Pinpointing bottlenecks in UI thread

ozcanay

I am observing that my UI is rather slow. I tried to offload as much work as possible off of the UI thread. Even though I got improvement, I still feel like it could be faster. Maybe I should profile the code. What is your strategy in this situation? Which tools/profilers are you using? I want to know which functions/code blocks incur overhead.

JonB

@ozcanay said in Pinpointing bottlenecks in UI thread:

Which tools/profilers are you using?

You won't get much pertinent answers if you don't say what platform you are interested in developing on!

Speaking for Linux, unfortunately I have to report they they, and Qt Creator, want you to use the Linux perf tool. While it may be very powerful, I was an experienced user with the older gprof and that worked fine and was easy to understand. IMHO perf is a nightmare to attempt to understand, not to mention to install and get working at the OS level. I think you need a degree in "perf-understanding" to get anywhere with it :( If you are Windows and using MSVC/Visual Studio you may be more successful with their inbuilt profiler.

A year or so ago I asked this community which profiling tools they used to analyse their Qt programs' performance, and was surprised/disappointed to be met by a deafening silence. The "community" seemed not to use performance analysis tools. I was as horrified as you might be! So good luck.....

I gave up on profiling and put in relevant QElapsedTimers around high-level bits, then moved them down to lower-level bits till I had a general idea of where time was being spent. Not ideal --- like using print/debug statements instead of stepping through a debugger --- but better than nothing.

ozcanay

I am on Linux. To be honest, I had looked in perf and it really was not easy to grasp for me, too. Did not look into gprof.

SGaist

Hi,

KDAB's Hotspot might help you with the use and analysis of perf.

JonB

@ozcanay
@SGaist's suggestions are always worth looking into! I had a quick glance, it includes this picture
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This is what I mean about you need a degree to decipher what perf is telling you! I don't have (much of) a clue what this is all about...!