Re: No 100 HZ timer!

Chris Wedgwood
2001-04-16T21:30:09Z

On Mon, Apr 16, 2001 at 04:45:39PM -0400, Albert D. Cahalan wrote:

> CLOCK_10MS a wall clock supporting timers with 10 ms resolution (same as
> linux today).

Except on the Alpha, and on some ARM systems, etc.
The HZ constant varies from 10 to 1200.

Or some people use higher values on x86:

cw@charon(cw)$ uptime
14:13:02 up 11 days, 21:44, 2 users, load average: 0.00, 0.00, 0.00
cw@charon(cw)$ cat /proc/interrupts
CPU0
0: 2106736381 XT-PIC timer
1: 187633 XT-PIC keyboard
2: 0 XT-PIC cascade
7: 94128650 XT-PIC eth0, usb-uhci, usb-uhci
10: 18265929 XT-PIC ide2
12: 3107415 XT-PIC PS/2 Mouse
14: 753375 XT-PIC via82cxxx
15: 2 XT-PIC ide1
NMI: 0
ERR: 0

thats 2048 ticks/sec -- I had to hack the kernel in a couple of
places to make things happy with that, but so far it seems to work.

I also had to hack libproc.so.* -- what a terribly obscure way that
it uses to determine what HZ is defined as!

I know this has ben beaten to death before but can someone tell me:

- why we cannot export HZ somewhere

- why is it called HZ, it seems misleading why not something like
TICKS_PER_SECOND or similar

- it seems there are a couple of places that assume HZ==100 still,
or am I just imagining this (ide code, I forget where now)

--cw