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In this article, we will explore the GNU profiling tool ‘gprof’. In this step, the gprof tool is run with the executable name and the above. What is gprof? Gprof is a profiling program which collects and arranges statistics on your programs. Write hate-mail to gnu (but don’t tell them I told you to). Table of Contents. 1. Introduction to Profiling · 2. Compiling a Program for Profiling · 3. Executing the Program · 4. gprof Command Summary · Output Options.

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At run-time, timing values are obtained by statistical sampling.

GPROF Tutorial – How to use Linux GNU GCC Profiling Tool

Support Us Support this blog by purchasing one of my ebooks. Mark Richter February 13, The amount of error is usually more than one sampling period. In very large projects, profiling can save your day by not only determining the parts in your program which are slower in execution than expected but also can help you find many other statistics through which many potential bugs can be spotted and sorted out.

In a large application like yours, By using this site, you agree to the Terms of Use and Privacy Policy. In some versions, such as BSD, profiling of shared libraries can be limited because of restrictions of the profil function, which may be implemented as library function or as system call. Lets try and understand the three steps listed above through a practical example. Also, I agree that recursion is not all that difficult.


This can suggest places where you might try to eliminate function calls that use a lot of time. Hi Cody, You raise a lot of valid points, but let me itemize my objections to gprof. Indeed, it can always get faster and that is the con and pro of higher level languages; on the one hand, you can get more done sooner but on the other hand the executable will be larger and the executable will not be as efficient or as fast.

That self time matters as opposed to inclusive time, which includes gun time. The same goes the other way around too. Antoha Bikineev October 30, From attaching to the program during execution where you need to investigateyou then have an idea well, often where the problem is in which case you can get closer to solving the problem.

Notify me of followup comments via e-mail. Kessler, and Marshall K. I think it is better to make bigger time discrete in functions. This file contains a couple of tables flat profile and call graph in addition to some other information. On a related note, you should also understand how to debug your C program using gdb. On the other hand, call graph focuses on each function like the functions through which a particular function was called, what all functions were called from within this particular function etc Gprkf this way one can get idea of the execution time spent in the sub-routines too.

GPROF Tutorial – How to use Linux GNU GCC Profiling Tool

Mark Richter February 28,5: Also, your program needs to have sufficient permissions for gmon. It used a hybrid of instrumentation and sampling [1] and was created as an extended version of the older “prof” tool.


The resulting data is not exact, rather a statistical approximation. Journey of a Data Packet in the Internet. Unlike grof, gprof is capable of limited call graph collecting and printing.

Gpror Dunlavey February 28,8: A Selection, Kathryn S. Cody February 28, From Wikipedia, the free encyclopedia. Vivek Kumar December 30,9: Just mentioning that because I see that complaint a lot.

Not to be confused with the perfect hash function generator gperf.

Table of Contents

In this first step, we need to make sure that the profiling is enabled when the compilation of the code is done. It is easy to use,clearly and instructive. The main thing I was getting at is gprof has its uses and to dismiss it entirely is not always helpful but then so would be dismissing your points — they are valid. I have followups enabled so if you respond maybe I can help more. Sampling is done by probing the target program’s program counter at regular intervals using operating system interrupts programmed via profil 2 or setitimer 2 syscalls.

I take it that no one knows why a -pg program just hangs at the end of execution? Alex, The reason ctrl-c prevents it from producing a gmon. Sameer March 11,1: That measuring time of functions is good enough as opposed to lines of code or even instructions.