From: Thomas Gleixner <tglx@linutronix.de>
To: Richard Cochran <richardcochran@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>,
Christopher Hall <christopher.s.hall@intel.com>,
Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
"x86@kernel.org" <x86@kernel.org>,
intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
lkml <linux-kernel@vger.kernel.org>,
kevin.b.stanton@intel.com
Subject: Re: [PATCH v4 1/4] Produce system time from correlated clocksource
Date: Tue, 20 Oct 2015 21:11:21 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.11.1510202107410.8159@nanos> (raw)
In-Reply-To: <20151020145523.GA5207@netboy>
On Tue, 20 Oct 2015, Richard Cochran wrote:
> On Tue, Oct 20, 2015 at 01:51:13PM +0200, Richard Cochran wrote:
> > You can, in fact, achieve "proper" correlation by sampling. As John
> > said, the question is whether the method in the patch set "measurably
> > improves the error" over using another, simpler method.
>
> Here is a short example to put some numbers on the expected error.
> Let the driver sample at an interval of 1 ms. If the system time's
> frequency hasn't changed between two samples, A and B, then the driver
> may interpolate without introducing any error.
Darn, we don't want to have that kind of sampling in every driver
which has this kind of problem even if it looks like the simpler
choice for this particular use case. This is going to be something
which next generation chips will have on more than just the audio
interface and we realy want to have a generic solution for this.
Thanks,
tglx
next prev parent reply other threads:[~2015-10-20 19:12 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-12 18:45 [PATCH v4 0/4] Patchset enabling hardware based cross-timestamps for next gen Intel platforms Christopher S. Hall
2015-10-12 18:45 ` [PATCH v4 1/4] Produce system time from correlated clocksource Christopher S. Hall
2015-10-13 4:58 ` Richard Cochran
2015-10-13 7:51 ` Thomas Gleixner
2015-10-13 8:31 ` Richard Cochran
2015-10-13 19:15 ` Thomas Gleixner
2015-10-13 21:12 ` Richard Cochran
2015-10-14 7:21 ` Thomas Gleixner
2015-10-14 9:29 ` Richard Cochran
2015-10-14 14:22 ` Thomas Gleixner
2015-10-14 16:18 ` Richard Cochran
2015-10-15 2:34 ` Christopher Hall
2015-10-15 5:41 ` Richard Cochran
2015-10-15 8:13 ` Thomas Gleixner
2015-10-13 5:26 ` Richard Cochran
2015-10-13 13:50 ` Richard Cochran
2015-10-13 19:42 ` Thomas Gleixner
2015-10-15 1:57 ` Christopher Hall
2015-10-15 5:57 ` Richard Cochran
2015-10-15 8:15 ` Thomas Gleixner
2015-10-20 0:18 ` Christopher Hall
2015-10-20 0:36 ` John Stultz
2015-10-20 8:54 ` Richard Cochran
2015-10-20 10:48 ` Thomas Gleixner
2015-10-20 11:51 ` Richard Cochran
2015-10-20 14:55 ` Richard Cochran
2015-10-20 19:11 ` Thomas Gleixner [this message]
2015-10-20 19:36 ` Richard Cochran
2015-10-20 20:16 ` John Stultz
2015-10-21 7:44 ` Thomas Gleixner
2015-11-03 19:18 ` Stanton, Kevin B
2015-11-09 21:17 ` John Stultz
2015-10-12 18:45 ` [PATCH v4 2/4] Always running timer " Christopher S. Hall
2015-10-13 2:03 ` kbuild test robot
2015-11-18 23:53 ` Jacob Pan
2015-10-12 18:45 ` [PATCH v4 3/4] Add PTP_SYS_OFFSET_PRECISE for driver crosstimestamping Christopher S. Hall
2015-10-13 13:59 ` Richard Cochran
2015-10-15 2:47 ` Christopher Hall
2015-11-07 2:15 ` Christopher Hall
2015-10-12 18:45 ` [PATCH v4 4/4] Adds hardware supported cross timestamp Christopher S. Hall
2015-10-13 2:10 ` kbuild test robot
2015-10-13 2:11 ` kbuild test robot
2015-10-13 2:31 ` David Miller
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