[RESOLVED] Win7: 100% CPU usage when laptop is docked

Just a quick post on an issue brought to my attention by Nuno, one of my Portugese collegues. Thanks! :)

The issue: whenever the laptop was docked, CPU usage % would go up to a 100%, without being able to attribute this to a particular process. I always tell people to troubleshoot high CPU usage issues using Xperf, so that is what I asked my collegue to do. When looking at the Xperf traces he made I noticed that DPC usage was quite high consistently. When drilling down into what routine was involved, I noticed the USBPORT_XDPC_WORKER routine was at the top. This tied in with my theory that the issue could have something to do with USB, since it only occurred in a docked state.

Querying our internal databases led me to the following hotfix:

981214 There is high CPU usage when using a USB audio device connected to a USB 2.0 EHCI host controller
https://support.microsoft.com/default.aspx?scid=kb;EN-US;981214

This matched perfectly with the USB headset being plugged into the back of the docking station. The 981214 hotfix is included in the recent USB Rollup Package, available under Optional Updates on Windows Update:

2529073 Binary files in some USB drivers are not updated after you install Windows 7 SP1 or Windows Server 2008 R2 SP1
https://support.microsoft.com/default.aspx?scid=kb;en-US;2529073

We confirmed that after installing 2529073 the issue did not occur anymore. Case closed. :)