From: Byungchul Park <byungchul.park@lge.com>
To: jiangshanlai@gmail.com, paulmck@linux.vnet.ibm.com,
josh@joshtriplett.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com
Cc: linux-kernel@vger.kernel.org, kernel-team@lge.com,
joel@joelfernandes.org
Subject: [PATCH] rcu: Check the range of jiffies_till_{first,next}_fqs when setting them
Date: Fri, 1 Jun 2018 11:03:09 +0900 [thread overview]
Message-ID: <1527818589-13476-1-git-send-email-byungchul.park@lge.com> (raw)
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@lge.com>
---
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 4e96761..eb54d7d 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -518,8 +518,38 @@ void rcu_all_qs(void)
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);
/*
@@ -2129,10 +2159,6 @@ 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) {
@@ -2167,13 +2193,6 @@ 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();
--
1.9.1
next reply other threads:[~2018-06-01 2:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-01 2:03 Byungchul Park [this message]
2018-06-02 11:45 ` [PATCH] rcu: Check the range of jiffies_till_{first,next}_fqs when setting them Paul E. McKenney
2018-06-03 3:58 ` Joel Fernandes
2018-06-03 5:38 ` Byungchul Park
2018-06-03 6:23 ` Joel Fernandes
2018-06-03 7:51 ` Byungchul Park
2018-06-03 18:47 ` Joel Fernandes
2018-06-04 0:30 ` Byungchul Park
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