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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This never happens when the non-profiling version is run. Function call counts are also reported. Use this Contact Form to get in touch me with your comments, questions or suggestions about this site. Lets have a look at this text file:. But because difference in loops is small, every time program executes we can get different sort results in flat profile.
The flat profile is mainly about self time, which in a large program is usually irrelevant because the real problems are mid-stack. As you would gnh 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.
Table of Contents
Kiranjp Ghu 3,1: Cody February 27,7: GPROF is not very good for what you need. I have followups enabled so if you respond maybe I can help more. Note that while execution if the program changes the current working directory using chdir then gmon. This can suggest places where you might try to eliminate function calls that use a lot of time.
Mark Richter February 13, I will be posting instruction guides, how-to, troubleshooting tips and tricks on Linux, database, hardware, security and web. You raise a lot of valid points, but bprof me itemize my objections to gprof.
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.
In this first step, we need to make sure that the profiling is enabled when the compilation of the code is done. The individual columns for the flat profile as well as call graph are very well explained in the output itself. Anonymous March 21,4: The flat profile gives the total execution time spent in each function and its percentage of the total running grpof.
Output is sorted by percentage, with hot spots at the top of the list.
GNU gprof – Table of Contents
Rasna October 17, Yes, I pgrof the limitations of most program analysis tools. Hi Cody, You raise a lot of valid points, but let me itemize my objections to gprof. So you need it to exit from program termination normal termination. Journey of a Data Packet in the Internet.
Why would the profiling version hang up at the end of program execution like that? 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. Responding to your revised third paragraph: Anyway, as for why it would hang, a question and a suggestion on figuring out where its having issues:.
That the call graph is important as opposed to the information in stack samples. Notify me of followup comments via e-mail. A call to the monitor function ‘mcount’ is inserted before each function call. From GProf to DTrace “2. 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.
As a quick addendum: That program counter sampling is useful as opposed to stack sampling. Also, if 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.
Unlike prof, gprof is capable of limited call graph gprot and printing. Not to be confused with the perfect hash function generator gperf. Now lets see the analysis output:.