From: Sean Christopherson <seanjc@google.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Dongli Zhang <dongli.zhang@oracle.com>,
Joe Jin <joe.jin@oracle.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, pbonzini@redhat.com,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com
Subject: Re: [PATCH RFC 1/1] KVM: x86: add param to update master clock periodically
Date: Tue, 3 Oct 2023 17:10:22 -0700 [thread overview]
Message-ID: <ZRytbih4TUVkEhLC@google.com> (raw)
In-Reply-To: <96ceb6a6e9c380d329e8cd556ad13a2fcd554882.camel@infradead.org>
On Tue, Oct 03, 2023, David Woodhouse wrote:
> On Mon, 2023-10-02 at 17:53 -0700, Sean Christopherson wrote:
> >
> > This is *very* lightly tested, as in it compiles and doesn't explode, but that's
> > about all I've tested.
>
> I don't think it's working, if I understand what it's supposed to be
> doing.
...
> When I run xen_shinfo_test, the kvmclock still drifts from the
> "monotonic_raw" I get from kvm_get_time_and_clockread(), even with your
> patch.
It "works", in that it does what I intended it to do. What I missed, and what's
obvious in hindsight, is that the timekeeping code doesn't *just* update what KVM
uses as the "base" when there "big events" like suspend/resume, the timekeeping
code updates the base clock on every tick.
My hack only smoothed away the delta, it didn't address the time that had gotten
moved into the base. I though the base would be stable if the host was in a
steady state, but see above...
prev parent reply other threads:[~2023-10-04 0:10 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-26 23:06 [PATCH RFC 1/1] KVM: x86: add param to update master clock periodically Dongli Zhang
2023-09-27 0:29 ` Joe Jin
2023-09-27 0:36 ` Dongli Zhang
2023-09-28 16:18 ` Sean Christopherson
2023-09-29 20:15 ` Dongli Zhang
2023-10-02 8:33 ` David Woodhouse
2023-10-02 16:37 ` Sean Christopherson
2023-10-02 17:17 ` Dongli Zhang
2023-10-02 18:18 ` Sean Christopherson
2023-10-02 21:06 ` Peter Zijlstra
2023-10-02 21:16 ` Peter Zijlstra
2023-10-02 18:16 ` David Woodhouse
2023-10-03 0:53 ` Sean Christopherson
2023-10-03 1:32 ` Dongli Zhang
2023-10-03 1:49 ` Sean Christopherson
2023-10-03 2:07 ` Dongli Zhang
2023-10-03 21:00 ` Sean Christopherson
2023-10-03 5:54 ` David Woodhouse
2023-10-04 0:04 ` Sean Christopherson
2023-10-04 10:01 ` David Woodhouse
2023-10-04 18:06 ` Sean Christopherson
2023-10-04 19:13 ` Dongli Zhang
2023-10-11 0:20 ` Sean Christopherson
2023-10-11 7:18 ` David Woodhouse
2023-10-13 18:07 ` Sean Christopherson
2023-10-13 18:21 ` David Woodhouse
2023-10-13 19:02 ` Sean Christopherson
2023-10-13 19:12 ` David Woodhouse
2023-10-13 20:03 ` Sean Christopherson
2023-10-13 20:12 ` Dongli Zhang
2023-10-13 23:26 ` Sean Christopherson
2023-10-14 9:49 ` David Woodhouse
2023-10-16 15:47 ` Dongli Zhang
2023-10-16 16:25 ` David Woodhouse
2023-10-16 17:04 ` Dongli Zhang
2023-10-16 18:49 ` Sean Christopherson
2023-10-16 22:04 ` Dongli Zhang
2023-10-16 22:48 ` Sean Christopherson
2023-10-17 16:18 ` Dongli Zhang
2023-10-03 9:12 ` David Woodhouse
2023-10-04 0:07 ` Sean Christopherson
2023-10-04 8:06 ` David Woodhouse
2023-10-03 14:29 ` David Woodhouse
2023-10-04 0:10 ` Sean Christopherson [this message]
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