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From: Suleiman Souhlal <suleiman@google.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	rkrcmar@redhat.com, john.stultz@linaro.org, sboyd@kernel.org,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	kvm@vger.kernel.org, Tomasz Figa <tfiga@google.com>
Subject: Re: [RFC 0/2] kvm: Use host timekeeping in guest.
Date: Tue, 24 Sep 2019 17:08:53 +0900	[thread overview]
Message-ID: <CABCjUKA4gPScr7oTWMpthtH-tz51Z8_cUvm6r779Y-G_qCHo=Q@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1909201221070.1858@nanos.tec.linutronix.de>

On Fri, Sep 20, 2019 at 7:23 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> On Fri, 20 Sep 2019, Paolo Bonzini wrote:
>
> > On 20/09/19 08:27, Suleiman Souhlal wrote:
> > > To do that, I am changing kvmclock to request to the host to copy
> > > its timekeeping parameters (mult, base, cycle_last, etc), so that
> > > the guest timekeeper can use the same values, so that time can
> > > be synchronized between the guest and the host.
> > >
> > > Any suggestions or feedback would be highly appreciated.
> >
> > I'm not a timekeeping maintainer, but I don't think the
> > kernel/time/timekeeping.c changes are acceptable.
>
> Indeed. #ifdef WHATEVERTHEHECK does not go anywhere. If at all this needs
> to be a runtime switch, but I have yet to understand the whole picture of
> this.

Yeah, I will try to make this a runtime switch.

As for the PTP driver, I don't think it will work for us because we
need CLOCK_MONOTONIC and CLOCK_BOOTTIME to match the host, and from my
understanding, PTP doesn't solve that.

Thanks,
-- Suleiman

      reply	other threads:[~2019-09-24  8:09 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-20  6:27 [RFC 0/2] kvm: Use host timekeeping in guest Suleiman Souhlal
2019-09-20  6:27 ` [RFC 1/2] kvm: Mechanism to copy host timekeeping parameters into guest Suleiman Souhlal
2019-09-20  6:27 ` [RFC 2/2] x86/kvmclock: Use host timekeeping Suleiman Souhlal
2019-09-20 13:33   ` Vitaly Kuznetsov
2019-09-24  8:10     ` Suleiman Souhlal
2019-09-24 11:14       ` Vitaly Kuznetsov
2019-09-20  7:48 ` [RFC 0/2] kvm: Use host timekeeping in guest Paolo Bonzini
2019-09-20 10:23   ` Thomas Gleixner
2019-09-24  8:08     ` Suleiman Souhlal [this message]

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