Re: [PATCH tip/core/timers 4/4] timers: Reduce future __run_timers() latency for first add to empty list

2014-01-15 Thread Paul E. McKenney
On Wed, Jan 15, 2014 at 06:24:09PM +0100, Oleg Nesterov wrote: > On 01/14, Paul E. McKenney wrote: > > > > @@ -749,6 +749,7 @@ __mod_timer(struct timer_list *timer, unsigned long > > expires, > > > > base = lock_timer_base(timer, ); > > > > + (void)catchup_timer_jiffies(base); > > Agreed,

Re: [PATCH tip/core/timers 4/4] timers: Reduce future __run_timers() latency for first add to empty list

2014-01-15 Thread Oleg Nesterov
On 01/14, Paul E. McKenney wrote: > > @@ -749,6 +749,7 @@ __mod_timer(struct timer_list *timer, unsigned long > expires, > > base = lock_timer_base(timer, ); > > + (void)catchup_timer_jiffies(base); Agreed, but perhaps it would be better to do this before all_timers++ in

Re: [PATCH tip/core/timers 4/4] timers: Reduce future __run_timers() latency for first add to empty list

2014-01-15 Thread Oleg Nesterov
On 01/14, Paul E. McKenney wrote: @@ -749,6 +749,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, base = lock_timer_base(timer, flags); + (void)catchup_timer_jiffies(base); Agreed, but perhaps it would be better to do this before all_timers++ in

Re: [PATCH tip/core/timers 4/4] timers: Reduce future __run_timers() latency for first add to empty list

2014-01-15 Thread Paul E. McKenney
On Wed, Jan 15, 2014 at 06:24:09PM +0100, Oleg Nesterov wrote: On 01/14, Paul E. McKenney wrote: @@ -749,6 +749,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, base = lock_timer_base(timer, flags); + (void)catchup_timer_jiffies(base); Agreed, but perhaps

[PATCH tip/core/timers 4/4] timers: Reduce future __run_timers() latency for first add to empty list

2014-01-14 Thread Paul E. McKenney
From: "Paul E. McKenney" The __run_timers() function currently steps through the list one jiffy at a time in order to update the timer wheel. However, if the timer wheel is empty, no adjustment is needed other than updating ->timer_jiffies. Therefore, just before we add a timer to an empty

[PATCH tip/core/timers 4/4] timers: Reduce future __run_timers() latency for first add to empty list

2014-01-14 Thread Paul E. McKenney
From: Paul E. McKenney paul...@linux.vnet.ibm.com The __run_timers() function currently steps through the list one jiffy at a time in order to update the timer wheel. However, if the timer wheel is empty, no adjustment is needed other than updating -timer_jiffies. Therefore, just before we add a