[tulip] problem with tulip card ceasing to function - requires ifup/ifdown to fix

Donald Becker becker@scyld.com
Mon Nov 26 16:18:00 2001

On Mon, 26 Nov 2001 dani-post@roisman.com wrote:
> On Mon, Nov 26, 2001 at 01:59:13PM -0500, Donald Becker wrote:
> > On Mon, 26 Nov 2001 dani-post@roisman.com wrote:
> > Was this when the chip stopped?  Or after you restarted?
> after the restart.  sorry I didn't grab stats during the problem, the
> heat was on to get the firewall up again. 

The diagnostic information reports the state of the chip.  The driver
completely reinitializes the chip when the interface is restarted.

> > Hmmm, you either have an extreme burst of small packets, or some other
> > driver is hogging the machine.  The status is reporting a normal receive
> > done interrupt.
> Is it expected behavior that a burst of small packets cause the card
> to cease passing traffic? 

No.  And your error log indicated that the driver did the Right Thing
when confronted with too much work: it repeatedly yeilded the machine to
other interrupt handlers.  With a 21143-TD chip, it also enabled the
hardware support for interrupt mitigation.

> > Try changing the max_interrupt_work paramter from the default of 25 to 100
> > in /etc/modules.conf
> > 
> > options tulip max_interrupt_work=100
> Can you help me understand exactly what that number means? 

It's the limit for actions taken during a single call of the interrupt
handler.  Device driver should have a work limit on every loop,
especially interrupt handlers.  But few non-network drivers are written
with checks.  That means the network device driver is often the only
thing that complains when something unusual is happening on the system.

> Also, I have the driver compiled in, not loaded as a module.  How
> could I change in in my situation? 

Either a kernel debugger, or changing the source code and recompiling
your kernel.

Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993