linux-kernel - [PATCH 3/7] Simple Performance Counters: i386 support

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Message-Id: <11859243121503-git-send-email-clameter@sgi.com>
Date:	Tue, 31 Jul 2007 16:25:08 -0700
From:	Christoph Lameter <clameter@....com>
To:	linux-kernel@...r.kernel.org
Cc:	Christoph Lameter <clameter@....com>
Subject: [PATCH 3/7] Simple Performance Counters: i386 support

Export a cycles_to_ns function

Signed-off-by: Christoph Lameter <clameter@....com>
---
 arch/i386/kernel/tsc.c   |    2 +-
 include/asm-i386/timex.h |    8 ++++++++
 2 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index debd7db..c150ac0 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -118,7 +118,7 @@ unsigned long long native_sched_clock(void)
 	rdtscll(this_offset);
 
 	/* return the value in ns */
-	return cycles_2_ns(this_offset);
+	return cycles_to_ns(this_offset);
 }
 
 /* We need to define a real function for sched_clock, to override the
diff --git a/include/asm-i386/timex.h b/include/asm-i386/timex.h
index 3666044..37b0338 100644
--- a/include/asm-i386/timex.h
+++ b/include/asm-i386/timex.h
@@ -19,4 +19,12 @@
 extern int read_current_timer(unsigned long *timer_value);
 #define ARCH_HAS_READ_CURRENT_TIMER	1
 
+extern long cyc2ns_scale;
+#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
+
+static inline unsigned long long cycles_to_ns(unsigned long long cyc)
+{
+	return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
+}
+
 #endif
-- 
1.5.2.4

-
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