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-rw-r--r--kernel/rcu/tree.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 3e89b5b83ea0..71395e91b876 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -56,6 +56,7 @@
#include <linux/smpboot.h>
#include <linux/jiffies.h>
#include <linux/sched/isolation.h>
+#include <linux/sched/clock.h>
#include "../time/tick-internal.h"
#include "tree.h"
@@ -416,6 +417,12 @@ module_param(qlowmark, long, 0444);
static ulong jiffies_till_first_fqs = ULONG_MAX;
static ulong jiffies_till_next_fqs = ULONG_MAX;
static bool rcu_kick_kthreads;
+static int rcu_divisor = 7;
+module_param(rcu_divisor, int, 0644);
+
+/* Force an exit from rcu_do_batch() after 3 milliseconds. */
+static long rcu_resched_ns = 3 * NSEC_PER_MSEC;
+module_param(rcu_resched_ns, long, 0644);
/*
* How long the grace period must be before we start recruiting
@@ -2109,6 +2116,7 @@ static void rcu_do_batch(struct rcu_data *rdp)
struct rcu_head *rhp;
struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
long bl, count;
+ long pending, tlimit = 0;
/* If no callbacks are ready, just return. */
if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
@@ -2130,7 +2138,10 @@ static void rcu_do_batch(struct rcu_data *rdp)
local_irq_save(flags);
rcu_nocb_lock(rdp);
WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
- bl = rdp->blimit;
+ pending = rcu_segcblist_n_cbs(&rdp->cblist);
+ bl = max(rdp->blimit, pending >> rcu_divisor);
+ if (unlikely(bl > 100))
+ tlimit = local_clock() + rcu_resched_ns;
trace_rcu_batch_start(rcu_state.name,
rcu_segcblist_n_lazy_cbs(&rdp->cblist),
rcu_segcblist_n_cbs(&rdp->cblist), bl);
@@ -2153,6 +2164,13 @@ static void rcu_do_batch(struct rcu_data *rdp)
(need_resched() ||
(!is_idle_task(current) && !rcu_is_callbacks_kthread())))
break;
+ if (unlikely(tlimit)) {
+ /* only call local_clock() every 32 callbacks */
+ if (likely((-rcl.len & 31) || local_clock() < tlimit))
+ continue;
+ /* Exceeded the time limit, so leave. */
+ break;
+ }
if (offloaded) {
WARN_ON_ONCE(in_serving_softirq());
local_bh_enable();