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Message-ID: <20081223220648.GB16472@linux.vnet.ibm.com>
Date: Tue, 23 Dec 2008 14:06:48 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...e.hu, tglx@...utronix.de, akpm@...ux-foundation.org,
ralf@...ux-mips.org, kernel@...tstofly.org, hskinnemoen@...el.com,
cooloney@...nel.org, tony.luck@...el.com, geert@...ux-m68k.org,
zippel@...ux-m68k.org, jwboyer@...ux.vnet.ibm.com,
mporter@...nel.crashing.org, grant.likely@...retlab.ca,
paulus@...ba.org, benh@...nel.crashing.org, dhowells@...hat.com,
yasutake.koichi@...panasonic.com, lethal@...ux-sh.org,
hpa@...or.com
Subject: [PATCH, -tip] Make hierarchical RCU be the default
This patch makes the new TREE_RCU be the default, pointing the old
CLASSIC_RCU Kconfig symbol at it and introducing a new FLAT_RCU symbol
to allow the old version to be selected.
This patch is -not- yet suitable for inclusion, only for testing in
-tip, -next, and the like.
Suggested-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
include/linux/hardirq.h | 4 ++--
include/linux/pagemap.h | 4 ++--
include/linux/rcupdate.h | 4 ++--
kernel/Kconfig.preempt | 19 +++++++++++++++----
kernel/Makefile | 2 +-
lib/Kconfig.debug | 2 +-
6 files changed, 23 insertions(+), 12 deletions(-)
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 9b70b92..0afd180 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -118,7 +118,7 @@ static inline void account_system_vtime(struct task_struct *tsk)
}
#endif
-#if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU)
+#if defined(CONFIG_NO_HZ) && !defined(CONFIG_FLAT_RCU)
extern void rcu_irq_enter(void);
extern void rcu_irq_exit(void);
extern void rcu_nmi_enter(void);
@@ -128,7 +128,7 @@ extern void rcu_nmi_exit(void);
# define rcu_irq_exit() do { } while (0)
# define rcu_nmi_enter() do { } while (0)
# define rcu_nmi_exit() do { } while (0)
-#endif /* #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU) */
+#endif /* #if defined(CONFIG_NO_HZ) && !defined(CONFIG_FLAT_RCU) */
/*
* It is safe to do non-atomic ops on ->hardirq_context,
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 709742b..5cfb133 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -140,7 +140,7 @@ static inline int page_cache_get_speculative(struct page *page)
{
VM_BUG_ON(in_interrupt());
-#if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU)
+#if !defined(CONFIG_SMP) && defined(CONFIG_FLAT_RCU)
# ifdef CONFIG_PREEMPT
VM_BUG_ON(!in_atomic());
# endif
@@ -178,7 +178,7 @@ static inline int page_cache_add_speculative(struct page *page, int count)
{
VM_BUG_ON(in_interrupt());
-#if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU)
+#if !defined(CONFIG_SMP) && defined(CONFIG_FLAT_RCU)
# ifdef CONFIG_PREEMPT
VM_BUG_ON(!in_atomic());
# endif
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index bfd289a..819bf83 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -52,7 +52,7 @@ struct rcu_head {
void (*func)(struct rcu_head *head);
};
-#if defined(CONFIG_CLASSIC_RCU)
+#if defined(CONFIG_FLAT_RCU)
#include <linux/rcuclassic.h>
#elif defined(CONFIG_TREE_RCU)
#include <linux/rcutree.h>
@@ -60,7 +60,7 @@ struct rcu_head {
#include <linux/rcupreempt.h>
#else
#error "Unknown RCU implementation specified to kernel configuration"
-#endif /* #else #if defined(CONFIG_CLASSIC_RCU) */
+#endif /* #else #if defined(CONFIG_FLAT_RCU) */
#define RCU_HEAD_INIT { .next = NULL, .func = NULL }
#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 463f297..417a76b 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -52,16 +52,27 @@ config PREEMPT
endchoice
+config CLASSIC_RCU
+ bool "Select default RCU implementation"
+ select TREE_RCU
+ help
+ This option provides backwards compatibility for old defconfig
+ files that used CLASSIC_RCU.
+
+ Say Y if you are unsure.
+
choice
prompt "RCU Implementation"
- default CLASSIC_RCU
+ default TREE_RCU
-config CLASSIC_RCU
- bool "Classic RCU"
+config FLAT_RCU
+ bool "Flat (AKA classic) RCU"
help
This option selects the classic RCU implementation that is
designed for best read-side performance on non-realtime
- systems.
+ systems with modest numbers of CPUs. Its flat bit-map
+ implementation makes it unsuitable for systems with hundreds
+ or thousands of CPUs.
Select this option if you are unsure.
diff --git a/kernel/Makefile b/kernel/Makefile
index b4fdbbf..73e9a94 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -73,7 +73,7 @@ obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o
obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
obj-$(CONFIG_SECCOMP) += seccomp.o
obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
-obj-$(CONFIG_CLASSIC_RCU) += rcuclassic.o
+obj-$(CONFIG_FLAT_RCU) += rcuclassic.o
obj-$(CONFIG_TREE_RCU) += rcutree.o
obj-$(CONFIG_PREEMPT_RCU) += rcupreempt.o
obj-$(CONFIG_TREE_RCU_TRACE) += rcutree_trace.o
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8bae51a..7739ad8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -608,7 +608,7 @@ config RCU_TORTURE_TEST_RUNNABLE
config RCU_CPU_STALL_DETECTOR
bool "Check for stalled CPUs delaying RCU grace periods"
- depends on CLASSIC_RCU || TREE_RCU
+ depends on TREE_RCU || FLAT_RCU
default n
help
This option causes RCU to printk information on which
--
1.5.2.5
--
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