1 files changed, 23 insertions, 3 deletions

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index db483369f10b..c0dd5b603749 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -35,7 +35,7 @@ static int __read_mostly tsc_unstable;
    erroneous rdtsc usage on !cpu_has_tsc processors */
 static int __read_mostly tsc_disabled = -1;
 
-static int tsc_clocksource_reliable;
+int tsc_clocksource_reliable;
 /*
  * Scheduler clock - returns current time in nanosec units.
  */
@@ -178,11 +178,11 @@ static unsigned long calc_pmtimer_ref(u64 deltatsc, u64 pm1, u64 pm2)
 }
 
 #define CAL_MS          10
-#define CAL_LATCH       (CLOCK_TICK_RATE / (1000 / CAL_MS))
+#define CAL_LATCH       (PIT_TICK_RATE / (1000 / CAL_MS))
 #define CAL_PIT_LOOPS   1000
 
 #define CAL2_MS         50
-#define CAL2_LATCH      (CLOCK_TICK_RATE / (1000 / CAL2_MS))
+#define CAL2_LATCH      (PIT_TICK_RATE / (1000 / CAL2_MS))
 #define CAL2_PIT_LOOPS  5000
 
 
@@ -995,3 +995,23 @@ void __init tsc_init(void)
         check_system_tsc_reliable();
 }
 
+#ifdef CONFIG_SMP
+/*
+ * If we have a constant TSC and are using the TSC for the delay loop,
+ * we can skip clock calibration if another cpu in the same socket has already
+ * been calibrated. This assumes that CONSTANT_TSC applies to all
+ * cpus in the socket - this should be a safe assumption.
+ */
+unsigned long __cpuinit calibrate_delay_is_known(void)
+{
+        int i, cpu = smp_processor_id();
+
+        if (!tsc_disabled && !cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC))
+                return 0;
+
+        for_each_online_cpu(i)
+                if (cpu_data(i).phys_proc_id == cpu_data(cpu).phys_proc_id)
+                        return cpu_data(i).loops_per_jiffy;
+        return 0;
+}
+#endif