rcu: Use softirq to address performance regression

[pandora-kernel.git] / kernel / rcutree.c

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 0a8ec5b..ae5c9ea 100644 (file)
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -100,6 +100,7 @@ static char rcu_kthreads_spawnable;
 
 static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu);
 static void invoke_rcu_cpu_kthread(void);
+static void __invoke_rcu_cpu_kthread(void);
 
 #define RCU_KTHREAD_PRIO 1     /* RT priority for per-CPU kthreads. */
 
@@ -1442,13 +1443,21 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
        }
 
        /* If there are callbacks ready, invoke them. */
-       rcu_do_batch(rsp, rdp);
+       if (cpu_has_callbacks_ready_to_invoke(rdp))
+               __invoke_rcu_cpu_kthread();
+}
+
+static void rcu_kthread_do_work(void)
+{
+       rcu_do_batch(&rcu_sched_state, &__get_cpu_var(rcu_sched_data));
+       rcu_do_batch(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
+       rcu_preempt_do_callbacks();
 }
 
 /*
  * Do softirq processing for the current CPU.
  */
-static void rcu_process_callbacks(void)
+static void rcu_process_callbacks(struct softirq_action *unused)
 {
        __rcu_process_callbacks(&rcu_sched_state,
                                &__get_cpu_var(rcu_sched_data));
@@ -1465,7 +1474,7 @@ static void rcu_process_callbacks(void)
  * the current CPU with interrupts disabled, the rcu_cpu_kthread_task
  * cannot disappear out from under us.
  */
-static void invoke_rcu_cpu_kthread(void)
+static void __invoke_rcu_cpu_kthread(void)
 {
        unsigned long flags;
 
@@ -1479,6 +1488,11 @@ static void invoke_rcu_cpu_kthread(void)
        local_irq_restore(flags);
 }
 
+static void invoke_rcu_cpu_kthread(void)
+{
+       raise_softirq(RCU_SOFTIRQ);
+}
+
 /*
  * Wake up the specified per-rcu_node-structure kthread.
  * Because the per-rcu_node kthreads are immortal, we don't need
@@ -1613,7 +1627,7 @@ static int rcu_cpu_kthread(void *arg)
                *workp = 0;
                local_irq_restore(flags);
                if (work)
-                       rcu_process_callbacks();
+                       rcu_kthread_do_work();
                local_bh_enable();
                if (*workp != 0)
                        spincnt++;
@@ -2387,6 +2401,7 @@ void __init rcu_init(void)
        rcu_init_one(&rcu_sched_state, &rcu_sched_data);
        rcu_init_one(&rcu_bh_state, &rcu_bh_data);
        __rcu_init_preempt();
+        open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
 
        /*
         * We don't need protection against CPU-hotplug here because