A new interface call_rcu_rt() allows the updates to happen immediately
in a UP kernel. This assumes that no RCU protection is needed 
against interrupts.


 include/linux/rcupdate.h |   14 ++++++++++++++
 1 files changed, 14 insertions(+)

diff -puN include/linux/rcupdate.h~rcu-rt-latency include/linux/rcupdate.h
--- linux-2.6.0-test8-rcu/include/linux/rcupdate.h~rcu-rt-latency	2003-11-30 19:54:09.000000000 +0530
+++ linux-2.6.0-test8-rcu-dipankar/include/linux/rcupdate.h	2003-11-30 21:39:50.000000000 +0530
@@ -131,6 +131,20 @@ extern void rcu_check_callbacks(int cpu,
 extern void FASTCALL(call_rcu(struct rcu_head *head, 
                           void (*func)(void *arg), void *arg));
 extern void synchronize_kernel(void);
+#if !defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
+static inline void call_rcu_rt(struct rcu_head *head, 
+                          void (*func)(void *arg), void *arg)
+{
+	func(arg);
+}
+#else
+static inline void call_rcu_rt(struct rcu_head *head, 
+                          void (*func)(void *arg), void *arg)
+{
+	call_rcu(head, func, arg);
+}
+#endif
+
 
 #endif /* __KERNEL__ */
 #endif /* __LINUX_RCUPDATE_H */

_