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From: Thomas Gleixner <tglx@linutronix.de>
To: John Stultz <john.stultz@linaro.org>
Cc: Christopher Hall <christopher.s.hall@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	jesus.sanchez-palencia@intel.com,
	Gavin Hindman <gavin.hindman@intel.com>,
	liam.r.girdwood@intel.com, Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Miroslav Lichvar <mlichvar@redhat.com>
Subject: Re: TSC to Mono-raw Drift
Date: Thu, 1 Nov 2018 18:44:57 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.21.1811011841060.1642@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CALAqxLUKOYYm=bzn4owZC_UgWTqrVPiz2TSnLFm1RNak3tm8-g@mail.gmail.com>

On Tue, 23 Oct 2018, John Stultz wrote:
> On Fri, Oct 19, 2018 at 3:36 PM, John Stultz <john.stultz@linaro.org> wrote:
> I spent a little bit of time thinking this out. Unfortunately I don't
> think its a simple matter of calculating the granularity error on the
> raw clock and adding it in each interval. The other trouble spot is
> that the adjusted clocks (monotonic/realtime) are adjusted off of that
> raw clock. So they would need to have that error added as well,
> otherwise the raw and a otherwise non-adjusted monotonic clock would
> drift.
> 
> However, to be correct, the ntp adjustments made would have to be made
> to both the base interval + error, which mucks the math up a fair bit.

Hmm, confused as usual. Why would you need to do anything like that?

Thanks,

	tglx

  parent reply	other threads:[~2018-11-01 17:45 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20181015160945.5993-1-christopher.s.hall@intel.com>
2018-10-19 15:25 ` Thomas Gleixner
2018-10-19 18:34   ` John Stultz
2018-10-19 18:39     ` John Stultz
2018-10-19 18:37   ` Thomas Gleixner
2018-10-19 18:48     ` John Stultz
2018-10-19 18:57       ` Thomas Gleixner
2018-10-19 19:21         ` John Stultz
2018-10-19 20:50           ` Thomas Gleixner
2018-10-19 22:36             ` John Stultz
2018-10-23 18:31               ` John Stultz
2018-10-24 14:51                 ` Miroslav Lichvar
2018-10-24 17:32                   ` Christopher Hall
2018-10-25 11:49                     ` Miroslav Lichvar
2018-11-01 17:41                   ` Thomas Gleixner
2018-11-02 10:26                     ` Miroslav Lichvar
2018-11-02 11:27                       ` Thomas Gleixner
2018-11-01 17:44                 ` Thomas Gleixner [this message]
2018-11-01 17:56                   ` John Stultz
2018-11-01 18:03                     ` Thomas Gleixner
2018-11-02 11:20                       ` Miroslav Lichvar
2018-11-02 11:25                         ` Thomas Gleixner
2018-11-02 12:31                           ` Miroslav Lichvar

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