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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Sampling data is saved in ‘gmon.
Gprof – Wikipedia
The man page, by the way, suggests this: If you simply want to know which functions burn most of the cycles, it is stated concisely here. As usual in life, it gpfof a matter of using the tool in the right way in addition to using the right tool and that involves having enough experience in order to interpret it you know, sort of like you don’t use a hammer to put a screw gproof a screw hole? Thanks and it is very simple.
Several gmon files can be combined with ‘gprof -s’ to accumulate data from several runs of a program.
Table of Contents
Superb one keep up the good work man…. Output is sorted by percentage, with hot spots at the top of the list. Cody February 28, This can suggest places where you might try to eliminate function calls that use a lot of time.
Gprof is a performance analysis tool for Unix applications. Hi Mike, Well your points are also valid. Mutual recursion and non-trivial cycles are not resolvable by gptof gprof approach context-insensitive call graphbecause it only records arc traversal, not full call chains.
In this first step, we need to make sure that the profiling is enabled when the compilation of the code is done.
GPROF Tutorial – How to use Linux GNU GCC Profiling Tool
There is also an estimate of how much time was spent in the subroutines of each function. On a related note, you should also understand how to debug your C program using gdb.
Webarchive template wayback links. There were analogous utility in glibc called ‘sprof’ to profile dynamic libraries. That invocation counting is useful as opposed to getting inclusive time percent. Say for high performance applications. Responding to your revised third paragraph: The second part of the output is the textual call graph, which shows for each function who called it parent and who it called child subroutines.
You raise a lot of valid points, but let me itemize my objections to gprof.
In flat profile we expect that func1 works longer than func2. You must use this option when compiling the source files you want data about, and you must also use it when linking. I think point 10 is exactly what I was getting at: Now lets see the analysis output:.
I have been using gprof to isolate a performance issue in a large scale business application, but recent attempts to do this have stalled. Well your points are also valid. Use this Contact Form to get in touch me with your comments, questions or suggestions about this site.
The man page, by the way, suggests this:. I have followups enabled so if you respond maybe I can help more.
Some of them are discussed below:. The reason ctrl-c prevents it from producing a gmon. It is easy to use,clearly and instructive. Support Us Support this blog by purchasing one of my ebooks. ggprof
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. 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. If a value is n times the sampling period, the expected error in the value is the square root of n sampling periods.
My only comment here is that what we did get from the few profiling runs that ran to completion helped us identify exactly what the performance problems were. Anyway, as for why it would hang, a question and a suggestion on figuring out where its having issues: