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We have a WPF application, that sporadically (rarely) becomes very sluggish. We've managed to capture a WPA trace (aka xperf), and it distinctly shows lags in application activity - and at the same time a distinct rise in dwm.exe activity.

I couldn't extract from the stacks any useful insights into what is going on. The application seems to spend a lot of time in the following stack:app stacks

And dwm seems to spend a lot of time in the following stack: enter image description here

Can anyone shed some light on what's slowing the app down?

Edit: here's the WPA pkg (350k), in case you'd be willing to take a look.

Ofek Shilon
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  • It sounds to me that your application is using software rendering on the target machine, is the app used via RDP? if so windows will dull it down for performance. Check [this article](https://msdn.microsoft.com/en-us/library/ms748373(v=vs.110).aspx) maybe it will help you. – XAMlMAX Apr 06 '17 at 22:30
  • @XAMlMAX thanks. Is there a way to programmaticaly detect whether the target machine indeed uses software rendering? – Ofek Shilon Apr 07 '17 at 07:27
  • the timeframe which you highlighted shows only a bit DWM cpu usage. if you want debug hangs, [check the PRECISE graph](https://channel9.msdn.com/Shows/Defrag-Tools/Defrag-Tools-43-WPT-Wait-Analysis) – magicandre1981 Apr 07 '17 at 14:52
  • @magicandre1981 I already looked at the wait chain via the precise cpu usage, and all I got is that my app and dwm wait on one another at various points. I now attach the WPA pkg of this timeframe - perhaps you'd be able to extract more info? – Ofek Shilon Apr 08 '17 at 05:49
  • without getting any hints it is hard to see anything. what is your app name? DWM calls nVIDIA drivers, so it still uses HW not software based rendering. so update the drivers fro your Geforce GTX 960. also even with 32GB RAM windows uses the new compression to free RAM wich also causes some perf impacts (higher cpu usage compared to DWM) – magicandre1981 Apr 08 '17 at 06:32
  • My app is cathworksUI.exe – Ofek Shilon Apr 08 '17 at 06:56
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    your app loads tons of data from C (Micron M6 SSD), but puts caches on slower HDD (D: a WD drive). and I see the commit usage of 30GB, so your Windows is under memory pressure and Windows tries to free RAM. The HP workstation supports 64GB RAM, so upgrade and look what happens. – magicandre1981 Apr 08 '17 at 11:57
  • @magicandre1981 Thank you very much. – Ofek Shilon Apr 12 '17 at 05:58

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