timers: Reduce future __run_timers() latency for first add to empty list

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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Reviewed-by: Oleg Nesterov <[email protected]>
Reviewed-by: Steven Rostedt <[email protected]>
Tested-by: Mike Galbraith <[email protected]>

0 files changed, 0 insertions, 0 deletions