smpboot: reuse timer calibration

NO point recalibrating for known-constant tsc ...
saves 200ms+ of boot time.

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index a78e73da4a74b351bf82407babe079b0b057fbc1..bab8a98080cf7cc5a7b3297a10d6a57e03ce3760 100644 (file)
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1569,6 +1569,9 @@ unsigned long calibrate_delay_is_known(void)
        if (!constant_tsc || !mask)
                return 0;
 
+       if (cpu != 0)
+               return cpu_data(0).loops_per_jiffy;
+
        sibling = cpumask_any_but(mask, cpu);
        if (sibling < nr_cpu_ids)
                return cpu_data(sibling).loops_per_jiffy;