Date: Tue, 22 Jul 2014 18:29:40 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Pawel Moll <pawel.moll@arm.com>
Cc: John Stultz <john.stultz@linaro.org>, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, Oleg Nesterov <oleg@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>, Andy Lutomirski <luto@amacapital.net>,
        Stephen Boyd <sboyd@codeaurora.org>, Baruch Siach <baruch@tkos.co.il>,
        Thomas Gleixner <tglx@linutronix.de>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] sched_clock: Track monotonic raw clock
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On Tue, Jul 22, 2014 at 05:17:23PM +0100, Pawel Moll wrote:
> > Now, I already mentioned max error bounds, and I've not yet looked at
> > your actual control loop, but that is something to keep in mind, we want
> > something that's limited.
> 
> Indeed. Richard has already expressed concerns that my coefficients
> won't work everywhere (as in with different clock rate ratios) and he's
> most likely right. My money is on a more advanced, "self-tuning"
> solution, where we definitely need an escape condition.

I was wanting to look up software PLLs, as I seem to remember that's
what NTP and PTP use, but Richard should know I think.

Its not really a subject I've looked at before.
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