Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 09/14] rcu: Don't initiate RCU priority boosting on root rcu_node | Date | Wed, 7 Jan 2015 09:32:28 -0800 |
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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Because there is no longer any preempted tasks on the root rcu_node, and because there is no longer ever an rcub kthread for the root rcu_node, this commit drops the code in force_qs_rnp() that attempts to awaken the non-existent root rcub kthread. This is strictly a performance enhancement, removing a root rcu_node ->lock acquisition and release along with some tests in rcu_initiate_boost(), ending with the test that notes that there is no rcub kthread.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- kernel/rcu/tree.c | 6 ------ 1 file changed, 6 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 990b406faf4e..5a0a4c969d38 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2513,12 +2513,6 @@ static void force_qs_rnp(struct rcu_state *rsp, } raw_spin_unlock_irqrestore(&rnp->lock, flags); } - rnp = rcu_get_root(rsp); - if (rnp->qsmask == 0) { - raw_spin_lock_irqsave(&rnp->lock, flags); - smp_mb__after_unlock_lock(); - rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ - } } /* -- 1.8.1.5
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