From: Jack Steiner <steiner@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: [PATCH] - Speed up boot - skip unnecessary clock calibration
Date: Tue, 27 Mar 2007 13:29:54 +0000 [thread overview]
Message-ID: <20070327132953.GA14401@sgi.com> (raw)
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>
Index: linux/arch/ia64/kernel/smpboot.c
=================================--- linux.orig/arch/ia64/kernel/smpboot.c 2007-03-26 15:04:29.322256475 -0500
+++ linux/arch/ia64/kernel/smpboot.c 2007-03-27 08:26:41.914042190 -0500
@@ -424,7 +424,19 @@ 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.
+ */
+ if (local_cpu_data->itc_freq != per_cpu(cpu_info, cpuid - 1).itc_freq ||
+ local_cpu_data->proc_freq != per_cpu(cpu_info, cpuid - 1).proc_freq ||
+ local_cpu_data->features != per_cpu(cpu_info, cpuid - 1).features ||
+ local_cpu_data->revision != per_cpu(cpu_info, cpuid - 1).revision ||
+ local_cpu_data->family != per_cpu(cpu_info, cpuid - 1).family ||
+ local_cpu_data->archrev != per_cpu(cpu_info, cpuid - 1).archrev ||
+ local_cpu_data->model != per_cpu(cpu_info, cpuid - 1).model)
+ calibrate_delay();
local_cpu_data->loops_per_jiffy = loops_per_jiffy;
#ifdef CONFIG_IA32_SUPPORT
next reply other threads:[~2007-03-27 13:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-27 13:29 Jack Steiner [this message]
2007-03-27 17:53 ` [PATCH] - Speed up boot - skip unnecessary clock calibration Matthew Wilcox
2007-03-27 18:42 ` Luck, Tony
2007-03-27 19:17 ` Yu, Fenghua
2007-03-27 19:22 ` Jack Steiner
2007-03-27 19:30 ` Jack Steiner
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