From: Kevin Hilman khilman@linaro.org
Allow debugfs override of sched_tick_max_deferment in order to ease finding/fixing the remaining issues with full nohz.
The value to be written is in jiffies, and -1 means the max deferment is disabled (scheduler_tick_max_deferment() returns KTIME_MAX.)
Cc: Frederic Weisbecker fweisbec@gmail.com Signed-off-by: Kevin Hilman khilman@linaro.org --- kernel/sched/core.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index bc1638b33449..dee044a5d447 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2514,6 +2514,8 @@ void scheduler_tick(void) }
#ifdef CONFIG_NO_HZ_FULL +static u32 sched_tick_max_deferment = HZ; + /** * scheduler_tick_max_deferment * @@ -2532,13 +2534,25 @@ u64 scheduler_tick_max_deferment(void) struct rq *rq = this_rq(); unsigned long next, now = ACCESS_ONCE(jiffies);
- next = rq->last_sched_tick + HZ; + if (sched_tick_max_deferment == -1) + return KTIME_MAX; + + next = rq->last_sched_tick + sched_tick_max_deferment;
if (time_before_eq(next, now)) return 0;
return jiffies_to_nsecs(next - now); } + +static __init int sched_nohz_full_init_debug(void) +{ + debugfs_create_u32("sched_tick_max_deferment", 0644, NULL, + &sched_tick_max_deferment); + + return 0; +} +late_initcall(sched_nohz_full_init_debug); #endif
notrace unsigned long get_parent_ip(unsigned long addr)