timers: Reduce __run_timers() latency for 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.
In this case, which is likely to be common for NO_HZ_FULL kernels, the
kernel currently incurs a large latency for no good reason.  This commit
therefore short-circuits 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