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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You can also simply drop me a line gpof say hello!. Yes, I understand the limitations of most program analysis tools. 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.
Instrumentation code is automatically inserted into the program code during compilation for example, by using the ‘-pg’ option of the gcc compilerto gather caller-function data.
Antoha Bikineev October 30, Hopefully that clears up any points from my end you did indeed clear up your points and I — besides being surprised you responded to me responding from your response from — appreciate it. Sampling data is saved in ‘gmon. There is also an estimate of how much time was spent in the subroutines of each function. Why would the profiling version hang up at the end of program execution like that? I take it that no one knows why a -pg program just hangs at the end of execution?
Also, I agree that recursion is gpdof all that difficult. That recursion is a tricky confusing issue it only is a problem when trying to construct gnuu annotated call graph.
Note that I have used and will be using -b option so as to avoid extra information in analysis output. Retrieved from ” https: This never happens when the non-profiling version is run.
Gprof – Wikipedia
Mark Richter February 13, Some of them are discussed below:. 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.
Views Read Edit View history. Bugs listed are irrelevant as again, just because something has a problem does not mean it is useless or never useful in any way shape or form.
Well, I ran the proram again, and this time it produced the gmon. In the second step, the binary file produced as a result of step-1 above is executed so that profiling information can be generated. Thanks for this great article! As a quick addendum: If there are some static functions whose profiling information you do not require then this can be achieved using -a option:. Dario August 13,8: Several gmon files can be combined with ‘gprof -s’ to accumulate data from several runs of a program.
A call to the monitor function ‘mcount’ is inserted before each function call. Say for high performance applications.
Lets try and understand the three steps listed above through a gpprof example. You must use this option when compiling the source files you want data about, and you must also use it when linking.
GPROF Tutorial – How to use Linux GNU GCC Profiling Tool
Through profiling one can determine the parts in program code that are time consuming and need to be re-written. Mike Dunlavey February 14,6: In other words, in the hands of an experienced programmer, it is gnuu very valuable tool for exactly what you claim it isn’t good for. The individual columns for the flat profile as well as call graph are very well explained in the output itself. A Selection, Kathryn S. Mike Dunlavey February 28,7: The man page, by the way, suggests this: Mark Richter February 28,5: The same goes the other way around too.
You raise a lot of valid points, but let me itemize my objections to gprof.
GNU gprof – Table of Contents
That samples have to be taken at high frequency they do not. 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.
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. That accuracy of measurement is important vnu opposed to accuracy of identifying speedup opportunities.
I have followups enabled so if you respond maybe I can help more. It is easy to use,clearly and instructive.