Re: i386: Selectable Frequency of the Timer Interrupt

Jan Engelhardt
2005-07-12T14:09:21Z

Hi,

>> > HZ ticks/jiffie 1 second error (ppm)
>> > ---------------------------------------------------
>> > 100 11932 1.000015238 15.2

I was not quite able to reproduce these values, probably because I got the
math wrong. I used:
$oneSecond = $ticksJiffie * $HZ / 1193182
which yields 11932*100/1193182 = 1.00001508571198693912, !=1.000015238
Math corrections welcome.

Anyway, I've done some graphs. Intersting that the smaller the HZ, the less
error (seen on a whole, esp. view_1k and view_8k.png) we get. 20Hz seems to
be the 0.0 case, and 18Hz is not bad either. IIRC, DOS used 18HZ ;)
http://jengelh.hopto.org/tick/

Jan Engelhardt
--
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