From 20e9751bd9dd6b832fd84ada27840360f7e877f1 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 4 Oct 2006 02:17:17 -0700 Subject: [PATCH] rcu: simplify/improve batch tuning Kill a hard-to-calculate 'rsinterval' boot parameter and per-cpu rcu_data.last_rs_qlen. Instead, it adds adds a flag rcu_ctrlblk.signaled, which records the fact that one of CPUs has sent a resched IPI since the last rcu_start_batch(). Roughly speaking, we need two rcu_start_batch()s in order to move callbacks from ->nxtlist to ->donelist. This means that when ->qlen exceeds qhimark and continues to grow, we should send a resched IPI, and then do it again after we gone through a quiescent state. On the other hand, if it was already sent, we don't need to do it again when another CPU detects overflow of the queue. Signed-off-by: Oleg Nesterov Acked-by: Paul E. McKenney Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/rcupdate.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index b4ca73d6589..f6dd71bf8a4 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -66,6 +66,8 @@ struct rcu_ctrlblk { long completed; /* Number of the last completed batch */ int next_pending; /* Is the next batch already waiting? */ + int signaled; + spinlock_t lock ____cacheline_internodealigned_in_smp; cpumask_t cpumask; /* CPUs that need to switch in order */ /* for current batch to proceed. */ @@ -106,9 +108,6 @@ struct rcu_data { long blimit; /* Upper limit on a processed batch */ int cpu; struct rcu_head barrier; -#ifdef CONFIG_SMP - long last_rs_qlen; /* qlen during the last resched */ -#endif }; DECLARE_PER_CPU(struct rcu_data, rcu_data); -- cgit v1.2.3