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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So we see that a flat profile containing information related to only function func1 is displayed. Anyway, as for why it would hang, a question and a suggestion on figuring out where its having issues: Vivek Kumar December 30,9: That invocation counting is useful as opposed to getting inclusive time percent.
Table of Contents
But because difference in loops is small, every time program gprf we can get different sort results in flat profile. 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. Output is sorted by percentage, with hot spots at the top of the list.
From GProf to DTrace “2. Andreas August 25,2: Lets try and understand the three steps listed above through a practical example. There were analogous utility in glibc called ‘sprof’ to profile dynamic libraries. Read more about Ramesh Natarajan and the blog. Kessler, and Marshall K. Sampling data is saved in ‘gmon.
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. Some of them are discussed below:. 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.
The only reason Gju came here is I was trying to remember why gmon.
Note that one can explicitly specify the output file like in example above or the information is produced on stdout. Yes, I understand the limitations of most program analysis tools. I have followups enabled so if you respond maybe I can help more. Also, your program needs to have sufficient permissions for gmon.
Oh no, the world is NOT perfect and only glrof fool would think otherwise or think that only gptof is valuable. So you need it to exit from program termination normal termination.
Use this Contact Form to get in touch me with your comments, questions or suggestions about this site. There is an external tool called gprof2dot capable of converting the call graph from gprof into graphical form.
I think it is better to make bigger time discrete in functions. Just mentioning that because I see that complaint a lot. From attaching to the program during execution where you need to investigateyou then have an idea well, often gnj the problem is in which case you can get closer to solving the problem. That measuring time of functions hnu good enough as opposed to lines of code or even instructions.
Gprof – Wikipedia
Function call counts are also reported. Notify me of followup comments via e-mail. You must use this option when compiling the source files you want data about, and you must also use it when linking. It is easy to use,clearly and instructive. There is also an estimate of how gpfof time was spent in the subroutines of each function. Hi Mike, Well your points are also valid.
GPROF Tutorial – How to use Linux GNU GCC Profiling Tool
Mark Richter February 28,5: If a value is n times the sampling period, the expected error in the value is the square root of n sampling periods. Contact Us Email Me: That accuracy of measurement ynu important as opposed to accuracy of identifying speedup opportunities. This helps make your program execution faster which is always desired. That the call graph is important as opposed to the information in stack samples.
That self time matters as opposed to inclusive time, which includes self time. The call graph shows, for each function, which functions called it, which other functions it called, and how many times. I could go into greater detail on any of these if necessary. 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.
This file contains a couple of tables flat profile and call graph in addition to gnh other information.
I think point 10 is exactly what I was getting at: Hi Cody, You raise a lot of valid points, but let me itemize my objections to gprof. Mike Dunlavey February 28,7: Webarchive template wayback links.
The individual columns tnu the flat profile as well as call graph are very well explained in the output itself.
Following test code will be used throughout the article:.