Re: Changing clock speed

Yaron J.G. Bandell (bandell-nfo@I-MaSs.nl)
Tue, 23 Feb 1999 01:25:41 +0100


Bruce Guenter wrote:
>
> Greetings.
>
> As I was trying to track down a problem with the clock on a router
> behaving erratically, I ran a simple loop benchmark repeatedly and
> observed that the time taken to run the loop varied by a factor of four.
> I've attached a copy of the trivial code I've been using as a test. The
> output that I'm seeing is similar to the following:
<program output removed>
> There are no other processes running on this that would consume
> significant amounts of CPU time. It is a AMD K6 at 233MHz routing
> between three relatively 10Base Ethernet networks, running the 2.0.36
> kernel (as compiled by RedHat :-).
>
> Is there a problem with my methodology, or is there something really odd
> going on with this computer?
> --
> Bruce Guenter, QCC Communications Corp. EMail: bruce.guenter@qcc.sk.ca
> Phone: (306)249-0220 WWW: http://www.qcc.sk.ca/~bguenter/
>
<program code removed>
>

I have a production machine which also is an AMD K6-233, running
2.0.37-pre4.
This machine has a light load but also managed to have a clock skew of
over 20 minutes each day (okay, light, I got an totally niced rc5 client
running too). I solved it by running '/sbin/clock -r' to read the time
from the CMOS which does keep a correct time. Maybe it has something to
do with the fact that it's and AMD-K6 233Mhz or the rc5 client with MMX
extensions might do something weird, I dunno.

-Yaron Bandell.

Machine Info:

gcc: 2.7.2.3

cpuinfo:

processor : 0
cpu : 586
model : AMD-K6tm w/ multimedia extensions
vendor_id : AuthenticAMD
stepping : B
fdiv_bug : no
hlt_bug : no
f00f_bug : no
fpu : yes
fpu_exception : yes
cpuid : yes
wp : yes
flags : fpu vme de pse tsc msr mce cx8 10 mmx
bogomips : 400.59

/proc/interrupts: (after 20 days of uptime)

0: 177172668 timer
1: 8 keyboard
2: 0 cascade
5: 33282544 eth0
10: 1132634 aha1542
13: 1 math error
14: 4239709 + ide0

===============================================================================
Network Consultancy Bandell - Noordmolenwerf 113 - 3011 DC
ROTTERDAM, NL
Tel: +31-10-4045822 / +31-6-54746092 - bandell@I-MaSs.nl
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