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Add TinyRCU

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1 parent 17ed946 commit d6666676181aba8c13d33f487583e475efe6c095 @psyke83 committed Sep 18, 2011
Showing with 435 additions and 0 deletions.
  1. +24 −0 include/linux/hardirq.h
  2. +6 −0 include/linux/rcupdate.h
  3. +97 −0 include/linux/rcutiny.h
  4. +9 −0 init/Kconfig
  5. +1 −0 kernel/Makefile
  6. +4 −0 kernel/rcupdate.c
  7. +294 −0 kernel/rcutiny.c
@@ -139,10 +139,34 @@ static inline void account_system_vtime(struct task_struct *tsk)
#endif
#if defined(CONFIG_NO_HZ)
+#if defined(CONFIG_TINY_RCU)
+extern void rcu_enter_nohz(void);
+extern void rcu_exit_nohz(void);
+
+static inline void rcu_irq_enter(void)
+{
+ rcu_exit_nohz();
+}
+
+static inline void rcu_irq_exit(void)
+{
+ rcu_enter_nohz();
+}
+
+static inline void rcu_nmi_enter(void)
+{
+}
+
+static inline void rcu_nmi_exit(void)
+{
+}
+
+#else
extern void rcu_irq_enter(void);
extern void rcu_irq_exit(void);
extern void rcu_nmi_enter(void);
extern void rcu_nmi_exit(void);
+#endif
#else
# define rcu_irq_enter() do { } while (0)
# define rcu_irq_exit() do { } while (0)
@@ -68,11 +68,17 @@ extern int sched_expedited_torture_stats(char *page);
/* Internal to kernel */
extern void rcu_init(void);
extern void rcu_scheduler_starting(void);
+#ifndef CONFIG_TINY_RCU
extern int rcu_needs_cpu(int cpu);
+#else
+static inline int rcu_needs_cpu(int cpu) { return 0; }
+#endif
extern int rcu_scheduler_active;
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
#include <linux/rcutree.h>
+#elif CONFIG_TINY_RCU
+#include <linux/rcutiny.h>
#else
#error "Unknown RCU implementation specified to kernel configuration"
#endif
@@ -0,0 +1,97 @@
+/*
+ * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright IBM Corporation, 2008
+ *
+ * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ *
+ * For detailed explanation of Read-Copy Update mechanism see -
+ * Documentation/RCU
+ */
+
+#ifndef __LINUX_TINY_H
+#define __LINUX_TINY_H
+
+#include <linux/cache.h>
+
+void rcu_sched_qs(int cpu);
+void rcu_bh_qs(int cpu);
+
+#define __rcu_read_lock() preempt_disable()
+#define __rcu_read_unlock() preempt_enable()
+#define __rcu_read_lock_bh() local_bh_disable()
+#define __rcu_read_unlock_bh() local_bh_enable()
+#define call_rcu_sched call_rcu
+
+#define rcu_init_sched() do { } while (0)
+extern void rcu_check_callbacks(int cpu, int user);
+extern void __rcu_init(void);
+
+/*
+ * Return the number of grace periods.
+ */
+static inline long rcu_batches_completed(void)
+{
+ return 0;
+}
+
+/*
+ * Return the number of bottom-half grace periods.
+ */
+static inline long rcu_batches_completed_bh(void)
+{
+ return 0;
+}
+
+extern int rcu_expedited_torture_stats(char *page);
+
+static inline void synchronize_rcu_expedited(void)
+{
+ synchronize_sched();
+}
+
+static inline void synchronize_rcu_bh_expedited(void)
+{
+ synchronize_sched();
+}
+
+struct notifier_block;
+extern int rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu);
+
+#ifdef CONFIG_NO_HZ
+
+extern void rcu_enter_nohz(void);
+extern void rcu_exit_nohz(void);
+
+#else /* #ifdef CONFIG_NO_HZ */
+
+static inline void rcu_enter_nohz(void)
+{
+}
+
+static inline void rcu_exit_nohz(void)
+{
+}
+
+#endif /* #else #ifdef CONFIG_NO_HZ */
+
+static inline void exit_rcu(void)
+{
+}
+
+#endif /* __LINUX_RCUTINY_H */
View
@@ -334,6 +334,15 @@ config TREE_PREEMPT_RCU
is also required. It also scales down nicely to
smaller systems.
+config TINY_RCU
+ bool "UP-only small-memory-footprint RCU"
+ depends on !SMP
+ help
+ This option selects the RCU implementation that is
+ designed for UP systems from which real-time response
+ is not required. This option greatly reduces the
+ memory footprint of RCU.
+
endchoice
config RCU_TRACE
View
@@ -82,6 +82,7 @@ obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
obj-$(CONFIG_TREE_RCU) += rcutree.o
obj-$(CONFIG_TREE_PREEMPT_RCU) += rcutree.o
obj-$(CONFIG_TREE_RCU_TRACE) += rcutree_trace.o
+obj-$(CONFIG_TINY_RCU) += rcutiny.o
obj-$(CONFIG_RELAY) += relay.o
obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
View
@@ -67,6 +67,8 @@ void wakeme_after_rcu(struct rcu_head *head)
complete(&rcu->completion);
}
+#ifndef CONFIG_TINY_RCU
+
#ifdef CONFIG_TREE_PREEMPT_RCU
/**
@@ -157,6 +159,8 @@ void synchronize_rcu_bh(void)
}
EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
+#endif /* #ifndef CONFIG_TINY_RCU */
+
static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
unsigned long action, void *hcpu)
{
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