问题
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?
回答1:
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.
来源：https://stackoverflow.com/questions/42620074/gprof-produces-empty-output