Messages in this thread | | | Date | Sat, 2 Jun 2018 04:45:22 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] rcu: Check the range of jiffies_till_{first,next}_fqs when setting them |
| |
On Fri, Jun 01, 2018 at 11:03:09AM +0900, Byungchul Park wrote: > 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>
Applied for further review and testing, thank you!
Thanx, Paul
> --- > 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 >
| |