[this_cpu_xx V9 4/7] Generic inc / dec percpu instructions

[Christoph Lameter]

Optimize code generated for percpu access by checking for increment and
decrements.

Signed-off-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>

---
 arch/x86/include/asm/percpu.h |  100 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 86 insertions(+), 14 deletions(-)

Index: linux-2.6/arch/x86/include/asm/percpu.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/percpu.h	2010-01-04 15:33:02.000000000 -0600
+++ linux-2.6/arch/x86/include/asm/percpu.h	2010-01-04 16:11:29.000000000 -0600
@@ -104,6 +104,78 @@ do {							\
 	}						\
 } while (0)
 
+/*
+ * Generate a percpu add to memory instruction and optimize code
+ * if a one is added or subtracted.
+ */
+#define percpu_add_op(var, val)				\
+do {							\
+	typedef typeof(var) pto_T__;			\
+	if (0) {					\
+		pto_T__ pto_tmp__;			\
+		pto_tmp__ = (val);			\
+	}						\
+	switch (sizeof(var)) {				\
+	case 1:						\
+		if (__builtin_constant_p(val) == 1)	\
+		  asm("incb "__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : );				\
+		else if (__builtin_constant_p(val) == -1) \
+		  asm("decb "__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : );				\
+		else					\
+		  asm("addb %1,"__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : "qi" ((pto_T__)(val)));		\
+		break;					\
+	case 2:						\
+		if (__builtin_constant_p(val) == 1)	\
+		  asm("incw "__percpu_arg(0)	\
+		    : "+m" (var)			\
+		    : );				\
+		else if (__builtin_constant_p(val) == -1) \
+		  asm("decw "__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : );				\
+		else					\
+		asm("addw %1,"__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : "ri" ((pto_T__)(val)));		\
+		break;					\
+	case 4:						\
+		if (__builtin_constant_p(val) == 1)	\
+		  asm("incl "__percpu_arg(0)	\
+		    : "+m" (var)			\
+		    : );				\
+		else if (__builtin_constant_p(val) == -1) \
+		  asm("decl "__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : );				\
+		else					\
+		asm("addl %1,"__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : "ri" ((pto_T__)(val)));		\
+		break;					\
+	case 8:						\
+		if (__builtin_constant_p(val) == 1)	\
+		  asm("incq "__percpu_arg(0)	\
+		    : "+m" (var)			\
+		    : );				\
+		else if (__builtin_constant_p(val) == -1) \
+		  asm("decq "__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : );				\
+		else					\
+		asm("addq %1,"__percpu_arg(0)		\
+		    : "+m" (var)			\
+		    : "re" ((pto_T__)(val)));		\
+		break;					\
+	default: __bad_percpu_size();			\
+	}						\
+} while (0)
+
 #define percpu_from_op(op, var, constraint)		\
 ({							\
 	typeof(var) pfo_ret__;				\
@@ -147,8 +219,8 @@ do {							\
 #define percpu_read_stable(var)	percpu_from_op("mov", per_cpu__##var,	\
 					       "p" (&per_cpu__##var))
 #define percpu_write(var, val)	percpu_to_op("mov", per_cpu__##var, val)
-#define percpu_add(var, val)	percpu_to_op("add", per_cpu__##var, val)
-#define percpu_sub(var, val)	percpu_to_op("sub", per_cpu__##var, val)
+#define percpu_add(var, val)	percpu_add_op(per_cpu__##var, val)
+#define percpu_sub(var, val)	percpu_add_op(per_cpu__##var, -(val))
 #define percpu_and(var, val)	percpu_to_op("and", per_cpu__##var, val)
 #define percpu_or(var, val)	percpu_to_op("or", per_cpu__##var, val)
 #define percpu_xor(var, val)	percpu_to_op("xor", per_cpu__##var, val)
@@ -160,9 +232,9 @@ do {							\
 #define __this_cpu_write_1(pcp, val)	percpu_to_op("mov", (pcp), val)
 #define __this_cpu_write_2(pcp, val)	percpu_to_op("mov", (pcp), val)
 #define __this_cpu_write_4(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define __this_cpu_add_1(pcp, val)	percpu_to_op("add", (pcp), val)
-#define __this_cpu_add_2(pcp, val)	percpu_to_op("add", (pcp), val)
-#define __this_cpu_add_4(pcp, val)	percpu_to_op("add", (pcp), val)
+#define __this_cpu_add_1(pcp, val)	percpu_add_op((pcp), val)
+#define __this_cpu_add_2(pcp, val)	percpu_add_op((pcp), val)
+#define __this_cpu_add_4(pcp, val)	percpu_add_op((pcp), val)
 #define __this_cpu_and_1(pcp, val)	percpu_to_op("and", (pcp), val)
 #define __this_cpu_and_2(pcp, val)	percpu_to_op("and", (pcp), val)
 #define __this_cpu_and_4(pcp, val)	percpu_to_op("and", (pcp), val)
@@ -179,9 +251,9 @@ do {							\
 #define this_cpu_write_1(pcp, val)	percpu_to_op("mov", (pcp), val)
 #define this_cpu_write_2(pcp, val)	percpu_to_op("mov", (pcp), val)
 #define this_cpu_write_4(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define this_cpu_add_1(pcp, val)	percpu_to_op("add", (pcp), val)
-#define this_cpu_add_2(pcp, val)	percpu_to_op("add", (pcp), val)
-#define this_cpu_add_4(pcp, val)	percpu_to_op("add", (pcp), val)
+#define this_cpu_add_1(pcp, val)	percpu_add_op((pcp), val)
+#define this_cpu_add_2(pcp, val)	percpu_add_op((pcp), val)
+#define this_cpu_add_4(pcp, val)	percpu_add_op((pcp), val)
 #define this_cpu_and_1(pcp, val)	percpu_to_op("and", (pcp), val)
 #define this_cpu_and_2(pcp, val)	percpu_to_op("and", (pcp), val)
 #define this_cpu_and_4(pcp, val)	percpu_to_op("and", (pcp), val)
@@ -192,9 +264,9 @@ do {							\
 #define this_cpu_xor_2(pcp, val)	percpu_to_op("xor", (pcp), val)
 #define this_cpu_xor_4(pcp, val)	percpu_to_op("xor", (pcp), val)
 
