On Wed, 2019-06-26 at 21:21 +0200, Peter Zijlstra wrote: > On Wed, Jun 26, 2019 at 06:55:36PM +0000, Raslan, KarimAllah wrote: > > > > > If the host is completely in no_full_hz mode and the pCPU is dedicated to a > > single vCPU/task (and the guest is 100% CPU bound and never exits), you would > > still be ticking in the host once every second for housekeeping, right? Would > > not updating the mwait-time once a second be enough here? > > People are trying very hard to get rid of that remnant tick. Lets not > add dependencies to it. > > IMO this is a really stupid issue, 100% time is correct if the guest > does idle in pinned vcpu mode. One use case for proper accounting (obviously for a slightly relaxed definition or *proper*) is *external* monitoring of CPU utilization for scaling group (i.e. more VMs will be launched when you reach a certain CPU utilization). These external monitoring tools needs to account CPU utilization properly. Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879
