On Wed, Mar 17, 2021 at 05:11:22PM +0100, Reinoud Zandijk wrote: > Hi, > > when executing Qemu with > > qemu-system-x86_64 -m 4G -smp cores=2 -M q35 -snapshot \ > -drive file=/home/reinoud/Downloads/Win10-demo.raw,format=raw \ > -rtc base=localtime,clock=host -spice port=5924,disable-ticketing=on \ > -vga qxl -usb -device usb-tablet -net nic -net tap,ifname=tap0,script=no > > my cpu usage in Windows10 *allways* reports 100% cpu usage. On the host system > its always 190%+ ie it is really taking two cores completely. > > Using our NVMM accelerator makes it run a whole lot faster, as good as native > speed, but it always takes up the whole two processors too! Windows10 also > *allways* reports 100% cpu usage. Its not a startup thing for even when > letting it run for quite some time never reduces the cpu time. > > In contrast, running NetBSD in the VM takes no CPU time at all when idle. > > When Googling about this, I saw this come by quite often. Is there something > Qemu can do about this? What makes it spin like this and why is it Windows10 > specific? This is a specific VM aware version too if I may believe it saying > so. I already replaced drivers to virtio etc but to no avail. Always 100% CPU > time for all CPUs. > > Could this also be an ACPI thing?
IIRC, "-usb" still adds a USB-1 controller and that's known to be bad for causing high load in Windows guests in particular. So before debugging anything else, I'd suggest configuring a USB-3 controller instead - see docs/usb2.txt XHCI info. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
