Hello, When I run a cyclictest with a small interval in a guest, even though the guest's cpu load is small (2-3%) the host qemu-system thread is showing 100% cpu utilization, almost all of it being "system/kernel". There seems to be a threshold effect: - on my system an interval of 220us creates no problem (host qemu-system thread is 4% user and 1% system) - an interval of 210us shows the host qemu-system thread at 4% user and 50% system) - an interval of 200us makes the host qemu-system thread at 4% user and 95% system Those threshold values are probably not universal... I'm using kvm with qemu on x86-64, and this issue seems easily reproducible (yocto with a 5.15rt kernel, debian stable with a 5.10rt kernel, or a non-rt 5.10 or a backported 5.16rt kernel, etc.). I reproduced this issue on a debian stable non-RT kernel to be sure the problem was not due to preempt-rt. My cmdlines for host and guest are very basic: ipv6.disable=1 efi=runtime Vcpupinning does not change the outcome. I'd love to understand the cause of this behavior and if there's something to be done to solve this. Thanks a lot. Florent.
