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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-03-27 08:44:00 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-06-10 13:45:49 -0700
commit127781d1ba1ee5bbe1780afa35dd0e71583b143d (patch)
tree3c9b5961bc02e7f380a7bd7932181329ecbec397 /include/linux
parentefc151c33b971148894789dc7c5589dec46d4348 (diff)
rcu: Remove TINY_PREEMPT_RCU
TINY_PREEMPT_RCU adds significant code and complexity, but does not offer commensurate benefits. People currently using TINY_PREEMPT_RCU can get much better memory footprint with TINY_RCU, or, if they really need preemptible RCU, they can use TREE_PREEMPT_RCU with a relatively minor degradation in memory footprint. Please note that this move has been widely publicized on LKML (https://lkml.org/lkml/2012/11/12/545) and on LWN (http://lwn.net/Articles/541037/). This commit therefore removes TINY_PREEMPT_RCU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Updated to eliminate #else in rcutiny.h as suggested by Josh ] Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/hardirq.h2
-rw-r--r--include/linux/rcupdate.h2
-rw-r--r--include/linux/rcutiny.h24
3 files changed, 4 insertions, 24 deletions
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index c1d6555d2567..05bcc0903766 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -128,7 +128,7 @@ extern void synchronize_irq(unsigned int irq);
# define synchronize_irq(irq) barrier()
#endif
-#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
+#if defined(CONFIG_TINY_RCU)
static inline void rcu_nmi_enter(void)
{
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index ddcc7826d907..70b1522badd3 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -277,7 +277,7 @@ void wait_rcu_gp(call_rcu_func_t crf);
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
#include <linux/rcutree.h>
-#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
+#elif defined(CONFIG_TINY_RCU)
#include <linux/rcutiny.h>
#else
#error "Unknown RCU implementation specified to kernel configuration"
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 4e56a9c69a35..d3c094ffa960 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -53,16 +53,7 @@ static inline void rcu_barrier(void)
rcu_barrier_sched(); /* Only one CPU, so only one list of callbacks! */
}
-#else /* #ifdef CONFIG_TINY_RCU */
-
-void synchronize_rcu_expedited(void);
-
-static inline void rcu_barrier(void)
-{
- wait_rcu_gp(call_rcu);
-}
-
-#endif /* #else #ifdef CONFIG_TINY_RCU */
+#endif /* #ifdef CONFIG_TINY_RCU */
static inline void synchronize_rcu_bh(void)
{
@@ -97,18 +88,7 @@ static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
return 0;
}
-#else /* #ifdef CONFIG_TINY_RCU */
-
-void rcu_preempt_note_context_switch(void);
-int rcu_preempt_needs_cpu(void);
-
-static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
-{
- *delta_jiffies = ULONG_MAX;
- return rcu_preempt_needs_cpu();
-}
-
-#endif /* #else #ifdef CONFIG_TINY_RCU */
+#endif /* #ifdef CONFIG_TINY_RCU */
static inline void rcu_note_context_switch(int cpu)
{