Messages in this thread | | | Subject | Re: PCI parallel card causes erratic timekeeping? (2.4.21) | From | john stultz <> | Date | 12 Aug 2003 14:13:34 -0700 |
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On Sun, 2003-08-10 at 00:26, Ryan Underwood wrote: > In the ISA slot, up until recently, we had a dual parallel port card > that was attached to the network printers. However, the printers and > the card were fried in a storm recently; luckily, the server survived. > We replaced the card with a dual PCI parallel port card (Netmos > NM9715CV) and the printers are now working fine. > > However, a new problem emerged. The software clock of the system is > crazy! Sometimes it is very fast, other times very slow. NTP > constantly loses synchronization, and since this machine is also a > Kerberos KDC, Kerberos tickets are flakey. :( This problem exists > independently of whether a driver is loaded for the card or not; if it > is in the system at all, the clock runs screwy. If I remove the card, > the clock is back to normal as far as I can tell.
[snip]
> Can simply inserting a card generally make a system clock act screwy > like this? Should I try to find a different card?
Sounds like the card is blocking the timer interrupt from being handled. This would cause a loss in time as well as time inconsistencies. I'm a bit curious about time running too fast, though. It could be NTP trying to compensate for the slowness and then overcompensates if the card stops misbehaving. Its also possible calibrate_tsc is being confused by the card's funkyness. It would be interesting to see what Bogomips is being reported as the system acts up.
Sounds like a bad card to me.
thanks -john
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