IRQ, network drivers, and the like...

[Peter Van Epp]

	This doesn't seem to make any sense. The timer interrupt is a fixed
interval (probably 18 per second). If the network is heavily loaded then
the network card's interrupt rate will likely be far larger than that for the
timer in normal operation unless I'm missing something. I expect what he is
trying to say is that the timer interrupt is higher priority than the others
and if it isn't incrementing, then something is disabling interrupts for too
long and losing interrupts.

Peter Van Epp / Operations and Technical Support 
Simon Fraser University, Burnaby, B.C. Canada

> 
> Replying to my own message... love it :)
> 
>   Anyways, heres another things that lends to the idea there might be a 
> problem:
> 
> http://www.scyld.com/network/3c509.html
> - some other device or device driver hogging the bus or disabling interrupts. 
> Check /proc/interrupts for excessive interrupt counts. The timer tick 
> interrupt should always be incrementing faster than the others.
> 
> so, I check that...
>           CPU0       CPU1
>   0:     104885     102836    IO-APIC-edge  timer
>   1:          0          3    IO-APIC-edge  keyboard
>   2:          0          0          XT-PIC  cascade
>  14:          2          2    IO-APIC-edge  ide0
>  16:      58080      58093   IO-APIC-level  eth2
>  20:    3395396    3396604   IO-APIC-level  eth0
>  21:          0          0   IO-APIC-level  eth1
>  30:       8004       7985   IO-APIC-level  aic7xxx
>  31:     136694     136788   IO-APIC-level  aic7xxx
> 
> in the 33 minutes this machine has been up, it has generated 6.6 Million 
> interrupts, versus the 206,000 on the timer....
> 
> 
>   thats bad, no?
> 
> 
> Chris
> 
> 
> 
> 
> 
> 
> >===== Original Message From <carter at qosient.com> =====
> >Hey Chris,
> >   Do you mean interrupts per second?  I can understand how the
> >card could generate (3 x (the number of packet)) interrupts.
> >Start of bus transfer, end of bus transfer, and specific device
> >handler interrupt, but this is just a guess, I don't really
> >know.  Possibly Peter will have a real educated guess as to
> >what is going on, and knowing him, possibly a way around it.
> >
> >Carter
> >
> >Carter Bullard
> >QoSient, LLC
> >300 E. 56th Street, Suite 18K
> >New York, New York  10022
> >
> >carter at qosient.com
> >Phone +1 212 588-9133
> >Fax   +1 212 588-9134
> >http://qosient.com
> >
> >> -----Original Message-----
> >> From: Chris Newton [mailto:newton at unb.ca]
> >> Sent: Tuesday, September 25, 2001 1:57 PM
> >> To: carter at qosient.com
> >> Subject: IRQ, network drivers, and the like...
> >>
> >>
> >> Hi Carter,  how have you been?
> >>
> >>   I'm struggling with a weird problem and I thought maybe you
> >> might have seen
> >> this before, or be able to point me in the right direction.
> >>
> >>   One of the networks I'm watching (my big network), has (for
> >> example), about
> >> 5000 incoming packets and 5000 outgoing right now... works
> >> out to about 2MB in
> >> both directions.  That is fed into an argus box, via 1
> >> cable... so, 10K
> >> packets per second on the cable.
> >>
> >>   Whats weird.. is that right now, my network card is
> >> generating about 26 to
> >> 30,000 packets/second.  I feel this is bogging the machine...
> >> and I dont know
> >> why it might be doing that.  Argus is running, reading from
> >> that interface.
> >>
> >>   The card is a 3Com, 3c980 (or something)... but, Im not
> >> sure that matters...
> >> because I swapped it for a intel etherner express pro, and I
> >> had the same
> >> problem... (even higher actually).  There is also an ra
> >> client reading from
> >> the localargus stream.
> >>
> >>   Weird.. but, do you have any ideas?
> >>
> >>
> 
>