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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Gprof – Wikipedia
In other words, in the hands of an experienced programmer, it is a very valuable tool for exactly what you claim it isn’t good for. Mike Dunlavey February 28,8: Retrieved from ” https: I could go into greater ghu on any of these if necessary.
That accuracy of measurement is important as opposed to accuracy of identifying speedup opportunities. Sampling data is saved in ‘gmon.
GPROF Tutorial – How to use Linux GNU GCC Profiling Tool
Mike Dunlavey October 2,1: Cody February 28, So we see that a flat profile containing information related to only function func1 is displayed. In some versions, such as BSD, profiling of shared libraries can be limited gprod of restrictions of the gpgof function, which may be implemented as library function or as system call. Some of them are discussed below:. 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.
The amount of error is usually more than one sampling period. I have followups enabled so if you respond maybe I can help more.
The flat profile gives the total execution time spent in each function and its percentage of the total running time. You can think the software is as fast as possible, when in fact it could be much faster. Use this Contact Form to get pgrof touch me with your comments, questions or suggestions about this site.
Kessler, and Marshall K. Thank you very much, keep up the good work! If a value is n times the sampling period, the expected error in the value is the square fnu of n sampling periods. The man page, by the way, suggests this:. Anonymous July 30,6: Well, I ran the proram again, ghu this time it produced the gmon. The man page, by the way, suggests this: Cody February 27,7: So you need it to exit from program termination normal termination. That measuring time of functions is good enough as opposed to lines of code or even instructions.
Mike Dunlavey Tprof 28,7: Output is sorted by percentage, with hot spots at the top of the list. Instrumentation code is automatically inserted into the program code during compilation gpgof example, by using the ‘-pg’ option of the gcc compilerto gather caller-function data.
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.
Hi Cody, You raise a lot of valid points, but let me itemize my objections to gprof. I think point 10 is exactly what I was getting at: This page was last edited on 21 Decemberat That the call graph is important as opposed to the information in stack samples.
Following test code will be used throughout the article:. But because difference in loops is small, every time program executes we can get different sort results in flat profile. Mutual recursion and non-trivial cycles are not resolvable by the gprof approach context-insensitive call graphbecause it only records arc traversal, not full call chains. At run-time, timing values are obtained by statistical sampling.
If there are some static functions whose profiling information you do not require then this can be achieved using -a option:. Mark Richter February 13,gu The only reason I came here is I was trying to remember why gmon. In this first step, we need to make sure that the profiling is enabled when the compilation gprov the code is done.
Rewording 3rd from last paragraph: This helps make your tprof execution faster which is always desired. In flat profile we expect that func1 works longer than func2.
GNU gprof – Table of Contents
I have been using gprof to isolate a performance issue in gproc large scale business application, but recent attempts to do this have stalled. Read more about Ramesh Natarajan and the blog.
A call to the monitor function ‘mcount’ is inserted before each function call. If you simply want to know which functions burn most of the cycles, it is stated concisely here. 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. Kiranjp September 3,gprkf From attaching to the program during execution where you need to investigateyou then have an idea well, often where the problem fprof in which case you can get closer to solving the problem.