UsingValgrind < BETA

[[http://valgrind.org/][Valgrind]] is a software suite that includes many useful tools, like a memory checker and a cache profiler.

---+++++ Installation
I'm not really sure how to install this on Windows. I've only installed this on my own machine running Ubuntu 9.10. To install, just open a terminal and type:
   * =sudo apt-get install valgrind= and it should do the rest.
I also find [[http://kcachegrind.sourceforge.net/html/Home.html][KCacheGrind]] to be a very useful tool for visualizing the output of Callgrind. Installation instructions can be found [[http://kcachegrind.sourceforge.net/html/Installation.html][here]], but I also just used apt-get:
   * =sudo apt-get install kcachegrind=.

---+++++ Memcheck usage
Memcheck is used for checking for memory leaks and memory errors, and is also useful for debugging segmentation faults. Basic usage of memcheck is:
   * Compile your code with =-g -O0= flags. =-g= enables debugging mode and allows memcheck to display line numbers. =-O0= compiles with no optimizations; higher levels can be used, but you might get false positives. Memcheck recommends using less than level O2.
      * Note: compiling with these flags can be done by setting the =CMAKE_CXX_FLAGS= and =CMAKE_C_FLAGS= variables in the main =CMakeLists.txt= file. Better yet, set a =CMAKE_CXX_FLAGS_DEBUG= and =CMAKE_C_FLAGS_DEBUG= and configure using =ccmake= to use compile a Debug version.
   * Run =valgrind [program]=, where =[program]= is what you would normally type to run your program, including all flags and arguments. This will give you a summary of memory leaks and basic memory errors.
   * If you get memory leaks, try running =valgrind --leak-check=full [program]= to see exactly where leaks are happening. I believe this will make your program run a lot slower, so you may have to sit around and wait for a while. If it's too slow, try compiling with a higher optimization level.

[[http://valgrind.org/docs/manual/mc-manual.html#mc-manual.overview][Here]]'s a nice overview of memcheck in general. Section 4.2 will give you a basic description of all the error messages, while section 4.3 will give you more command line options.

---+++++ Callgrind usage
Callgrind is used for profiling your program. To use:
   * Compile code with =-g= flag.
   * Run =valgrind --tool=callgrind [program]=, where =[program]= is what you would normally type to run your program, including all flags and arguments.
   * A file should be generated in your current working directory called =callgrind.out.[pid]=, where =[pid]= is the pid of the process you just profiled.
   * If you have kCacheGrind installed, you should be able to run the file just by double-clicking it, or type in the console: =kcachegrind callgrind.out.[pid]=.
   * If everything worked, you should now get a nice GUI view of your program's profile.
      * "Incl." is the time the function/method takes to run + the time all the functions it calls takes to run.
      * "Self" is the time the function/method takes to run excluding all functions it calls.
      * "Called" is the number of times the function was called.
This topic: BETA > TipsAndTricks > WebHome > NGSAlignerProject > UsingValgrind
Topic revision: r2 - 2010-05-25 - jayzhang