Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/timers 3/3] timers: Reduce future __run_timers() latency for first add to empty list | Date | Mon, 13 Jan 2014 20:15:19 -0800 |
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From: "Paul E. McKenney" <paulmck@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 timer to an empty timer wheel, we should mark the timer wheel as being up to date. This marking will reduce (and perhaps eliminate) the jiffy-stepping that a future __run_timers() call will need to do in response to some future timer posting or migration. This commit therefore updates ->timer_jiffies for this case.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- kernel/timer.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/timer.c b/kernel/timer.c index 2b2e235ea7f1..e539dbf5b9c5 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -745,6 +745,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, base = lock_timer_base(timer, &flags); + (void)catchup_timer_jiffies(base); ret = detach_if_pending(timer, base, false); if (!ret && pending_only) goto out_unlock; -- 1.8.1.5
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