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    SubjectRe: cputime takes cstate into consideration
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    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.



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