View topic - SLOW CLOCK

SLOW CLOCK

General Help about QNX

SLOW CLOCK

Postby jk » Tue Sep 22, 2009 7:44 pm

Hi all

I am experiencing a problem of slow system clock
(ie)
If i run the QNX Date utility in my system it shows

# date
Tue Sep 22 13:12:30 UTC 2009
"After 1.5 hrs in the external calibrated stop watch"
# date
Tue Sep 22 14:17:52 UTC 2009

It is about 24 mins slower than the stop watch
Do anyone have experienced this problem
Is there anyone who can help me on this

Thanks in advance for the support
Regds
JK
jk
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RE: SLOW CLOCK

Postby mario » Tue Sep 22, 2009 9:02 pm

Unless there is a hardware problem with your machine, it typicaly mean interrupts are disabled for long period of time or some process is running at higher priority then Proc (very unlikely with default setup)
mario
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RE: SLOW CLOCK

Postby jk » Wed Sep 23, 2009 1:55 pm

Thanks Mario, is there any way that we can confirm that hardware timer interrupts are delayed?
Is there any utility to confirm?

Thanks In Advance
JK
jk
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Posts: 24
Joined: Mon Sep 29, 2008 1:47 pm

RE: SLOW CLOCK

Postby maschoen » Wed Sep 23, 2009 3:30 pm

If the slowness is significant, say 1% or more off, you could write a program that hooks the tic interrupt and counts them. Then report every computer minute and sync it against an accurate clock. You should be able to see a problem within a few minutes.
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RE: SLOW CLOCK

Postby mario » Wed Sep 23, 2009 4:40 pm

I forgot to mention, that SMI can be responsable too. We've seen some computer being slow down by a crappy USB mouse that was sending garbage. It was handle through SMI because BIOS was set in emulation mode.
mario
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RE: SLOW CLOCK

Postby jk » Mon Sep 28, 2009 6:18 pm

Thanks Mario and maschoen, you guys are correct the problem was due to the HW, there were false interrupts that was triggered by the unused com ports hence delaying the timer interrupt

Thanks again for your time and help

Regds
JK
jk
Active Member
 
Posts: 24
Joined: Mon Sep 29, 2008 1:47 pm


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