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* [PATCH] rcu: Make jiffies_till_sched_qs writable
@ 2019-07-08  6:00 Byungchul Park
  2019-07-08 12:50 ` Paul E. McKenney
  0 siblings, 1 reply; 53+ messages in thread
From: Byungchul Park @ 2019-07-08  6:00 UTC (permalink / raw)
  To: paulmck, josh, rostedt, mathieu.desnoyers, jiangshanlai, joel, rcu
  Cc: linux-kernel, kernel-team

jiffies_till_sched_qs is useless if it's readonly as it is used to set
jiffies_to_sched_qs with its value regardless of first/next fqs jiffies.
And it should be applied immediately on change through sysfs.

The function for setting jiffies_to_sched_qs,
adjust_jiffies_till_sched_qs() will be called only if
the value from sysfs != ULONG_MAX. And the value won't be adjusted
unlike first/next fqs jiffies.

While at it, changed the positions of two module_param()s downward.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
---
 kernel/rcu/tree.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a2f8ba2..a28e2fe 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -422,9 +422,7 @@ static int rcu_is_cpu_rrupt_from_idle(void)
  * quiescent-state help from rcu_note_context_switch().
  */
 static ulong jiffies_till_sched_qs = ULONG_MAX;
-module_param(jiffies_till_sched_qs, ulong, 0444);
 static ulong jiffies_to_sched_qs; /* See adjust_jiffies_till_sched_qs(). */
-module_param(jiffies_to_sched_qs, ulong, 0444); /* Display only! */
 
 /*
  * Make sure that we give the grace-period kthread time to detect any
@@ -450,6 +448,18 @@ static void adjust_jiffies_till_sched_qs(void)
 	WRITE_ONCE(jiffies_to_sched_qs, j);
 }
 
+static int param_set_sched_qs_jiffies(const char *val, const struct kernel_param *kp)
+{
+	ulong j;
+	int ret = kstrtoul(val, 0, &j);
+
+	if (!ret && j != ULONG_MAX) {
+		WRITE_ONCE(*(ulong *)kp->arg, j);
+		adjust_jiffies_till_sched_qs();
+	}
+	return ret;
+}
+
 static int param_set_first_fqs_jiffies(const char *val, const struct kernel_param *kp)
 {
 	ulong j;
@@ -474,6 +484,11 @@ static int param_set_next_fqs_jiffies(const char *val, const struct kernel_param
 	return ret;
 }
 
+static struct kernel_param_ops sched_qs_jiffies_ops = {
+	.set = param_set_sched_qs_jiffies,
+	.get = param_get_ulong,
+};
+
 static struct kernel_param_ops first_fqs_jiffies_ops = {
 	.set = param_set_first_fqs_jiffies,
 	.get = param_get_ulong,
@@ -484,8 +499,11 @@ static int param_set_next_fqs_jiffies(const char *val, const struct kernel_param
 	.get = param_get_ulong,
 };
 
+module_param_cb(jiffies_till_sched_qs, &sched_qs_jiffies_ops, &jiffies_till_sched_qs, 0644);
 module_param_cb(jiffies_till_first_fqs, &first_fqs_jiffies_ops, &jiffies_till_first_fqs, 0644);
 module_param_cb(jiffies_till_next_fqs, &next_fqs_jiffies_ops, &jiffies_till_next_fqs, 0644);
+
+module_param(jiffies_to_sched_qs, ulong, 0444); /* Display only! */
 module_param(rcu_kick_kthreads, bool, 0644);
 
 static void force_qs_rnp(int (*f)(struct rcu_data *rdp));
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 53+ messages in thread

end of thread, other threads:[~2019-07-24  8:00 UTC | newest]

Thread overview: 53+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-08  6:00 [PATCH] rcu: Make jiffies_till_sched_qs writable Byungchul Park
2019-07-08 12:50 ` Paul E. McKenney
2019-07-08 13:03   ` Joel Fernandes
2019-07-08 13:19     ` Paul E. McKenney
2019-07-08 14:15       ` Joel Fernandes
2019-07-09  6:05       ` Byungchul Park
2019-07-09 12:43         ` Paul E. McKenney
2019-07-09  5:58     ` Byungchul Park
2019-07-09  6:45       ` Byungchul Park
2019-07-09 12:41       ` Paul E. McKenney
2019-07-10  1:20         ` Byungchul Park
2019-07-11 12:30           ` Paul E. McKenney
2019-07-11 13:08             ` Joel Fernandes
2019-07-11 15:02               ` Paul E. McKenney
2019-07-11 16:48                 ` Joel Fernandes
2019-07-11 19:58                   ` Joel Fernandes
2019-07-12  6:32                     ` Byungchul Park
2019-07-12 12:51                       ` Joel Fernandes
2019-07-12 13:02                         ` Paul E. McKenney
2019-07-12 13:43                           ` Joel Fernandes
2019-07-12 14:53                             ` Paul E. McKenney
2019-07-13  8:47                         ` Byungchul Park
2019-07-13 14:20                           ` Joel Fernandes
2019-07-13 15:13                             ` Paul E. McKenney
2019-07-13 15:42                               ` Joel Fernandes
2019-07-13 17:41                                 ` Paul E. McKenney
2019-07-14 13:39                                   ` Byungchul Park
2019-07-14 13:56                                     ` Paul E. McKenney
2019-07-15 17:39                                       ` Joel Fernandes
2019-07-15 20:09                                         ` Paul E. McKenney
2019-07-18 16:14                                   ` Joel Fernandes
2019-07-18 16:15                                     ` Joel Fernandes
2019-07-18 21:34                                     ` Paul E. McKenney
2019-07-19  0:48                                       ` Joel Fernandes
2019-07-19  0:54                                       ` Byungchul Park
2019-07-19  0:39                                     ` Byungchul Park
2019-07-19  0:52                                       ` Joel Fernandes
2019-07-19  1:10                                         ` Byungchul Park
2019-07-19  7:43                                         ` Paul E. McKenney
2019-07-19  9:57                                           ` Byungchul Park
2019-07-19 19:57                                             ` Paul E. McKenney
2019-07-19 20:33                                               ` Joel Fernandes
2019-07-23 11:05                                                 ` Byungchul Park
2019-07-23 13:47                                                   ` Paul E. McKenney
2019-07-23 16:54                                                     ` Paul E. McKenney
2019-07-24  7:58                                                       ` Byungchul Park
2019-07-24  7:59                                                     ` Byungchul Park
2019-07-12 13:01                     ` Paul E. McKenney
2019-07-12 13:40                       ` Joel Fernandes
2019-07-12  6:00                 ` Byungchul Park
2019-07-12  5:52               ` Byungchul Park
2019-07-12  5:48             ` Byungchul Park
2019-07-13  9:08               ` Byungchul Park

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