1 files changed, 61 insertions, 0 deletions

diff --git a/recipes-kernel/linux/files/patches/sched-nohz-add-debugfs-control-over-sched_tick_max_d.patch b/recipes-kernel/linux/files/patches/sched-nohz-add-debugfs-control-over-sched_tick_max_d.patch
new file mode 100644
index 0000000..349604c
--- /dev/null
+++ b/recipes-kernel/linux/files/patches/sched-nohz-add-debugfs-control-over-sched_tick_max_d.patch
@@ -0,0 +1,61 @@
+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
+