From: Paul E. McKenney Date: Mon, 16 Dec 2013 13:57:10 +0000 (-0800) Subject: timers: Reduce __run_timers() latency for empty list X-Git-Tag: v3.15-rc1~153^2~28^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d550e81dc0ddc04f1b417c179c214103a28e0ee8;p=pandora-kernel.git 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 Reviewed-by: Josh Triplett Acked-by: Peter Zijlstra Reviewed-by: Oleg Nesterov Reviewed-by: Steven Rostedt Tested-by: Mike Galbraith --- Reading git-diff-tree failed