[v3,06/18] x86/tsc: Use the full 64-bit tsc in tsc_delay

Commit Message

Andy Lutomirski June 17, 2015, 12:35 a.m. UTC

As a very minor optimization, tsc_delay was only using the low 32
bits of the TSC.  It's a delay function, so just use the whole
thing.

Signed-off-by: Andy Lutomirski <[e-mail]>
---
 arch/x86/lib/delay.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Patch

diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c
index 9a52ad0c0758..35115f3786a9 100644
--- a/arch/x86/lib/delay.c
+++ b/arch/x86/lib/delay.c
@@ -49,16 +49,16 @@  static void delay_loop(unsigned long loops)
 /* TSC based delay: */
 static void delay_tsc(unsigned long __loops)
 {
-	u32 bclock, now, loops = __loops;
+	u64 bclock, now, loops = __loops;
 	int cpu;
 
 	preempt_disable();
 	cpu = smp_processor_id();
 	rdtsc_barrier();
-	rdtscl(bclock);
+	bclock = native_read_tsc();
 	for (;;) {
 		rdtsc_barrier();
-		rdtscl(now);
+		now = native_read_tsc();
 		if ((now - bclock) >= loops)
 			break;
 
@@ -80,7 +80,7 @@  static void delay_tsc(unsigned long __loops)
 			loops -= (now - bclock);
 			cpu = smp_processor_id();
 			rdtsc_barrier();
-			rdtscl(bclock);
+			bclock = native_read_tsc();
 		}
 	}
 	preempt_enable();