我正在运行Ubuntu 16.10，并尝试使用gprof对一个程序进行性能分析。我使用-pg标志进行编译，该程序是单线程的。实际的编译命令如下：
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
当我运行该程序时，它需要几秒钟才能完成，并生成一个名为gmon.out的文件。但是，当我运行 gprof ./build/test/performance/stencil_application 时，输出结果中不包含任何数字。我只得到表头和各个字段的解释，如下：
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.
等等就是这样。
我也尝试过不带-O3和带-g进行编译，但结果相同。有人知道是什么问题吗？