From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zachary Amsden <zamsden@redhat.com>
Subject: Re: last_kernel_ns ?
Date: Mon, 04 Oct 2010 11:49:00 -1000
Message-ID: <4CAA4BCC.2010303@redhat.com>
References: <20101004165004.GI1230@mothafucka.localdomain>
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Cc: kvm@vger.kernel.org, mtosatti@redhat.com, avi@redhat.com
To: Glauber Costa <glommer@redhat.com>
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On 10/04/2010 06:50 AM, Glauber Costa wrote:
> Zach,
>
>          vcpu->hv_clock.tsc_timestamp = tsc_timestamp;
>          vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset;
>          vcpu->last_kernel_ns = kernel_ns;<===== (1)
>          vcpu->last_guest_tsc = tsc_timestamp;
>          vcpu->hv_clock.flags = 0;
>
> If I understand your intention corretly, you should add kvmclock_offset to (1).
> Am I misinterpreting something?
>    

No, last_kernel_ns is the last observed value of kernel_ns, not system 
time.  The kvmclock_offset may be modified since observation (unlikely, 
yet possible), and should not be considered in this computation.