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Date:   Wed, 26 Jun 2019 21:21:00 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Raslan, KarimAllah" <karahmed@amazon.de>
Cc:     "tglx@linutronix.de" <tglx@linutronix.de>,
        "konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
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        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
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        "ankur.a.arora@oracle.com" <ankur.a.arora@oracle.com>,
        "rkrcmar@redhat.com" <rkrcmar@redhat.com>
Subject: Re: cputime takes cstate into consideration
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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.