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
-
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