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Date: Thu, 5 Oct 2017 09:46:06 -0700 From: Gabriel Beddingfield <gabe@...tlabs.com> To: John Stultz <john.stultz@...aro.org> Cc: Thomas Gleixner <tglx@...utronix.de>, LKML <linux-kernel@...r.kernel.org>, Stephen Boyd <sboyd@...eaurora.org>, Alessandro Zummo <a.zummo@...ertech.it>, Alexandre Belloni <alexandre.belloni@...e-electrons.com>, linux-rtc@...r.kernel.org, Guy Erb <guy@...tlabs.com>, Howard Harte <hharte@...tlabs.com> Subject: Re: Extreme time jitter with suspend/resume cycles 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@...aro.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
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