From: Jack Steiner <steiner@sgi.com>
Date: Tue, 27 Mar 2007 19:30:19 +0000 (-0500)
Subject: [IA64] Speed up boot - skip unnecessary clock calibration
X-Git-Tag: v2.6.21-rc6~46^2~1
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ead6caae1e52a982bf09137c9b5382e9e2d52fdb;p=linux-2.6

[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 b21ddecea9..ff7df439da 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