gprof produces empty output

2019-04-18 03:13发布

I'm running Ubuntu 16.10 and trying to profile a program using gprof. I compile with the flag -pg and the program is single-threaded. The actual compile commands are:

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

The program takes a couple of seconds to finish when I run it, and a file named gmon.out is produced. However, when I run gprof ./build/test/performance/stencil_application, the output I get contains no numbers. I only get the table headings and the explanation for the different fields, like this:

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.

and so on.

I've also tried to compile without -O3 and with -g, but with the same result. Does anybody know what's wrong?

1条回答
我只想做你的唯一
2楼-- · 2019-04-18 03:50

As pointed out in the comment by Tony Beta Lambda above, this is a bug in gcc. There are two possible workarounds: Downgrade to gcc-4.9, or compile with the flag -no-pie.

查看更多
登录 后发表回答