Storing next event and determining whether the base is idle can be done in
__next_timer_interrupt().
Preparatory patch for new call sites which need this information as well.
Signed-off-by: Thomas Gleixner <[email protected]>
---
kernel/time/timer.c | 43 ++++++++++++++++++++++++-------------------
1 file changed, 24 insertions(+), 19 deletions(-)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1358,8 +1358,11 @@ static int next_pending_bucket(struct ti
/*
* Search the first expiring timer in the various clock levels. Caller must
* hold base->lock.
+ *
+ * Stores the next expiry time in base. The return value indicates whether
+ * the base is empty or not.
*/
-static unsigned long __next_timer_interrupt(struct timer_base *base)
+static bool __next_timer_interrupt(struct timer_base *base)
{
unsigned long clk, next, adj;
unsigned lvl, offset = 0;
@@ -1416,7 +1419,10 @@ static unsigned long __next_timer_interr
clk >>= LVL_CLK_SHIFT;
clk += adj;
}
- return next;
+ /* Store the next event in the base */
+ base->next_expiry = next;
+ /* Return whether the base is empty or not */
+ return next == base->clk + NEXT_TIMER_MAX_DELTA;
}
/*
@@ -1465,7 +1471,7 @@ u64 get_next_timer_interrupt(unsigned lo
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
u64 expires = KTIME_MAX;
unsigned long nextevt;
- bool is_max_delta;
+ bool is_empty;
/*
* Pretend that there is no timer pending if the cpu is offline.
@@ -1475,9 +1481,8 @@ u64 get_next_timer_interrupt(unsigned lo
return expires;
spin_lock(&base->lock);
- nextevt = __next_timer_interrupt(base);
- is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
- base->next_expiry = nextevt;
+ is_empty = __next_timer_interrupt(base);
+ nextevt = base->next_expiry;
/*
* We have a fresh next event. Check whether we can forward the
* base. We can only do that when @basej is past base->clk
@@ -1490,20 +1495,17 @@ u64 get_next_timer_interrupt(unsigned lo
base->clk = nextevt;
}
- if (time_before_eq(nextevt, basej)) {
- expires = basem;
- base->is_idle = false;
- } else {
- if (!is_max_delta)
- expires = basem + (nextevt - basej) * TICK_NSEC;
- /*
- * If we expect to sleep more than a tick, mark the base idle:
- */
- if ((expires - basem) > TICK_NSEC)
- base->is_idle = true;
- }
+ /* Base is idle if the next event is more than a tick away. */
+ base->is_idle = time_after(nextevt, basej + 1);
spin_unlock(&base->lock);
+ if (!is_empty) {
+ /* If we missed a tick already, force 0 delta */
+ if (time_before_eq(nextevt, basej))
+ nextevt = basej;
+ expires = basem + (nextevt - basej) * TICK_NSEC;
+ }
+
return cmp_next_hrtimer_event(basem, expires);
}
@@ -1534,7 +1536,10 @@ static int collect_expired_timers(struct
* the next expiring timer.
*/
if ((long)(jiffies - base->clk) > 2) {
- unsigned long next = __next_timer_interrupt(base);
+ unsigned long next;
+
+ __next_timer_interrupt(base);
+ next = base->next_expiry;
/*
* If the next timer is ahead of time forward to current
On Tue, Apr 18, 2017 at 01:11:05PM +0200, Thomas Gleixner wrote:
> Storing next event and determining whether the base is idle can be done in
> __next_timer_interrupt().
>
> Preparatory patch for new call sites which need this information as well.
>
> Signed-off-by: Thomas Gleixner <[email protected]>
> ---
> kernel/time/timer.c | 43 ++++++++++++++++++++++++-------------------
> 1 file changed, 24 insertions(+), 19 deletions(-)
>
> --- a/kernel/time/timer.c
> +++ b/kernel/time/timer.c
> @@ -1358,8 +1358,11 @@ static int next_pending_bucket(struct ti
> /*
> * Search the first expiring timer in the various clock levels. Caller must
> * hold base->lock.
> + *
> + * Stores the next expiry time in base. The return value indicates whether
> + * the base is empty or not.
> */
> -static unsigned long __next_timer_interrupt(struct timer_base *base)
> +static bool __next_timer_interrupt(struct timer_base *base)
Can't say I'm a fan of this.. I sort of see where this is going, but the
fact remains that __next_timer_interrupt(), as a function, makes me
expect a return value of time/timer quantity.
On Wed, Apr 19, 2017 at 08:50:39AM +0200, Peter Zijlstra wrote:
> On Tue, Apr 18, 2017 at 01:11:05PM +0200, Thomas Gleixner wrote:
> > Storing next event and determining whether the base is idle can be done in
> > __next_timer_interrupt().
> >
> > Preparatory patch for new call sites which need this information as well.
> >
> > Signed-off-by: Thomas Gleixner <[email protected]>
> > ---
> > kernel/time/timer.c | 43 ++++++++++++++++++++++++-------------------
> > 1 file changed, 24 insertions(+), 19 deletions(-)
> >
> > --- a/kernel/time/timer.c
> > +++ b/kernel/time/timer.c
> > @@ -1358,8 +1358,11 @@ static int next_pending_bucket(struct ti
> > /*
> > * Search the first expiring timer in the various clock levels. Caller must
> > * hold base->lock.
> > + *
> > + * Stores the next expiry time in base. The return value indicates whether
> > + * the base is empty or not.
> > */
> > -static unsigned long __next_timer_interrupt(struct timer_base *base)
> > +static bool __next_timer_interrupt(struct timer_base *base)
>
> Can't say I'm a fan of this.. I sort of see where this is going, but the
> fact remains that __next_timer_interrupt(), as a function, makes me
> expect a return value of time/timer quantity.
Maybe we can just do a rename like fetch_next_timer_interrupt() or
update_next_timer_interrupt()?