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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-04-14 12:13:53 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-05-05 23:16:55 -0700
commit0f962a5e7277c34987b77dc82fc9aefcedc95e27 (patch)
treeb265d93dcc8f2669f8fb9b353344b9f6cc354728 /kernel/rcutree_plugin.h
parent27f4d28057adf98750cf863c40baefb12f5b6d21 (diff)
rcu: Force per-rcu_node kthreads off of the outgoing CPU
The scheduler has had some heartburn in the past when too many real-time kthreads were affinitied to the outgoing CPU. So, this commit lightens the load by forcing the per-rcu_node and the boost kthreads off of the outgoing CPU. Note that RCU's per-CPU kthread remains on the outgoing CPU until the bitter end, as it must in order to preserve correctness. Also avoid disabling hardirqs across calls to set_cpus_allowed_ptr(), given that this function can block. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree_plugin.h')
-rw-r--r--kernel/rcutree_plugin.h8
1 files changed, 5 insertions, 3 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 5964f82e2d9..4e486255df6 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1212,17 +1212,19 @@ static void rcu_initiate_boost(struct rcu_node *rnp)
}
}
+/*
+ * Set the affinity of the boost kthread. The CPU-hotplug locks are
+ * held, so no one should be messing with the existence of the boost
+ * kthread.
+ */
static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
cpumask_var_t cm)
{
- unsigned long flags;
struct task_struct *t;
- raw_spin_lock_irqsave(&rnp->lock, flags);
t = rnp->boost_kthread_task;
if (t != NULL)
set_cpus_allowed_ptr(rnp->boost_kthread_task, cm);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
#define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000)