Kcachegrind output file

You can navigate through the functions by double clicking in the call graph. In the last snapshot, I show the funky callee map which I expect will look better in the PDF version of the magazine in colour than in the black and white print magazine. The areas of the rectangles is proportional to the time spent in the function. Both the map and the list are dynamic, and you can click in one and the area or list item will be highlighted in the other.

You can also double click to jump to a different function. This is worse for 32bit x86, where by default code gets generated to use the venerable x87 floating point coprocessor.

This uses 10byte 80bit precision internally. Valgrind performs the calculations at 64bit precision, so some of the intermediate precision is lost. Another problem with big real-world programs is speed. Like all of the Valgrind tools, there is a big overhead in performing the measurement. You can mitigate this by controlling when callgrind performs data collection. You can statically control callgrind using Valgrind macros defined in callgrind. You will probably need to do some profiling of the entire application to get an idea of where you want to concentrate your efforts.

Template by Bootstrapious. Ported to Hugo by DevCows. Hosting provided by Bytemark. On the left is the function call list. You typically click main here. In the bottom-right pane, you see the functions called by the function you chose in the left pane main in this case. It doesn't account for other process activity although this is probably desirable when considering a single program. It doesn't account for virtual-to-physical address mappings; hence the entire simulation is not a true representation of what's happening in the cache.

It doesn't account for cache misses not visible at the instruction level, eg. Valgrind will schedule threads differently from how they would be when running natively. This could warp the results for threaded programs.

These instructions seem to be rare so hopefully this won't affect accuracy much. Another thing worth nothing is that results are very sensitive. Changing the size of the valgrind. Variations will be small, but don't expect perfectly repeatable results if your program changes at all. While these factors mean you shouldn't trust the results to be super-accurate, hopefully they should be close enough to be useful.

Would be nice to exclude these somehow. Valgrind User Manual. Cachegrind: a cache profiler. Table of Contents 4. Cache profiling 4. Overview 4. Cache simulation specifics 4. Profiling programs 4. Output file 4. Cachegrind options 4. Annotating assembler programs 4. Warnings 4. Things to watch out for 4. Accuracy 4. Cache profiling. L1 instruction cache reads and misses; L1 data cache reads and read misses, writes and write misses; L2 unified cache reads and read misses, writes and writes misses.

Cache simulation specifics. Profiling programs. Output file. Cachegrind options. Command: the command line invocation of the program under examination.

Events recorded: event abbreviations are: Ir : I cache reads ie. From the profiled program concord. From libraries eg. Annotating assembler programs. Things to watch out for. If annotating at the assembler level, you might see something like this: 1 0 0. Learn more. Asked 5 years ago. Active 4 years, 11 months ago. Viewed 3k times. Callgrind output files are well generated, their content looks ok, but I'm unable to open them with kcachegrind: I get the following error message: Could not open file "callgrind.

Greg82 Greg82 2 2 gold badges 10 10 silver badges 23 23 bronze badges. Add a comment. Active Oldest Votes. Author: weidendo Date: Tue Jan 10 New Revision: Log: Add a format marker to callgrind files KCachegrind currently uses a quick format detection before actually loading a file, and checks for a line starting with "events:" in the first 2kB for that.

It is not too late to fix this issue for the callgrind format. This was effectively the case: I had a lot of files in argument of my program. You must build valgrind and kcachegrind from the svn and git repositories.