On Wed, Apr 14, 2010 at 03:51:50PM +0200, Peter Zijlstra wrote: > On Mon, 2010-04-12 at 20:43 -0700, Paul E. McKenney wrote: > > > So we might have to support the interrupt assumption, at least in some > > > form, with those guys... > > > > One way to make the interrupt assumption official is to use > > synchronize_sched() rather than synchronize_rcu(). > > Well, call_rcu_sched() then, because the current usage is to use > call_rcu() to free the page directories. > > Paul, here is a call_rcu_sched() available in kernel/rcutree.c, but am I > right in reading that code that that would not be available for > preemptible RCU? Both call_rcu_sched() and call_rcu() are always there for you. ;-) o If CONFIG_TREE_RCU (or CONFIG_TINY_RCU), they both have the same implementation. o If CONFIG_TREE_PREEMPT_RCU, call_rcu_sched() is preemptible and call_rcu() is not. Of course, with call_rcu_sched(), the corresponding RCU read-side critical sections are non-preemptible. Therefore, in CONFIG_PREEMPT_RT, these read-side critical sections must use raw spinlocks. Can the code in question accommodate these restrictions? Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
