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» Profiling Rocks - KDevelop CMake Support now 20x faster

Wed, 03/31/2010 - 01:24

I just need to get this out quickly:

We were aware that KDevelop’s CMake support was slow. Too slow actually. It was profiled months ago and after a quick look that turned up QRegExp, it was discarded in fear of having to rewrite the whole parser properly, without using QRegExp. Which btw. is still a good idea of course.

But well, today I felt like I should do some more tinkering. I mean I managed to optimize KDevelop’s Cpp support recently (parsing Boost’s huge generated template headers, like e.g. vector200.hpp is now 30% faster). I managed to make KGraphViewer usable for huge callgraphs I produce in Massif Visualizer. So how hard could it be to make KDevelop’s CMake at least /a bit/ faster, he?

Yeah well an hour later and two commits later, I managed to find and fix two bottlenecks. Both where related to QRegExp. Neither was the actual parser, instead it was the part that evaluated CMake files, esp. the STRING(...) function. So even if we’d used a proper parser generator, this would still been slow.

The first one was the typical “don’t reinvent the wheel” kinda commit which already made the CMake support two times faster for projects that used FindQt4.cmake, i.e. any Qt or KDE project. Not bad, right? Well, while I fixed that I saw that KDevelop tried to do some Regular expression replacement on the output of qmake --help, this could not been right, could it? With help of Andreas and Aleix we found the bug in the parser and that made the CMake support 10 times faster.

So yeah, CMake projects using Qt or KDE should now get opened a whopping 20 times faster in KDevelop :)

I really love KCacheGrind and Valgrind’s callgrind - again it proved to be the most awesome tool one can imagine! If you are interested in the callgrind files:

  1. without optimization
  2. first optimization
  3. second optimization

Note: with KCacheGrind from trunk you can open these compressed files transparently :)

» Transparent loading of compressed Callgrind files in KCacheGrind

Thu, 03/11/2010 - 23:43

Hey everyone!

I just committed an (imo) insanely useful feature for KCacheGrind: Transparent loading of compressed Callgrind files. Finally one does not have to keep those Callgrind files around uncompressed, hogging up lots of space. And what is even more important: It’s much easier to share these files now, as you can send or upload them as .gz or better yet .bz2 and open them directly. KDE architecture just rocks :) So in KDE 4.5 the best profiling visualizer just got better :D

In related news: I’m spending my time as intern at KDAB currently by creating an application to visualize Massif. If you are interested, check the sources out on gitorious: http://gitorious.org/massif-visualizer

It’s still pretty limited in what it offers, yet is probably already more useful than the plain ASCII graph that ms_print generates:


Visualization of a Massif output file

This is very WIP but the visuals are somewhat working now. I plan to make the whole graph react on user input, i.e. zoomable, click to show details about snapshots, show information about the heap items that make up the stacked part of the diagram, …

Also very high on my wish list is some kind of interaction with the KCacheGrind libraries, to reuse it’s nice features like callgraphs, cost maps, etc. pp. you name it :) All these features that make KCacheGrind such an insanely useful application.

Oh and remember: Never do performance optimizations without checking the facts first ;-)