Commit-ID: 67abb96cbf307e16e3c6d1a0328ece085b5ce94c
Gitweb: https://git.kernel.org/tip/67abb96cbf307e16e3c6d1a0328ece085b5ce94c
Author: Byungchul Park <byungchul.park@xxxxxxx>
AuthorDate: Fri, 1 Jun 2018 11:03:09 +0900
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 12 Jul 2018 15:39:22 -0700
rcu: Check the range of jiffies_till_{first,next}_fqs when setting them
Currently, the range of jiffies_till_{first,next}_fqs are checked and
adjusted on and on in the loop of rcu_gp_kthread on runtime.
However, it's enough to check them only when setting them, not every
time in the loop. So make them handled on a setting time via sysfs.
Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 45 ++++++++++++++++++++++++++++++++-------------
1 file changed, 32 insertions(+), 13 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 4915525559ac..7498a416f63b 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -510,8 +510,38 @@ static ulong jiffies_till_first_fqs = ULONG_MAX;
static ulong jiffies_till_next_fqs = ULONG_MAX;
static bool rcu_kick_kthreads;
-module_param(jiffies_till_first_fqs, ulong, 0644);
-module_param(jiffies_till_next_fqs, ulong, 0644);
+static int param_set_first_fqs_jiffies(const char *val, const struct kernel_param *kp)
+{
+ ulong j;
+ int ret = kstrtoul(val, 0, &j);
+
+ if (!ret)
+ WRITE_ONCE(*(ulong *)kp->arg, (j > HZ) ? HZ : j);
+ return ret;
+}
+
+static int param_set_next_fqs_jiffies(const char *val, const struct kernel_param *kp)
+{
+ ulong j;
+ int ret = kstrtoul(val, 0, &j);
+
+ if (!ret)
+ WRITE_ONCE(*(ulong *)kp->arg, (j > HZ) ? HZ : (j ?: 1));
+ return ret;
+}
+
+static struct kernel_param_ops first_fqs_jiffies_ops = {
+ .set = param_set_first_fqs_jiffies,
+ .get = param_get_ulong,
+};
+
+static struct kernel_param_ops next_fqs_jiffies_ops = {
+ .set = param_set_next_fqs_jiffies,
+ .get = param_get_ulong,
+};
+
+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(rcu_kick_kthreads, bool, 0644);
/*
@@ -2180,10 +2210,6 @@ static int __noreturn rcu_gp_kthread(void *arg)
/* Handle quiescent-state forcing. */
first_gp_fqs = true;
j = jiffies_till_first_fqs;
- if (j > HZ) {
- j = HZ;
- jiffies_till_first_fqs = HZ;
- }
ret = 0;
for (;;) {
if (!ret) {
@@ -2218,13 +2244,6 @@ static int __noreturn rcu_gp_kthread(void *arg)
WRITE_ONCE(rsp->gp_activity, jiffies);
ret = 0; /* Force full wait till next FQS. */
j = jiffies_till_next_fqs;
- if (j > HZ) {
- j = HZ;
- jiffies_till_next_fqs = HZ;
- } else if (j < 1) {
- j = 1;
- jiffies_till_next_fqs = 1;
- }
} else {
/* Deal with stray signal. */
cond_resched_tasks_rcu_qs();
--
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