-#define irqsafe_cpu_add_1(pcp, val)	percpu_to_op("add", (pcp), val)
-#define irqsafe_cpu_add_2(pcp, val)	percpu_to_op("add", (pcp), val)
-#define irqsafe_cpu_add_4(pcp, val)	percpu_to_op("add", (pcp), val)
+#define irqsafe_cpu_add_1(pcp, val)	percpu_add_op((pcp), val)
+#define irqsafe_cpu_add_2(pcp, val)	percpu_add_op((pcp), val)
+#define irqsafe_cpu_add_4(pcp, val)	percpu_add_op((pcp), val)
 #define irqsafe_cpu_and_1(pcp, val)	percpu_to_op("and", (pcp), val)
 #define irqsafe_cpu_and_2(pcp, val)	percpu_to_op("and", (pcp), val)
 #define irqsafe_cpu_and_4(pcp, val)	percpu_to_op("and", (pcp), val)
@@ -212,19 +284,19 @@ do {							\
 #ifdef CONFIG_X86_64
 #define __this_cpu_read_8(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
 #define __this_cpu_write_8(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define __this_cpu_add_8(pcp, val)	percpu_to_op("add", (pcp), val)
+#define __this_cpu_add_8(pcp, val)	percpu_add_op((pcp), val)
 #define __this_cpu_and_8(pcp, val)	percpu_to_op("and", (pcp), val)
 #define __this_cpu_or_8(pcp, val)	percpu_to_op("or", (pcp), val)
 #define __this_cpu_xor_8(pcp, val)	percpu_to_op("xor", (pcp), val)
 
 #define this_cpu_read_8(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
 #define this_cpu_write_8(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define this_cpu_add_8(pcp, val)	percpu_to_op("add", (pcp), val)
+#define this_cpu_add_8(pcp, val)	percpu_add_op((pcp), val)
 #define this_cpu_and_8(pcp, val)	percpu_to_op("and", (pcp), val)
 #define this_cpu_or_8(pcp, val)		percpu_to_op("or", (pcp), val)
 #define this_cpu_xor_8(pcp, val)	percpu_to_op("xor", (pcp), val)
 
-#define irqsafe_cpu_add_8(pcp, val)	percpu_to_op("add", (pcp), val)
+#define irqsafe_cpu_add_8(pcp, val)	percpu_add_op((pcp), val)
 #define irqsafe_cpu_and_8(pcp, val)	percpu_to_op("and", (pcp), val)
 #define irqsafe_cpu_or_8(pcp, val)	percpu_to_op("or", (pcp), val)
 #define irqsafe_cpu_xor_8(pcp, val)	percpu_to_op("xor", (pcp), val)

-- 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/