From mboxrd@z Thu Jan  1 00:00:00 1970
From: Richard Cochran <richardcochran@gmail.com>
Subject: Re: [PATCH 1/5] Add functions producing system time given a backing
 counter value
Date: Wed, 29 Jul 2015 13:48:41 +0200
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Cc: Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <john.stultz@linaro.org>,
	Christopher Hall <christopher.s.hall@intel.com>,
	Ingo Molnar <mingo@redhat.com>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	john.ronciak@intel.com, "H. Peter Anvin" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	lkml <linux-kernel@vger.kernel.org>, netdev@vger.kernel.org
To: Peter Zijlstra <peterz@infradead.org>
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On Wed, Jul 29, 2015 at 12:49:44PM +0200, Peter Zijlstra wrote:
> This is still fuzzy, right? The hardware ART timestamp could be from
> _before_ the NTP adjust; or the NTP adjust could happen while we do this
> conversion and we'll take the retry loop.

In the original series, yes.
 
> In both cases, the resulting value is computed using a different slope
> than was in effect at the time of the stamp. With the end result being
> slightly off from what it should be.

In Thomas' patch the get_ts() is meant to read fresh pairs of time
stamps from within the loop.


Thanks,
Richard