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

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Message-ID: <1858767.c2KKoU8fl2@aspire.rjw.lan>
Date:   Wed, 25 Apr 2018 11:49:51 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Thomas Gleixner <tglx@...utronix.de>,
        John Stultz <john.stultz@...aro.org>
Cc:     Genki Sky <sky@...ki.is>, David Herrmann <dh.herrmann@...il.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Pavel Machek <pavel@....cz>, linux-pm@...r.kernel.org
Subject: Re: [RFC/RFT patch 0/7] timekeeping: Unify clock MONOTONIC and clock BOOTTIME

On Wednesday, April 25, 2018 10:52:18 AM CEST Rafael J. Wysocki wrote:
> On Tuesday, April 24, 2018 10:09:28 AM CEST Thomas Gleixner wrote:
> > On Mon, 23 Apr 2018, John Stultz wrote:
> > 
> > > On Mon, Apr 23, 2018 at 7:45 PM, Genki Sky <sky@...ki.is> wrote:
> > > > Quoting Genki Sky (2018/04/23 20:40:36 -0400)
> > > >> I came across this thread for same reason as [0]: Daemons getting
> > > >> killed by systemd on resume (after >WatchdogSec seconds of
> > > >> suspending). I'm using master branch of systemd and the kernel. As
> > > >> mentioned, systemd uses CLOCK_MONOTONIC, originally expecting it to
> > > >> not include suspend time.
> > > >>
> > > >> Correct me if I'm mistaken, but I don't see the ambiguity of whether
> > > >> this patch series breaks systemd. If it's implemented correctly, you'd
> > > >> hope it *would* break it!
> > > >
> > > > This sounded a little weak on re-reading, sorry. So, I just confirmed
> > > > that after booting a "git revert -m 1 680014d6d1da", the issue no
> > > > longer appears. (I.e., a suspend for >WatchDog sec doesn't result in
> > > > any daemon getting killed).
> > > >
> > > > Let me know if I can help in any way.
> > > 
> > > Yea, this is the sort of thing I was worried about.
> > > 
> > > Thomas: I think reverting this change is needed.
> > 
> > Sigh. I hoped that something like this would be catched before I sent the
> > pull request by those who were actually interested in this change...
> 
> The "git revert -m 1 680014d6d1da" makes resume issues on my Aspire S5
> go away (cf. https://marc.info/?l=linux-kernel&m=152460804018920&w=2).
> 
> I'll try with just the "monotonic" vs "boottime" clock changes reverted.

FWICS (so far) system resume still works here with the commits between
d6ed449afdb3 (timekeeping: Make the MONOTONIC clock behave like the BOOTTIME
clock) and 127bfa5f4342 (hrtimer: Unify MONOTONIC and BOOTTIME clock behavior)
inclusive reverted on top of 4.17-rc2.  [I probably should revert commit
92af4dcb4e1c (tracing: Unify the "boot" and "mono" tracing clocks) too, but
it doesn't revert cleanly and it doesn't apprear to affect things here too.]