From: Richard Cochran <richardcochran@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
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
Subject: Re: [PATCH 1/5] Add functions producing system time given a backing counter value
Date: Wed, 29 Jul 2015 13:48:41 +0200 [thread overview]
Message-ID: <20150729114840.GA16880@localhost.localdomain> (raw)
In-Reply-To: <20150729104944.GM19282@twins.programming.kicks-ass.net>
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
next prev parent reply other threads:[~2015-07-29 11:48 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 0:46 [PATCH 0/5] Patchset enabling hardware based cross-timestamps for next gen Intel platforms Christopher Hall
2015-07-28 0:46 ` [PATCH 1/5] Add functions producing system time given a backing counter value Christopher Hall
2015-07-28 3:44 ` John Stultz
2015-07-28 4:05 ` John Stultz
2015-07-29 10:19 ` Thomas Gleixner
2015-07-29 10:23 ` Thomas Gleixner
2015-07-29 10:51 ` Peter Zijlstra
2015-07-29 12:30 ` Richard Cochran
2015-07-29 10:49 ` Peter Zijlstra
2015-07-29 11:48 ` Richard Cochran [this message]
2015-07-29 12:35 ` Peter Zijlstra
2015-07-29 12:52 ` Thomas Gleixner
2015-07-29 1:41 ` Hall, Christopher S
2015-07-29 14:05 ` Thomas Gleixner
2015-07-28 0:46 ` [PATCH 2/5] Added functions mapping TSC value to system time Christopher Hall
2015-07-28 0:46 ` [PATCH 3/5] Add calls to translate Always Running Timer (ART) " Christopher Hall
2015-07-28 1:32 ` Andy Lutomirski
2015-07-29 1:18 ` Hall, Christopher S
2015-07-29 1:47 ` Andy Lutomirski
2015-07-28 4:11 ` John Stultz
2015-07-29 2:05 ` Hall, Christopher S
2015-07-29 8:25 ` Paul Bolle
2015-07-28 0:46 ` [PATCH 4/5] Add support for driver cross-timestamp to PTP_SYS_OFFSET ioctl Christopher Hall
2015-07-28 0:46 ` [PATCH 5/5] Enables cross timestamping in the e1000e driver Christopher Hall
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