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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My focus is to write articles that will either teach you or help you resolve a problem. The human eye can recognize similarities between state samples stack and data that no summarizing backend of any profiler has any hope of exposing to the user. Anonymous March 21,4: 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.
As you would have already seen that gprof produces output with lot of verbose information so in case this information is not required then this can be achieved using the -b flag.
You can think the software is as fast as possible, when in fact it could be much faster. Ehsan March 16,7: GPROF output consists gprfo two parts: This helps make your program execution faster which is always desired.
While flat profile gives an overview of gprf timing information of the functions like time consumption for the execution of a particular function, how many times it was called etc. On a related note, you should also understand how to debug your C program using gdb. Could you please add details about how to get gmon. It produced the gmon. Hi Mike, Well your points are also valid.
Thank you very much, keep up the good work! Also, g;rof it is desired to suppress a specific function from call graph then this can be achieved by passing the desired function name along with the -Q option to the gprof tool. In other words, in the gpdof of an experienced programmer, it is a very valuable tool for exactly what you claim it isn’t good for.
Note that I have used and will be using -b option so as to avoid extra information in analysis output. Cody February 28, Kessler, and Marshall K. The resulting data is not exact, rather a statistical approximation. gju
GPROF Tutorial – How to use Linux GNU GCC Profiling Tool
But because difference in g;rof is small, every time program executes we can get different sort results in flat profile. Now lets see the analysis output:.
Will B Gprpf 2,1: It is easy to use,clearly and instructive. There are various flags available to customize the output of the gprof tool. There is also an estimate of how much time was spent in the subroutines of each function.
Table of Contents
The reason ctrl-c prevents it from producing a gmon. The mcount function may not be thread-safe in some implementations, so multi-threaded application profiles can be incorrect typically it only profiles the main thread of application. I have been using gprof to isolate a performance issue in a large scale business application, but recent attempts to do this have stalled.
Lets try and understand the three steps listed above through a practical example. You can also simply drop me a line to say hello!.
Gprof – Wikipedia
This produces an analysis file which contains all the desired profiling information. Also, I agree that recursion is not all that difficult. 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 So this way one can get idea of the execution time spent in the sub-routines too. Well your points are also valid.
Gprog take it that no one knows why a -pg program just hangs at the end of execution? Thanks and it is very simple. The flat profile is mainly about self time, which in a large program is usually irrelevant because the real problems are mid-stack. I think it is better to make bigger time discrete in functions.
In this first step, we need to make sure that the profiling is enabled when the compilation of the code is done. Journey of a Data Packet in the Internet. Also, if there is a requirement to print flat profile but excluding a particular function then this is also possible using -P flag by passing the function name to exclude along with it. Gprof is a performance analysis tool for Unix applications. Ynu 3rd from last paragraph: The last step above produces an analysis file which is in human readable form.
Yes, I understand the limitations of most program analysis tools. Bugs listed are irrelevant as again, just because something has a problem does ggprof mean it is useless or never useful in any way shape or form. Through profiling one can determine the parts in program code that are time consuming and need to be re-written. GPROF is not very good for what you need.