Re: [PATCH] HZ==100 assumptions

Riley Williams (rhw@MemAlpha.CX)
Wed, 28 Jul 1999 22:34:49 +0100 (GMT)


Hi Eric.

>> However, the standard used by MSDOS (which I assume is what
>> you're referring to) is for the clock to tick ~18.2 times per
>> second (to be more accurate, 65536 ticks per hour), in which
>> case the correct

> This is incorrect. The BIOS/MSDOS clock is generated from a
> 14.31818MHz crystal clock divided by 12 * 65536.

Curious...

Q> # echo 8k14318180 12 / 65536 /p | dc
Q> 18.20650736
Q> #

...since that also gives ~18.2 ticks per second, thus confirming my
claim that the MSDOS standard is ~18.2 ticks per second, rather than
one tick every 18.2 ms as claimed by the original poster.

For reference...

Q> # echo 2k 1000 18.2 /p | dc
Q> 54.94
Q> #

...18.2 ticks per second corresponds to a tick every ~55 ms, not every
18.2 ms as was claimed.

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html

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