From: Arjan van de Ven <arjan@linux.intel.com>
Date: Wed, 11 Feb 2015 23:28:14 +0000 (-0600)
Subject: smpboot: reuse timer calibration
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=57d1862db788a4c92b190f3b1364f4d5744ba623;p=users%2Fdwmw2%2Flinux.git

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 2e076a459a0c0..94bc1166476ed 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1549,6 +1549,9 @@ 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;