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Subject[PATCH 1/3] mull'ify multiplication with HZ in __const_udelay() [Was: Re: Too much error in __const_udelay() ?]
Move the multiplication of (loops_per_jiffy * xloops) with HZ into
the "mull" asm operation. This increases the accuracy of the delay functions
largely:

n usec delay on a 1500000 BogoMIPS system:

n before after
1 1000 ticks 1499 ticks
10 14000 ticks 14999 ticks

n usec delay on a 100000 BogoMIPS system:

n before after
1 0 ticks 99 ticks
10 0 ticks 999 ticks
100 9000 ticks 9999 ticks


Signed-off-by: Dominik Brodowski <linux@brodo.de>


diff -ruN linux-original/arch/i386/lib/delay.c linux/arch/i386/lib/delay.c
--- linux-original/arch/i386/lib/delay.c 2004-06-07 22:01:46.608351088 +0200
+++ linux/arch/i386/lib/delay.c 2004-06-07 22:05:03.299449496 +0200
@@ -33,8 +33,8 @@
int d0;
__asm__("mull %0"
:"=d" (xloops), "=&a" (d0)
- :"1" (xloops),"0" (current_cpu_data.loops_per_jiffy));
- __delay(xloops * HZ);
+ :"1" (xloops),"0" (current_cpu_data.loops_per_jiffy * HZ));
+ __delay(xloops);
}

void __udelay(unsigned long usecs)
-
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