Re: [PATCH v9 07/10] time: hrtimer: Introduce hrtimer_next_event_without()

Frederic Weisbecker
2018-04-08T17:58:54Z

On Sun, Apr 08, 2018 at 10:20:30AM +0200, Rafael J. Wysocki wrote:
> On Saturday, April 7, 2018 4:46:38 PM CEST Frederic Weisbecker wrote:
> > On Wed, Apr 04, 2018 at 10:45:39AM +0200, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > >
> > > The next set of changes will need to compute the time to the next
> > > hrtimer event over all hrtimers except for the scheduler tick one.
> > >
> > > To that end introduce a new helper function,
> > > hrtimer_next_event_without(), for computing the time until the next
> > > hrtimer event over all timers except for one and modify the underlying
> > > code in __hrtimer_next_event_base() to prepare it for being called by
> > > that new function.
> > >
> > > No intentional changes in functionality.
> > >
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > ---
> > >
> > > v8 -> v9:
> > > * Make fewer changes to the existing code.
> > > * Add a new helper function for the handling of the use case at hand.
> > >
> > > ---
> > > include/linux/hrtimer.h | 1
> > > kernel/time/hrtimer.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++--
> > > 2 files changed, 54 insertions(+), 2 deletions(-)
> > >
> > > Index: linux-pm/include/linux/hrtimer.h
> > > ===================================================================
> > > --- linux-pm.orig/include/linux/hrtimer.h
> > > +++ linux-pm/include/linux/hrtimer.h
> > > @@ -426,6 +426,7 @@ static inline ktime_t hrtimer_get_remain
> > > }
> > >
> > > extern u64 hrtimer_get_next_event(void);
> > > +extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
> > >
> > > extern bool hrtimer_active(const struct hrtimer *timer);
> > >
> > > Index: linux-pm/kernel/time/hrtimer.c
> > > ===================================================================
> > > --- linux-pm.orig/kernel/time/hrtimer.c
> > > +++ linux-pm/kernel/time/hrtimer.c
> > > @@ -490,6 +490,7 @@ __next_base(struct hrtimer_cpu_base *cpu
> > > while ((base = __next_base((cpu_base), &(active))))
> > >
> > > static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
> > > + const struct hrtimer *exclude,
> > > unsigned int active,
> > > ktime_t expires_next)
> > > {
> > > @@ -502,9 +503,24 @@ static ktime_t __hrtimer_next_event_base
> > >
> > > next = timerqueue_getnext(&base->active);
> > > timer = container_of(next, struct hrtimer, node);
> > > + if (timer == exclude) {
> > > + /* Get to the next timer in the queue. */
> > > + struct rb_node *rbn = rb_next(&next->node);
> > > +
> > > + next = rb_entry_safe(rbn, struct timerqueue_node, node);
> > > + if (!next)
> > > + continue;
> >
> > Minor cosmectic detail again, timerqueue_iterate_next() would do the job and
> > avoid browsing timerqueue details.
>
> And below is a patch to make this change on top of the original.
>
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Subject: [PATCH] time: hrtimer: Use timerqueue_iterate_next() to get to the next timer
>
> Use timerqueue_iterate_next() to get to the next timer in
> __hrtimer_next_event_base() without browsing the timerqueue
> details diredctly.
>
> No intentional changes in functionality.
>
> Suggested-by: Frederic Weisbecker <frederic@kernel.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Thanks!