From: Paolo Bonzini <pbonzini@redhat.com>
To: Roman Kagan <rkagan@virtuozzo.com>,
kvm@vger.kernel.org, "Denis V. Lunev" <den@openvz.org>,
Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH kvm-unit-tests] KVM: x86: add hyperv clock test case
Date: Fri, 22 Apr 2016 20:08:47 +0200 [thread overview]
Message-ID: <571A68AF.1030907@redhat.com> (raw)
In-Reply-To: <20160422133240.GA9108@rkaganb.sw.ru>
On 22/04/2016 15:32, Roman Kagan wrote:
> The first value is derived from the kvm_clock's tsc_to_system_mul and
> tsc_shift, and matches hosts's vcpu->hw_tsc_khz. The second is
> calibrated using emulated HPET. The difference is those +14 ppm.
>
> This is on i7-2600, invariant TSC present, TSC scaling not present.
>
> I'll dig further but I'd appreciate any comment on whether it was within
> tolerance or not.
The solution to the bug is to change the Hyper-V reference time MSR to
use the same formula as the Hyper-V TSC-based clock. Likewise,
KVM_GET_CLOCK and KVM_SET_CLOCK should not use ktime_get_ns().
Paolo
next prev parent reply other threads:[~2016-04-22 18:08 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 14:04 [PATCH kvm-unit-tests] KVM: x86: add hyperv clock test case Paolo Bonzini
2016-01-28 14:04 ` Paolo Bonzini
2016-01-28 14:25 ` Andrey Smetanin
2016-01-28 14:50 ` Paolo Bonzini
2016-01-28 15:53 ` Paolo Bonzini
2016-01-28 18:45 ` Roman Kagan
2016-01-28 18:53 ` Roman Kagan
2016-01-28 21:28 ` Paolo Bonzini
2016-01-28 16:22 ` Roman Kagan
2016-02-03 16:37 ` Paolo Bonzini
2016-02-04 9:33 ` Roman Kagan
2016-02-04 10:13 ` Paolo Bonzini
2016-02-04 11:12 ` Roman Kagan
2016-04-21 17:01 ` Roman Kagan
2016-04-22 13:32 ` Roman Kagan
2016-04-22 18:08 ` Paolo Bonzini [this message]
2016-04-25 8:47 ` Roman Kagan
2016-04-26 10:34 ` Roman Kagan
2016-05-25 18:33 ` Roman Kagan
2016-05-26 14:47 ` Roman Kagan
2016-05-29 22:34 ` Marcelo Tosatti
-- strict thread matches above, loose matches on Subject: below --
2016-02-08 15:18 [PATCH 0/4] kvmclock: improve accuracy Paolo Bonzini
2016-02-08 15:18 ` [PATCH 1/4] KVM: x86: rename argument to kvm_set_tsc_khz Paolo Bonzini
2016-02-11 15:01 ` Marcelo Tosatti
2016-02-08 15:18 ` [PATCH 2/4] KVM: x86: rewrite handling of scaled TSC for kvmclock Paolo Bonzini
2016-02-11 15:23 ` Marcelo Tosatti
2016-02-08 15:18 ` [PATCH 3/4] KVM: x86: pass kvm_get_time_scale arguments in hertz Paolo Bonzini
2016-02-08 15:18 ` [PATCH 4/4] KVM: x86: track actual TSC frequency from the timekeeper struct Paolo Bonzini
2016-02-09 18:41 ` Owen Hofmann
2016-02-10 13:57 ` Paolo Bonzini
2016-02-16 13:48 ` Marcelo Tosatti
2016-02-16 14:25 ` Marcelo Tosatti
2016-02-16 16:59 ` Paolo Bonzini
2016-02-19 14:12 ` Marcelo Tosatti
2016-02-19 15:53 ` Paolo Bonzini
2016-02-16 14:00 ` [PATCH 0/4] kvmclock: improve accuracy Marcelo Tosatti
2016-08-31 14:13 [PATCH kvm-unit-tests] KVM: x86: add hyperv clock test case Roman Kagan
2016-09-01 16:07 ` Paolo Bonzini
2016-09-01 16:07 Paolo Bonzini
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