Ticket #7796 (new defect)
Iffy serial port cause >95% CPU usage in a VM
|Reported by:||jimoe||Owned by:|
linux 18.104.22.168-0.5-desktop x86_64
USRobotics FAX/modem 5637
The serial port is enabled and set for COM1. The "Port Mode" is set to "Host Device" and the "Port/File Path" is USBACM0.
When the VM starts up, it complains that the COM port is "iffy" (paraphrase) and may not work. It does in fact work and quite well. However, the VM is spinning in a loop somewhere because the CPU usage for one core (of a quad processor) averages about 95%. Good thing it's a quad core CPU. The actual core in use switches around but at any one time a core is running close to maximum. The CPU usage within the VM guest itself is normal, less than 5%.
If I disable the serial port, the VM's CPU usage drops back to normal (5 - 10%).