pie进行编译。

+0

它适用于GCC 6.3。同时使用--no-pie和-pg。 –

+3

对我来说,'-no-pie'(注意单个破折号)起作用,而'--no-pie'没有。 – 7anner

+0

正确的标志确实是'-no-pie'。 – Olivier