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hrtimer: Make offset update smarter

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On every tick/hrtimer interrupt we update the offset variables of the
clock bases. That's silly because these offsets change very seldom.

Add a sequence counter to the time keeping code which keeps track of
the offset updates (clock_was_set()). Have a sequence cache in the
hrtimer cpu bases to evaluate whether the offsets must be updated or
not. This allows us later to avoid pointless cacheline pollution.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20150414203501.132820245@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Thomas Gleixner 2015-04-14 21:08:37 +00:00
parent 21d6d52a1b
commit 868a3e915f
5 changed files with 26 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

4
include/linux/hrtimer.h
View file

@ -163,7 +163,7 @@ enum hrtimer_base_type {
* and timers
* @cpu: cpu number
* @active_bases: Bitfield to mark bases with active timers
* @clock_was_set: Indicates that clock was set from irq context.
* @clock_was_set_seq: Sequence counter of clock was set events
* @expires_next: absolute time of the next event which was scheduled
* via clock_set_next_event()
* @in_hrtirq: hrtimer_interrupt() is currently executing
@ -179,7 +179,7 @@ struct hrtimer_cpu_base {
raw_spinlock_t lock;
unsigned int cpu;
unsigned int active_bases;
unsigned int clock_was_set;
unsigned int clock_was_set_seq;
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires_next;
int in_hrtirq;