On 08/03/2017 11:57, Christoffer Dall wrote: > Hi Paolo, > > I'm looking at improving KVM/ARM a bit by calling guest_exit_irqoff > before enabling interrupts when coming back from the guest. > > Unfortunately, this appears to mess up my view of CPU usage using > something like htop on the host, because it appears all time is spent > inside the kernel. > > From my analysis, I think this is because we never handle any interrupts > before enabling interrupts, where the x86 code does its > handle_external_intr, and the result on ARM is that we never increment > jiffies before doing the vtime accounting. > > So my current idea is to increment jiffies according to the clocksource > before calling guest_exit_irqoff, but this would require some main > clocksource infrastructure changes. > > My question is: how important is the vtime accounting on the host from > your point of view? Worth poking the timekeeping folks about or even > trying to convince ourselves that the handle_external_intr thing is > worth it? Not really my area, so let's ask Rik. :) Paolo
