On 27/12/2017 19:55, Andrew Davis wrote: > > In a nutshell: > > * OpenBSD dev claims QEMU/KVM local APIC emulation is broken. > * OpenBSD dev states that OpenBSD uses local APIC to interrupt every > 10ms in "repeated mode". > * OpenBSD dev claims that other systems (Linux, FreeBSD) likely do not > use the local APIC in "repeated mode". > > I'm not familiar enough with low-level development to verify or confirm > these claims. > > I've tried tweaking some different settings on the guest and host, such > as disabling the HPET timer and x2apic, neither of which has proven > effective. > > Adding "kvm-intel.preemption_timer=0" on the host kernel commandline > seems to resolve the timing issue. However, I had at least one host that > wouldn't reboot cleanly with this flag enabled. Ok, this is interesting. Please gather a trace using trace-cmd record -e kvm -c -P pid-of-qemu for about 10 seconds; run it once right after booting, once when it starts taking 2 seconds, one when it starts taking 4 seconds. The traces are big but should compress well. Thanks, Paolo > This is only an issue on OpenBSD. Other guest operating systems (CentOS, > Ubuntu, FreeBSD) on the same machine do not exhibit this behavior.
