[IA64] Speed up boot - skip unnecessary clock calibration
authorJack Steiner <steiner@sgi.com>
Tue, 27 Mar 2007 19:30:19 +0000 (14:30 -0500)
committerTony Luck <tony.luck@intel.com>
Thu, 29 Mar 2007 22:17:11 +0000 (15:17 -0700)
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>
arch/ia64/kernel/smpboot.c

index b21ddecea943a63f51130b20fd8372322cec29e2..ff7df439da6da98a3ecd222600866aeade40ace5 100644 (file)
@@ -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