| Message ID | 20170418111400.589271247@linutronix.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
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 <tglx@linutronix.de> > --- > 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 <tglx@linutronix.de> > > --- > > 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()?
--- 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
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 <tglx@linutronix.de> --- kernel/time/timer.c | 43 ++++++++++++++++++++++++------------------- 1 file changed, 24 insertions(+), 19 deletions(-)