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@xxxxxxx> ---- Add suggestion from Matthew Wilcox to use local variables to shorten lines. Index: linux/arch/ia64/kernel/smpboot.c =================================================================== --- linux.orig/arch/ia64/kernel/smpboot.c 2007-03-27 10:08:13.664475719 -0500 +++ linux/arch/ia64/kernel/smpboot.c 2007-03-27 14:20:44.070836177 -0500 @@ -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 - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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