Re: [tip:timers/urgent] Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME

From: Rafael J. Wysocki
Date: Wed Apr 25 2018 - 17:28:46 EST

On Wednesday, April 25, 2018 9:09:29 PM CEST Thomas Gleixner wrote:
> On Wed, 25 Apr 2018, Linus Torvalds wrote:
> > On Wed, Apr 25, 2018 at 6:45 AM, tip-bot for Thomas Gleixner
> > <tipbot@xxxxxxxxx> wrote:
> > >
> > > As stated in the pull request for the unification of CLOCK_MONOTONIC and
> > > CLOCK_BOOTTIME, it was clear that we might have to revert the change.
> >
> > I'm ok with the revert., but I do want the revert message to talk
> > about *exactly* what broke.
> >
> > I don't see the reported watchdog things, and I run systemd and I ran
> > these patches.
> With suspend/resume?
> > So it's not just "systemd uses this for a watchdog". It must be
> > something specific that made it trigger for some people and not
> > others, and it's that specific thing that we should document so that
> > we know why this simplification failed.
> Fair enough. Do the reporters have more information or do I have to chase
> it down myself?

Well, if CLOCK_MONOTONIC did not count when the system was suspended and now
it does that due to the change in question, then this is a significant
difference in behavior likely to confuse things even in principle.

While it may not confuse things on some systems after all, does this really