On Sun, 2004-01-11 at 14:29, Jeff Garzik wrote:
> Douglas Pollock wrote:
> The kernel comes with "pktgen" which is a free packet generator you can 
> use for stressing kernels and LANs.  There is also ttcp, nttcp, various 
> filesystems tests over NFS (such as bonnie++), various block device 
> tests over nbd (network block device), ...

Thanks for that.  I should have remembered the packet generator.  Using
pktgen, I am able to reproduce the problem.


HARDWARE:
Intel P4 with hyper-threading enabled
Realtek 8169 (rev. 10)
Switched 100Mbps network
A second machine on the same network (to receive test packets)

SOFTWARE:
Kernel 2.6.0 or 2.6.1-rc1 (possibly others), with SMP for 2 processors,
Realtek 8169 driver, and packet generator


STEPS TO REPRODUCE:
1.) Set up the ipg script to send to the second machine on the 8169 NIC.
2.) pgset pkt_size 9014
3.) pg


OBSERVATIONS:
Soon after step #3, the 8169 NIC will stop responding (note: the netdev
watchdog reports a timeout in dmesg).  No packets get through.  However,
everything else still works.  Disabling SMP in the kernel fixes this
problem.



Doug.