Ubuntu
virt-manager package

  1. Bug #1851062
  2. Comment #16

Comment 16 for bug 1851062

Revision history for this message
Kevin Locke (kevinoid) wrote :

I agree that QEMU shouldn't use much CPU when paused, regardless of VM settings. For reference, I narrowed down a (more) minimal test case:

Using the Windows 10 May 2020 English 64-bit ISO from https://www.microsoft.com/en-us/software-download/windows10ISO

qemu-system-x86_64 \
 -no-user-config \
 -machine pc-q35-5.0,accel=kvm \
 -m 1024 \
 -blockdev driver=file,node-name=win10iso,filename=Win10_2004_English_x64.iso \
 -device ide-cd,drive=win10iso \
 -no-hpet \
 -rtc driftfix=slew

then pause the VM after the "Windows Setup" window appears, qemu-system-x86_64 uses ~40% CPU. Without -rtc driftfix=slew, ~10%. Without -no-hpet, ~1%.

I added it to the ML discussion this morning to see if there was interest in fixing the issue, but so far no takers: https://lore.kernel.org/kvm/20200626151432.GA231100@kevinolos/