From: Gabriel Beddingfield <gabe@nestlabs.com>
To: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Stephen Boyd <sboyd@codeaurora.org>,
Alessandro Zummo <a.zummo@towertech.it>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
linux-rtc@vger.kernel.org, Guy Erb <guy@nestlabs.com>,
Howard Harte <hharte@nestlabs.com>
Subject: Re: Extreme time jitter with suspend/resume cycles
Date: Thu, 5 Oct 2017 09:46:06 -0700 [thread overview]
Message-ID: <CAOdF7nt8aOUie_qF7Uryyvo6eOxv3E9KdWL1Ju+afaiDODHOAA@mail.gmail.com> (raw)
In-Reply-To: <CALAqxLUnpNQrduA09V4uAe=3-57UU9g9Qyaqg7PE9RnNjGAVeA@mail.gmail.com>
Hi John,
First, my apologies for calling it a "hack." I just went back and looked at the
commit history and this is first-class stuff... and you explained it very well
(including the NTP interaction) in the commit message. I'm pretty sure I
read this before, but I reckon most of it went over my head and I garbled it.
On Wed, Oct 4, 2017 at 5:20 PM, John Stultz <john.stultz@linaro.org> wrote:
> Yea. I thought arm devices often had read_persistent_clock64() backed
> by the 32k timer (which is poor for time initialization but works well
> for suspend timing).
>
> Maybe I misunderstood on the first read. Is it then that the
> relatively fine-grained read_persistent_clock64() is colliding with
> the delta_delta logic that assumes we get coarse 1sec resolution? In
> that case the huristic above seems sane.
Yes, exactly.
-gabe
next prev parent reply other threads:[~2017-10-05 16:46 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-04 16:11 Extreme time jitter with suspend/resume cycles Gabriel Beddingfield
2017-10-04 18:22 ` Thomas Gleixner
2017-10-04 23:10 ` Gabriel Beddingfield
2017-10-05 0:20 ` John Stultz
2017-10-05 16:46 ` Gabriel Beddingfield [this message]
2017-10-05 11:01 ` Thomas Gleixner
2017-10-05 16:47 ` Gabriel Beddingfield
2017-10-05 18:01 ` Thomas Gleixner
2017-10-05 20:51 ` Gabriel Beddingfield
2017-10-05 21:04 ` Thomas Gleixner
2017-10-05 21:12 ` Gabriel Beddingfield
2017-10-05 21:33 ` Thomas Gleixner
2017-10-05 0:16 ` John Stultz
2017-10-05 11:05 ` Thomas Gleixner
2017-10-05 14:11 ` Thomas Gleixner
2017-10-05 11:08 ` Miroslav Lichvar
2017-10-05 20:14 ` Gabriel Beddingfield
2017-10-05 21:31 ` Thomas Gleixner
2017-10-15 6:39 ` Introduce clock precision to help time travelers was " Pavel Machek
2017-10-18 20:34 ` Alan Cox
2017-10-18 21:08 ` Pavel Machek
2017-10-18 21:26 ` Alexandre Belloni
2017-10-18 21:56 ` Pavel Machek
2017-11-04 15:34 ` Alexandre Belloni
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