System freezes with SMP support enabled

[Terry Lambert]

Aleksandr Melentiev wrote:
> A quick note: I am not subscribed here yet, please reply directly to me.
> 
> Problem:
> Apparently SMP support and network do not work well together here. I have
> tried both 5.0 and 4.8 releases. Once I recompile the kernels with SMP
> support, I start getting constant 'watchdog timeout' on 5.0, network would
> halt and system would not respond. Same happens on a 4.8 machine too when I
> try to transfer files >1mb in size to an SMP machine, system would freeze,
> no error messages though. Nothing in /var/log/messages. Changing network
> cards and increasing NMBCLUSTERS doesnt help. No such problems occur
> whatsoever without SMP support.
> 
> Motherboard is an Intel N440BX with two Pentium III 500Mhz CPUs.

What are both network cards?  Are they fxp?

There are a couple of possibilities to consider...

The first is that if both cards are identical (same vendor, etc.),
you might want to use a network card from a different vendor, to
make sure it's not the network card driver.

Second, it seems to me that there's a possibility for a deadlock
if an interrupt comes in on one CPU, and an ithread to handle it
is scheduled to run on a different CPU.  You may want to try using
SCHED_4BSD to see if that changes anything.

-- Terry