linux-kernel - Re: [RFC/RFT patch 0/7] timekeeping: Unify clock MONOTONIC and clock BOOTTIME

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Date:   Tue, 13 Mar 2018 11:11:25 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Petr Mladek <pmladek@...e.com>,
        Mark Salyzyn <salyzyn@...roid.com>,
        Prarit Bhargava <prarit@...hat.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Kevin Easton <kevin@...rana.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Jonathan Corbet <corbet@....net>
Subject: Re: [RFC/RFT patch 0/7] timekeeping: Unify clock MONOTONIC and clock BOOTTIME

On Mon, Mar 12, 2018 at 11:36 PM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Linus Torvalds <torvalds@...ux-foundation.org> wrote:
>
>> On Thu, Mar 1, 2018 at 8:33 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
>> >
>> > This really needs lot of testing, documentation updates and more input from
>> > userspace folks to make a final decision.
>>
>> Honestly, I don't think we'd get the testing this kind of change needs
>> except by just trying it.
>>
>> I'm willing to merge this in the 4.17 merge window, with the
>> understanding that if people end up reporting issues, we may just have
>> to revert it all, and chalk it up to a learning experience - and add
>> the appropriate commentary in the kernel code about exactly what it
>> was that depended on that MONO/BOOT difference.
>>
>> One non-technical thing I would ask: use some other word than
>> "conflate". Maybe just "combine". Or better yet, "unify".
>
> Ok, I have edited all the changelogs accordingly (and also flipped around the
> 'clock MONOTONIC' language to the more readable 'the MONOTONIC clock' variant),
> the resulting titles are (in order):
>
>  72199320d49d: timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock
>  d6ed449afdb3: timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock
>  f2d6fdbfd238: Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior
>  d6c7270e913d: timekeeping: Remove boot time specific code
>  7250a4047aa6: posix-timers: Unify MONOTONIC and BOOTTIME clock behavior
>  127bfa5f4342: hrtimer: Unify MONOTONIC and BOOTTIME clock behavior
>  92af4dcb4e1c: tracing: Unify the "boot" and "mono" tracing clocks
>
> I'll push these out after testing.

I'm still anxious about userspace effects given how much I've seen the
current behavior documented, and wouldn't pushed for this myself (I'm
a worrier), but at least I'm not seeing any failures in initial
testing w/ kselftest so far.

thanks
-john