From: Sasha Levin <sasha.levin@oracle.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KVM General <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
lcapitulino@redhat.com
Subject: Re: kvm: odd time values since "kvmclock: set scheduler clock stable"
Date: Mon, 18 May 2015 19:45:41 -0400 [thread overview]
Message-ID: <555A79A5.608@oracle.com> (raw)
In-Reply-To: <20150518223936.GA4486@amt.cnet>
On 05/18/2015 06:39 PM, Marcelo Tosatti wrote:
> On Tue, May 12, 2015 at 07:17:24PM -0400, Sasha Levin wrote:
>> Hi all,
>>
>> I'm seeing odd jump in time values during boot of a KVM guest:
>>
>> [...]
>> [ 0.000000] tsc: Detected 2260.998 MHz processor
>> [3376355.247558] Calibrating delay loop (skipped) preset value..
>> [...]
>>
>> I've bisected it to:
>
> Paolo, Sasha,
>
> Although this might seem undesirable, there is no requirement
> for sched_clock to initialize at 0:
>
> "
> *
> * There is no strict promise about the base, although it tends to start
> * at 0 on boot (but people really shouldn't rely on that).
> *
> "
>
> Sasha, are you seeing any problem other than the apparent time jump?
Nope, but I've looked at it again and it seems that it jumps to the host's
clock (that is, in the example above the 3376355 value was the host's clock
value).
Thanks,
Sasha
next prev parent reply other threads:[~2015-05-18 23:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-12 23:17 kvm: odd time values since "kvmclock: set scheduler clock stable" Sasha Levin
2015-05-13 12:58 ` Luiz Capitulino
2015-05-13 15:38 ` Sasha Levin
2015-05-13 17:16 ` Paolo Bonzini
2015-05-18 22:39 ` Marcelo Tosatti
2015-05-18 23:45 ` Sasha Levin [this message]
2015-05-19 0:13 ` Marcelo Tosatti
2015-05-19 2:02 ` Sasha Levin
2015-05-19 2:13 ` Sasha Levin
2015-05-22 0:40 ` KVM: x86: zero kvmclock_offset when vcpu0 initializes kvmclock system MSR Marcelo Tosatti
2015-05-22 0:41 ` kvm: odd time values since "kvmclock: set scheduler clock stable" Marcelo Tosatti
2015-05-26 13:21 ` Luiz Capitulino
2015-05-26 13:25 ` Sasha Levin
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