commit 9c679215248e837b34242632d5a22adf9a247021
Author: Rene Herman <rene.herman@gmail.com>
Date:   Wed Feb 20 12:52:30 2008 +0100

    x86: per CPU family loops_per_jiffy initialization
    
    Following the current port 0x80 I/O delay replacements we need
    microseconds to be somewhat usefully defined pre calibration.
    
    Initialize 386, 486 and Pentium 1 as fastest in their families
    and higher CPUs (including 64-bit) at 1 Ghz. Note that trouble
    should be absent past family 5 systems anyway.
    
    Signed-off-by: Rene Herman <rene.herman@gmail.com>

diff --git a/arch/x86/kernel/time_32.c b/arch/x86/kernel/time_32.c
index 1a89e93..e33e70b 100644
--- a/arch/x86/kernel/time_32.c
+++ b/arch/x86/kernel/time_32.c
@@ -32,6 +32,7 @@
 #include <linux/interrupt.h>
 #include <linux/time.h>
 #include <linux/mca.h>
+#include <linux/delay.h>
 
 #include <asm/arch_hooks.h>
 #include <asm/hpet.h>
@@ -134,6 +135,17 @@ void __init hpet_time_init(void)
  */
 void __init time_init(void)
 {
+	switch (boot_cpu_data.x86) {
+	case 3:
+		loops_per_jiffy = LOOPS_PER_JIFFY_386;
+		break;
+	case 4:
+		loops_per_jiffy = LOOPS_PER_JIFFY_486;
+		break;
+	case 5:
+		loops_per_jiffy = LOOPS_PER_JIFFY_586;
+		break;
+	}
 	tsc_init();
 	late_time_init = choose_time_init();
 }
diff --git a/include/asm-x86/delay.h b/include/asm-x86/delay.h
index 409a649..d0fbaf6 100644
--- a/include/asm-x86/delay.h
+++ b/include/asm-x86/delay.h
@@ -7,6 +7,11 @@
  * Delay routines calling functions in arch/x86/lib/delay.c
  */
 
+#define LOOPS_PER_JIFFY_386	(4000000 / HZ)	  /* 386 at 40 Mhz */
+#define LOOPS_PER_JIFFY_486	(30000000 / HZ)	  /* 486 at 120 MHz */
+#define LOOPS_PER_JIFFY_586	(233000000 / HZ)  /* Pentium 1 at 233 Mhz */
+#define LOOPS_PER_JIFFY		(1000000000 / HZ) /* P6+ at 1 GHz */
+
 /* Undefined functions to get compile-time errors */
 extern void __bad_udelay(void);
 extern void __bad_ndelay(void);
diff --git a/init/main.c b/init/main.c
index 8b19820..94862c8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -228,12 +228,11 @@ static int __init obsolete_checksetup(char *line)
 	return had_early_param;
 }
 
-/*
- * This should be approx 2 Bo*oMips to start (note initial shift), and will
- * still work even if initially too large, it will just take slightly longer
- */
-unsigned long loops_per_jiffy = (1<<12);
+#ifndef LOOPS_PER_JIFFY
+#define LOOPS_PER_JIFFY	(1 << 12)
+#endif
 
+unsigned long loops_per_jiffy = LOOPS_PER_JIFFY;
 EXPORT_SYMBOL(loops_per_jiffy);
 
 static int __init debug_kernel(char *str)