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

Andy Lutomirski
2015-06-17T00:37:15Z

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 <luto@kernel.org>
---
arch/x86/lib/delay.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

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();
--
2.4.2