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author | Zhenzhong Duan <zhenzhong.duan@oracle.com> | 2017-10-08 20:55:59 -0700 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2017-10-18 15:29:33 +0200 |
commit | c310ce4dcb9df9b2f1be82caff7dae609fe53f72 (patch) | |
tree | 8fa396c14f6322c0c1eec01b7abd28f4cf25d6fc /kernel | |
parent | b93ab338f7f0e39321b282d694a52736fdab172b (diff) | |
download | linux-stable-c310ce4dcb9df9b2f1be82caff7dae609fe53f72.tar.gz linux-stable-c310ce4dcb9df9b2f1be82caff7dae609fe53f72.tar.bz2 linux-stable-c310ce4dcb9df9b2f1be82caff7dae609fe53f72.zip |
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.duan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Joe Jin <joe.jin@oracle.com>
Cc: sboyd@codeaurora.org
Cc: Srinivas Reddy Eeda <srinivas.eeda@oracle.com>
Cc: john.stultz@linaro.org
Link: https://lkml.kernel.org/r/7086a857-f90c-4616-bbe8-f7696f21626c@default
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/time/timer.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 38613ced2324..ee1a88d8afb2 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; |