From: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
Date: Fri, 9 Sep 2011 05:37:11 +0000 (-0700)
Subject: Optimize caa_get_cycles() for PowerPC64
X-Git-Tag: v0.6.5~30
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=9a9d403acee72d36d17988ae5a6ce9ede8051f11;p=userspace-rcu.git

Optimize caa_get_cycles() for PowerPC64

Make caa_get_cycles() read from the Time Base register with only 1
instruction.

[ Edit by Mathieu Desnoyers: coding style update ]

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
---

diff --git a/urcu/arch/ppc.h b/urcu/arch/ppc.h
index d7317bb..a03d688 100644
--- a/urcu/arch/ppc.h
+++ b/urcu/arch/ppc.h
@@ -48,11 +48,24 @@ extern "C" {
 		rval;					\
 	})
 
+#define mftb()						\
+	({						\
+		unsigned long long rval;		\
+		asm volatile("mftb %0" : "=r" (rval));	\
+		rval;					\
+	})
+
 typedef unsigned long long cycles_t;
 
-static inline cycles_t caa_get_cycles (void)
+#ifdef __powerpc64__
+static inline cycles_t caa_get_cycles(void)
 {
-	long h, l;
+	return (cycles_t) mftb();
+}
+#else
+static inline cycles_t caa_get_cycles(void)
+{
+	unsigned long h, l;
 
 	for (;;) {
 		h = mftbu();
@@ -63,6 +76,7 @@ static inline cycles_t caa_get_cycles (void)
 			return (((cycles_t) h) << 32) + l;
 	}
 }
+#endif
 
 #ifdef __cplusplus 
 }