linux-kernel - [PATCH 1/2] x86: Define early read-mostly per-cpu macros

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Message-Id: <201204241429.35827.vlad@scalemp.com>
Date:	Tue, 24 Apr 2012 14:29:35 +0300
From:	Vlad Zolotarov <vlad@...lemp.com>
To:	"linux-kernel" <linux-kernel@...r.kernel.org>
Cc:	alan@...rguk.ukuu.org.uk,
	"Shai Fultheim (Shai@...leMP.com)" <Shai@...lemp.com>,
	ido@...ery.com, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>
Subject: [PATCH 1/2] x86: Define early read-mostly per-cpu macros

From: Ido Yariv <ido@...ery.com>

Some read-mostly per-cpu data may need to be declared or defined early,
so it can be initialized and accessed before per_cpu areas are
allocated.

Only the data that resides in the per_cpu areas should be read-mostly,
as there is little benefit in optimizing cache lines on initialization.

Signed-off-by: Ido Yariv <ido@...ery.com>
Signed-off-by: Shai Fultheim <shai@...lemp.com>
Signed-off-by: Vlad Zolotarov <vlad@...lemp.com>
---
 arch/x86/include/asm/percpu.h |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 7a11910..6568662 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -555,6 +555,12 @@ DECLARE_PER_CPU(unsigned long, this_cpu_off);
 				{ [0 ... NR_CPUS-1] = _initvalue };	\
 	__typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
 
+#define DEFINE_EARLY_PER_CPU_READ_MOSTLY(_type, _name, _initvalue)	\
+	DEFINE_PER_CPU_READ_MOSTLY(_type, _name) = _initvalue;		\
+	__typeof__(_type) _name##_early_map[NR_CPUS] __initdata =	\
+				{ [0 ... NR_CPUS-1] = _initvalue };	\
+	__typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
+
 #define EXPORT_EARLY_PER_CPU_SYMBOL(_name)			\
 	EXPORT_PER_CPU_SYMBOL(_name)
 
@@ -563,6 +569,11 @@ DECLARE_PER_CPU(unsigned long, this_cpu_off);
 	extern __typeof__(_type) *_name##_early_ptr;		\
 	extern __typeof__(_type)  _name##_early_map[]
 
+#define DECLARE_EARLY_PER_CPU_READ_MOSTLY(_type, _name)		\
+	DECLARE_PER_CPU_READ_MOSTLY(_type, _name);		\
+	extern __typeof__(_type) *_name##_early_ptr;		\
+	extern __typeof__(_type)  _name##_early_map[]
+
 #define	early_per_cpu_ptr(_name) (_name##_early_ptr)
 #define	early_per_cpu_map(_name, _idx) (_name##_early_map[_idx])
 #define	early_per_cpu(_name, _cpu) 				\
-- 
1.7.7.6

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