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From 92f0d4f695198fcb935cf0360f93a15bf0a6af1e Mon Sep 17 00:00:00 2001
From: Kevin Hilman <khilman@linaro.org>
Date: Mon, 16 Sep 2013 15:43:48 -0700
Subject: [PATCH 3/3] sched/nohz: add debugfs control over
sched_tick_max_deferment
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 e8b3350..59c7367 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2753,6 +2753,8 @@ void scheduler_tick(void)
}
#ifdef CONFIG_NO_HZ_FULL
+static u32 sched_tick_max_deferment = HZ;
+
/**
* scheduler_tick_max_deferment
*
@@ -2769,13 +2771,25 @@ 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_usecs(next - now) * NSEC_PER_USEC;
}
+
+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)
--
1.7.10.4
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