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@@ -534,8 +534,8 @@ module_param(rcu_kick_kthreads, bool, 0644);
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* How long the grace period must be before we start recruiting
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* quiescent-state help from rcu_note_context_switch().
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*/
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-static ulong jiffies_till_sched_qs = HZ / 20;
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-module_param(jiffies_till_sched_qs, ulong, 0644);
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+static ulong jiffies_till_sched_qs = HZ / 10;
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+module_param(jiffies_till_sched_qs, ulong, 0444);
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static bool rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
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struct rcu_data *rdp);
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@@ -1235,7 +1235,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
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unsigned long jtsq;
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bool *rnhqp;
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bool *ruqp;
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- unsigned long rjtsc;
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struct rcu_node *rnp;
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/*
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@@ -1252,23 +1251,13 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
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return 1;
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}
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- /* Compute and saturate jiffies_till_sched_qs. */
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- jtsq = jiffies_till_sched_qs;
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- rjtsc = rcu_jiffies_till_stall_check();
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- if (jtsq > rjtsc / 2) {
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- WRITE_ONCE(jiffies_till_sched_qs, rjtsc);
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- jtsq = rjtsc / 2;
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- } else if (jtsq < 1) {
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- WRITE_ONCE(jiffies_till_sched_qs, 1);
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- jtsq = 1;
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- }
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-
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/*
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* Has this CPU encountered a cond_resched_rcu_qs() since the
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* beginning of the grace period? For this to be the case,
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* the CPU has to have noticed the current grace period. This
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* might not be the case for nohz_full CPUs looping in the kernel.
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*/
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+ jtsq = jiffies_till_sched_qs;
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rnp = rdp->mynode;
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ruqp = per_cpu_ptr(&rcu_dynticks.rcu_urgent_qs, rdp->cpu);
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if (time_after(jiffies, rdp->rsp->gp_start + jtsq) &&
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@@ -1276,7 +1265,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
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READ_ONCE(rdp->gpnum) == rnp->gpnum && !rdp->gpwrap) {
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trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("rqc"));
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return 1;
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- } else {
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+ } else if (time_after(jiffies, rdp->rsp->gp_start + jtsq)) {
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/* Load rcu_qs_ctr before store to rcu_urgent_qs. */
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smp_store_release(ruqp, true);
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}
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@@ -1304,10 +1293,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
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* updates are only once every few jiffies, the probability of
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* lossage (and thus of slight grace-period extension) is
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* quite low.
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- *
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- * Note that if the jiffies_till_sched_qs boot/sysfs parameter
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- * is set too high, we override with half of the RCU CPU stall
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- * warning delay.
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*/
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rnhqp = &per_cpu(rcu_dynticks.rcu_need_heavy_qs, rdp->cpu);
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if (!READ_ONCE(*rnhqp) &&
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@@ -1316,7 +1301,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
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WRITE_ONCE(*rnhqp, true);
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/* Store rcu_need_heavy_qs before rcu_urgent_qs. */
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smp_store_release(ruqp, true);
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- rdp->rsp->jiffies_resched += 5; /* Re-enable beating. */
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+ rdp->rsp->jiffies_resched += jtsq; /* Re-enable beating. */
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}
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/*
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