Re: [PATCH 2/4] time: add a notifier chain for when the system timeis stepped

From: Thomas Gleixner
Date: Mon Jun 24 2013 - 15:55:57 EST


On Mon, 24 Jun 2013, David Vrabel wrote:

> On 24/06/13 17:30, Thomas Gleixner wrote:
> >
> > We already have a synchronous notifier in place and the notifier call
> > itself is not expensive. What's expensive is the hypercall and there
> > is no way at the moment to figure out whether the update is relevant
> > for you or just a tick. Though that's trivial information to provide
> > without imposing another notifier including the surrounding mess on
> > the core code.
>
> This looks good, thanks.
>
> > --- a/kernel/time/timekeeping.c
> > +++ b/kernel/time/timekeeping.c
> [...]
> > @@ -508,7 +509,7 @@ int do_settimeofday(const struct timespec *tv)
> >
> > tk_set_xtime(tk, tv);
> >
> > - timekeeping_update(tk, true, true);
> > + timekeeping_update(tk, true, true, true);
>
> These three booleans in a row is getting a bit opaque. How about I also
> change it to a set of flags? e.g.,
>
> timekeeping_updated(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);

Fair enough. Can you convert the existing booleans first and then put
the CLOCK_WAS_SET patch on top of that?

Thanks,

tglx

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