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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2008-01-25 21:08:24 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-25 21:08:24 +0100
commite260be673a15b6125068270e0216a3bfbfc12f87 (patch)
treef50760606d395bf6faa9e865f814761a3c88d32c /include/linux/rcupdate.h
parente0ecfa7917cafe72f4a75f87e8bb5d8d51dc534f (diff)
Preempt-RCU: implementation
This patch implements a new version of RCU which allows its read-side critical sections to be preempted. It uses a set of counter pairs to keep track of the read-side critical sections and flips them when all tasks exit read-side critical section. The details of this implementation can be found in this paper - http://www.rdrop.com/users/paulmck/RCU/OLSrtRCU.2006.08.11a.pdf and the article- http://lwn.net/Articles/253651/ This patch was developed as a part of the -rt kernel development and meant to provide better latencies when read-side critical sections of RCU don't disable preemption. As a consequence of keeping track of RCU readers, the readers have a slight overhead (optimizations in the paper). This implementation co-exists with the "classic" RCU implementations and can be switched to at compiler. Also includes RCU tracing summarized in debugfs. [ akpm@linux-foundation.org: build fixes on non-preempt architectures ] Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com> Reviewed-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/rcupdate.h')
-rw-r--r--include/linux/rcupdate.h11
1 files changed, 7 insertions, 4 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 12aa13e1315..d32c14de270 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -53,7 +53,11 @@ struct rcu_head {
void (*func)(struct rcu_head *head);
};
+#ifdef CONFIG_CLASSIC_RCU
#include <linux/rcuclassic.h>
+#else /* #ifdef CONFIG_CLASSIC_RCU */
+#include <linux/rcupreempt.h>
+#endif /* #else #ifdef CONFIG_CLASSIC_RCU */
#define RCU_HEAD_INIT { .next = NULL, .func = NULL }
#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT
@@ -231,13 +235,12 @@ extern void call_rcu_bh(struct rcu_head *head,
/* Exported common interfaces */
extern void synchronize_rcu(void);
extern void rcu_barrier(void);
+extern long rcu_batches_completed(void);
+extern long rcu_batches_completed_bh(void);
/* Internal to kernel */
extern void rcu_init(void);
-extern void rcu_check_callbacks(int cpu, int user);
-
-extern long rcu_batches_completed(void);
-extern long rcu_batches_completed_bh(void);
+extern int rcu_needs_cpu(int cpu);
#endif /* __KERNEL__ */
#endif /* __LINUX_RCUPDATE_H */