2 files changed, 26 insertions, 7 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 1009c0ccd4b1..f344d3c824a4 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -218,8 +218,8 @@ module_param(blimit, long, 0444);
 module_param(qhimark, long, 0444);
 module_param(qlowmark, long, 0444);
 
-static ulong jiffies_till_first_fqs = RCU_JIFFIES_TILL_FORCE_QS;
-static ulong jiffies_till_next_fqs = RCU_JIFFIES_TILL_FORCE_QS;
+static ulong jiffies_till_first_fqs = ULONG_MAX;
+static ulong jiffies_till_next_fqs = ULONG_MAX;
 
 module_param(jiffies_till_first_fqs, ulong, 0644);
 module_param(jiffies_till_next_fqs, ulong, 0644);
@@ -3265,11 +3265,25 @@ static void __init rcu_init_one(struct rcu_state *rsp,
  */
 static void __init rcu_init_geometry(void)
 {
+        ulong d;
         int i;
         int j;
         int n = nr_cpu_ids;
         int rcu_capacity[MAX_RCU_LVLS + 1];
 
+        /*
+         * Initialize any unspecified boot parameters.
+         * The default values of jiffies_till_first_fqs and
+         * jiffies_till_next_fqs are set to the RCU_JIFFIES_TILL_FORCE_QS
+         * value, which is a function of HZ, then adding one for each
+         * RCU_JIFFIES_FQS_DIV CPUs that might be on the system.
+         */
+        d = RCU_JIFFIES_TILL_FORCE_QS + nr_cpu_ids / RCU_JIFFIES_FQS_DIV;
+        if (jiffies_till_first_fqs == ULONG_MAX)
+                jiffies_till_first_fqs = d;
+        if (jiffies_till_next_fqs == ULONG_MAX)
+                jiffies_till_next_fqs = d;
+
         /* If the compile-time values are accurate, just leave. */
         if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF &&
             nr_cpu_ids == NR_CPUS)
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 4df503470e42..4a39d364493c 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -343,12 +343,17 @@ struct rcu_data {
 #define RCU_FORCE_QS            3       /* Need to force quiescent state. */
 #define RCU_SIGNAL_INIT         RCU_SAVE_DYNTICK
 
-#define RCU_JIFFIES_TILL_FORCE_QS        3      /* for rsp->jiffies_force_qs */
+#define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
+                                        /* For jiffies_till_first_fqs and */
+                                        /*  and jiffies_till_next_fqs. */
 
-#define RCU_STALL_RAT_DELAY             2       /* Allow other CPUs time */
-                                                /*  to take at least one */
-                                                /*  scheduling clock irq */
-                                                /*  before ratting on them. */
+#define RCU_JIFFIES_FQS_DIV     256     /* Very large systems need more */
+                                        /*  delay between bouts of */
+                                        /*  quiescent-state forcing. */
+
+#define RCU_STALL_RAT_DELAY     2       /* Allow other CPUs time to take */
+                                        /*  at least one scheduling clock */
+                                        /*  irq before ratting on them. */
 
 #define rcu_wait(cond)                                                  \
 do {                                                                    \