Commit-ID: c310ce4dcb9df9b2f1be82caff7dae609fe53f72 Gitweb: https://git.kernel.org/tip/c310ce4dcb9df9b2f1be82caff7dae609fe53f72 Author: Zhenzhong Duan <zhenzhong.d...@oracle.com> AuthorDate: Sun, 8 Oct 2017 20:55:59 -0700 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Wed, 18 Oct 2017 15:29:33 +0200
timers: Avoid an unnecessary iteration in __run_timers() If the base clock is behind jiffies in the soft irq expiry code then the next timer is retrieved by get_next_timer_interrupt() to avoid incrementing base clock one by one. If the next timer interrupt is past current jiffies then the base clock is set to jiffies - 1. At the call site this is incremented and another iteration through the expiry loop is executed which checks empty hash buckets. That's a pointless excercise because it's already known that the next timer is past jiffies. Set the base clock in that case to jiffies directly so it gets incremented to jiffies + 1 at the call site resulting in immediate termination of the expiry loop. [ tglx: Massaged changelog and added comment to the code ] Signed-off-by: Zhenzhong Duan <zhenzhong.d...@oracle.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Acked-by: Anna-Maria Gleixner <anna-ma...@linutronix.de> Cc: Joe Jin <joe....@oracle.com> Cc: sb...@codeaurora.org Cc: Srinivas Reddy Eeda <srinivas.e...@oracle.com> Cc: john.stu...@linaro.org Link: https://lkml.kernel.org/r/7086a857-f90c-4616-bbe8-f7696f21626c@default --- kernel/time/timer.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 38613ce..ee1a88d 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1560,8 +1560,11 @@ static int collect_expired_timers(struct timer_base *base, * jiffies, otherwise forward to the next expiry time: */ if (time_after(next, jiffies)) { - /* The call site will increment clock! */ - base->clk = jiffies - 1; + /* + * The call site will increment base->clk and then + * terminate the expiry loop immediately. + */ + base->clk = jiffies; return 0; } base->clk = next;
