Oct 26 2020 08:55 AM
Oct 26 2020 08:55 AM
We now have multiple customers where DWM.exe uses too much CPU randomly.
In our monitoring, we see spikes that DWM.exe uses 25% percent constant CPU (so 1 of the 4 cores in the VM) for a couple of hours, then it suddenly stops again.
When doing a CPU trace via Windows Performance Analyzer, we see that DWM.exe is using all this CPU via d3d10warp.dll.
It's happening in connected and also in disconnected sessions. Connecting / disconnecting does not seem to trigger it or stop it. We tried using a different VM size (Intel / AMD CPU), no effect. When the user logs off and logs on a again, problem seems to be fixed for a random period of time.
It seems to happen to some particular users most of the time (but sometimes also to random users once). We contacted these most-reported users, but they have no "special" client machines like 200% DPI, 4K displays, non-Windows clients, dark theme enabled etc. Just default settings, maximum 2x full HD monitor.
It also happened once to an administrator RDP session (connected via classic RDP, not via WVD).
Does anyone else have this problem? It seems our customers who are still running WVD Windows 10 v1903 are not experiencing this.
DWM using the CPU:
Feb 05 2021 09:44 AM
Feb 08 2021 12:28 AM
Yes, we did create a case at MS support, and it has been solved. Sorry for not reporting it here.
The problem was caused by soms HP Printer Driver utility on the WVD host, causing DWM.exe to use excessive CPU.
After deleting this printer driver, the issue was gone.
This was the reaction by MS support after sending them some log files of the affected host:
There are a total of 6 DWM.exe processes which are active when the trace was captured.
Out of these 3 were under normal usage, 1 was showing as low and there were two processes which were showing as high. While checking the stack tree for DWM.exe application we were able to see that Direct3D Image Rasterizer DLL which is D3D10Warp.dll is the file being used by DWM and next comes DWMCore.dll which is the source file for DWM.exe
We then matched the DISK Usage sample and CPU (Actual Usage Samples) from WPR and see that DWM.exe was constantly having high IOPS due to backgroundhost.exe application which then led us further to find the exact application causing the issue.
Backgroundhost.exe is the consent windows application that stays in the suspended state unless used by the application itself. We found that <AD2F1837.HPPrinterControl> is making this happen,
<AD2F1837.HPPrinterControl> (41012), 71.996121700, 6,070.100, 16.384, 1.
If you check the first value which 41012 which is the thread ID for this process, followed by CPU threshold (71.99) for 6 seconds and then followed by 6,070 which is IOPS count, and finally the wait time (in secs) that is exactly 16secs.
DWM is just a medium for rendering between system GUI and the application. We suggest you to disable or update this specific HPP Printer Control application and let us know if the issue exists.
Let me know if you have any query.