RE: clock drift with two Promise Ultra133 TX2 (PDC 20269) cards

[Drew Winstel]

> Are interrupts errors serious? Can anyone tell? The error count was higher
> when I had a fifth PCI card in the computer (natsemi ethernet NIC).
> Could there be some kind of PCI card conflict? Maybe I should try to
> remove a few of them...

It's worth a shot. Just for the record, I haven't had any such errors on my
machine.
root@linux /proc # cat interrupts 
           CPU0       
  0:   46494411          XT-PIC  timer
  1:      13644          XT-PIC  i8042
  2:          0          XT-PIC  cascade
  5:    1210194          XT-PIC  ohci_hcd, SiS SI7012
  7:         19          XT-PIC  parport0
  9:    3492898          XT-PIC  acpi, ohci_hcd, nvidia
 10:          0          XT-PIC  ohci_hcd
 11:      29194          XT-PIC  ehci_hcd, eth0
 12:     295381          XT-PIC  i8042
 14:     567754          XT-PIC  ide0
 15:         48          XT-PIC  ide1
NMI:          0 
ERR:          0
root@linux /proc # uptime
 09:38:16 up 12:54,  5 users,  load average: 0.08, 0.03, 0.03

> In other words, Athlon/Duron/K7 + HPET + Local APIC + IO-Apic
> (though I have tried with both XT-PIC and Local APIC, with same
> drift).

So much for that thought.  The kernel config is solid (as expected).

> And no, the clock drift occurs no matter if ntpd is running or not.
> It's having a very hard time to syncronize with the remote servers,
> because the clock drift is too high. (It also says somewhere in the
> NTP documentation that it doesn't handle too high clock drift.)

I just had an idea.  Using the old PDC20269 IDE driver, try repeating
your test to trigger clock drift.  While the test is in progress, run
hdparm (no need for -i) on both drives.  I wonder if it's dropping out
of DMA mode temporarily for no apparent reason.

Thanks,
Drew
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