How To Install Gprof On Ubuntu Live Cd
If your goal is to use a profiler, use one of the suggested ones.However, if you're in a hurry and you can manually interrupt your program under the debugger while it's being subjectively slow, there's a simple way to find performance problems.Just halt it several times, and each time look at the call stack. If there is some code that is wasting some percentage of the time, 20% or 50% or whatever, that is the probability that you will catch it in the act on each sample. So that is roughly the percentage of samples on which you will see it.
There is no educated guesswork required.If you do have a guess as to what the problem is, this will prove or disprove it.You may have multiple performance problems of different sizes. If you clean out any one of them, the remaining ones will take a larger percentage, and be easier to spot, on subsequent passes.This magnification effect, when compounded over multiple problems, can lead to truly massive speedup factors.Caveat: Programmers tend to be skeptical of this technique unless they've used it themselves.
They will say that profilers give you this information, but that is only true if they sample the entire call stack, and then let you examine a random set of samples. (The summaries are where the insight is lost.) Call graphs don't give you the same information, because.
they don't summarize at the instruction level, and. they give confusing summaries in the presence of recursion.They will also say it only works on toy programs, when actually it works on any program, and it seems to work better on bigger programs, because they tend to have more problems to find.They will say it sometimes finds things that aren't problems, but that is only true if you see something once. If you see a problem on more than one sample, it is real.P.S. This can also be done on multi-thread programs if there is a way to collect call-stack samples of the thread pool at a point in time, as there is in Java.P.P.S As a rough generality, the more layers of abstraction you have in your software, the more likely you are to find that that is the cause of performance problems (and the opportunity to get speedup).Added: It might not be obvious, but the stack sampling technique works equally well in the presence of recursion. @Crash: I won't debate the 'poor man' part:-) It's true that statistical measurement precision requires many samples, but there are two conflicting goals - measurement and problem location. I'm focussing on the latter, for which you need precision of location, not precision of measure. So for example, there can be, mid-stack, a single function call A; that accounts for 50% of time, but it can be in another large function B, along with many other calls to A that are not costly.
Precise summaries of function times can be a clue, but every other stack sample will pinpoint the problem.–May 23 '09 at 1:14. I would use Valgrind and Callgrind as a base for my profiling tool suite. What is important to know is that Valgrind is basically a Virtual Machine:(wikipedia) Valgrind is in essence a virtualmachine using just-in-time (JIT)compilation techniques, includingdynamic recompilation.
Nothing fromthe original program ever gets rundirectly on the host processor.Instead, Valgrind first translates theprogram into a temporary, simpler formcalled Intermediate Representation(IR), which is a processor-neutral,SSA-based form. After the conversion,a tool (see below) is free to dowhatever transformations it would likeon the IR, before Valgrind translatesthe IR back into machine code and letsthe host processor run it.Callgrind is a profiler build upon that. Main benefit is that you don't have to run your aplication for hours to get reliable result. Even one second run is sufficient to get rock-solid, reliable results, because Callgrind is a non-probing profiler.Another tool build upon Valgrind is Massif. I use it to profile heap memory usage.
It works great. What it does is that it gives you snapshots of memory usage - detailed information WHAT holds WHAT percentage of memory, and WHO had put it there.
Such information is available at different points of time of application run. The answer to run valgrind -tool=callgrind is not quite complete without some options. We usually do not want to profile 10 minutes of slow startup time under Valgrind and want to profile our program when it is doing some task.So this is what I recommend.
Ubuntu Server Live Usb
Run program first: valgrind -tool=callgrind -dump-instr=yes -v -instr-atstart=no./binary tmpNow when it works and we want to start profiling we should run in another window: callgrindcontrol -i onThis turns profiling on. To turn it off and stop whole task we might use: callgrindcontrol -kNow we have some files named callgrind.out. in current directory. To see profiling results use: kcachegrind callgrind.out.I recommend in next window to click on 'Self' column header, otherwise it shows that 'main' is most time consuming task. 'Self' shows how much each function itself took time, not together with dependents.
Ubuntu Bootable Dvd
Welcome to LinuxQuestions.org, a friendly and active Linux Community.You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free.
Today!Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.Are you new to LinuxQuestions.org? Visit the following links: If you have any problems with the registration process or your account login, please.
If you need to reset your password,.Having a problem logging in? Please visit to clear all LQ-related cookies.
Introduction to Linux - A Hands on GuideThis guide was created as an overview of the Linux Operating System, geared toward new users as an exploration tour and getting started guide, with exercises at the end of each chapter.For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration. This book contains many real life examples derived from the author's experience as a Linux system and network administrator, trainer and consultant.
They hope these examples will help you to get a better understanding of the Linux system and that you feel encouraged to try out things on your own.to receive this Complete Guide absolutely free.