It looks like there is a problem with realtek 8139
under heavy load: While performing concurrent max.
rate downloads (on a system with slow disk i/o reason
unknown) the nic simply hangs after a few secs. The
systems continues to run, ifdown / ifup brings the nic
We can reproduce this problem on all of our systems
that use 8139 cards (kernel 2.2.19 (running the old
8139 module) and 2.4.5). Here is how we do it:
Machine a) some IDE machine with realtek card
Machine b) Some other machine running a webserver and
a providing large file for download
a) and b) are connected to each other via 100Mbit
(switched in our case)
- turn dma mode off for all drives in machine a
(hdparm -d0 /dev/hda ...). this is a necessary step to
provoke the problem.
- run "wget http://machine.b/bigfile &" about 10 times
- network of machine a) will hang after a few secs
- after replacing nic in machine a) with a different
non-realtek nic (we used 3com) the same test will not
hang the network.
IMHO this could mean that the problem occurs when the
nics buffer overruns but you are the experts here ;-)
It is possible that this is a generic problem with the
8139 and not linux-related.
We have once seen an error-message like "frame too
large" while testing this on different machines, it
only showed up in about 1/100 of our testruns.
I will gladly help if you have trouble reproducing
this problem, we were able to reproduce it with PCI-
Adapters as well as with on-mainboard Realtek 8139
Please contact me if any questions arise.
(replace //at// with @)