From ead6caae1e52a982bf09137c9b5382e9e2d52fdb Mon Sep 17 00:00:00 2001
From: Jack Steiner <steiner@sgi.com>
Date: Tue, 27 Mar 2007 14:30:19 -0500
Subject: [IA64] Speed up boot - skip unnecessary clock calibration

Skip clock calibration if cpu being brought online is exactly the same
speed, stepping, etc., as the previous cpu. This significantly reduces
the time to boot very large systems.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index b21ddec..ff7df43 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -375,6 +375,7 @@ static void __devinit
 smp_callin (void)
 {
 	int cpuid, phys_id, itc_master;
+	struct cpuinfo_ia64 *last_cpuinfo, *this_cpuinfo;
 	extern void ia64_init_itm(void);
 	extern volatile int time_keeper_id;
 
@@ -424,7 +425,21 @@ smp_callin (void)
 	 * Get our bogomips.
 	 */
 	ia64_init_itm();
-	calibrate_delay();
+
+	/*
+	 * Delay calibration can be skipped if new processor is identical to the
+	 * previous processor.
+	 */
+	last_cpuinfo = cpu_data(cpuid - 1);
+	this_cpuinfo = local_cpu_data;
+	if (last_cpuinfo->itc_freq != this_cpuinfo->itc_freq ||
+	    last_cpuinfo->proc_freq != this_cpuinfo->proc_freq ||
+	    last_cpuinfo->features != this_cpuinfo->features ||
+	    last_cpuinfo->revision != this_cpuinfo->revision ||
+	    last_cpuinfo->family != this_cpuinfo->family ||
+	    last_cpuinfo->archrev != this_cpuinfo->archrev ||
+	    last_cpuinfo->model != this_cpuinfo->model)
+		calibrate_delay();
 	local_cpu_data->loops_per_jiffy = loops_per_jiffy;
 
 #ifdef CONFIG_IA32_SUPPORT
-- 
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