linux-kernel - Re: [PATCH 0/3] timekeeping: Improved NOHZ frequency steering (v2)

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Date:   Wed, 17 May 2017 17:03:02 +0200
From:   Miroslav Lichvar <mlichvar@...hat.com>
To:     John Stultz <john.stultz@...aro.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Richard Cochran <richardcochran@...il.com>,
        Prarit Bhargava <prarit@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Paul Mackerras <paulus@...ba.org>,
        Anton Blanchard <anton@...ba.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Tony Luck <tony.luck@...el.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [PATCH 0/3] timekeeping: Improved NOHZ frequency steering (v2)

On Fri, May 12, 2017 at 10:26:12AM -0700, John Stultz wrote:
> On Fri, May 12, 2017 at 8:14 AM, Miroslav Lichvar <mlichvar@...hat.com> wrote:
> > I see this with real PHCs and PTP/NTP synchronization too. It's very
> > confusing when the timekeeping changes so much for no apparent reason.
> > If we can't remove the old vsyscalls yet, I was thinking maybe a new
> > flag could be added to adjtimex to report the error, so applications
> > can at least detect this problem and consider stepping the clock in
> > order to reset the error?
> >
> > Thoughts?
> 
> I'd rather not have short-term hacks that applications have to adapt.
> So I think we should drop the old vsyscall method in the near term.
> Sorry this sort of fell off my radar.

Ok. Sounds good.

> Do you have an updated set of patches you want to get ready to address
> the issue? We can get those reviewed while we increase the pressure on
> dropping the OLD_VSYSCALL implementations.

I'll send an RFC series shortly.

Thanks,

-- 
Miroslav Lichvar