System hang with heavy network traffic using rtl8139c

[R. Steve McKown]

Hi -

We have a multi-threaded load test program that will cause any x86 
system configuration upon which we've tried that that contains at least 
one rtl8139c to hard lock the system.  The exact same OS image and test 
program has been shown to run on several exact same configurations by 
simply replacing the rtl8139c device(s) with intel 82559ER's or Digital 
21143TD's.  Please read on for more info.

I am involved in reliability testing of our linux-based network device 
with which we plan to use realtek 8139c parts as its three main network 
interfaces.  The system is architecturally very much like an x86 PC and 
runs a standard linux 2.4.16 kernel with some well-used community 
patches and/or driver modules.

We created a multi-threaded test program that generates bidirectional 
traffic over all network interfaces simultaneously as fast as possible. 
 Using this test, the system will lock up hard, taking from 90 seconds 
to 1.5 weeks to do so.  Most failures occur, however, within the 2-5 
hour range.  The lock-up is complete, in that not even sysrq works. 
 More typical network traffic patterns do not cause lockups.  In 
general, the test configurations have between 4 and 8 network devices 
installed in the system, with most tests running with 8 devices.  No 
test has used more than 4 devices of any single chipset.

We have ran our test on various hardware configurations to narrow the 
problem boundaries, and the results are always the same: if the 
configuration includes a RealTek 8139C part it will lock up.  If it 
contains *no* 8139C it will not.

We can duplicate this behaviour on our hardware using either Geode GX1 
processors or Transmeta Crusoe TM5800 processors.  We can duplicate it 
on desktop Pentium MMX-based systems that contain none of our hardware. 
 Realtek configurations lock up regardless of which driver we are using 
(rtl8139 v1.18 / pci-scan v1.08 or 8139too v0.9.22).  With any 
configuration, replacing the rtl parts with intel (82559ER) or digital 
(21143TD) and the system will not fail.  The reverse has also been true. 
Mixed-part environments fail even with a single rtl part installed, but 
will not if there are no rtl parts.

I'm hoping to get some feedback from some of you out there who have 
worked with this part more than I.  I'll be happy to post specifics as 
requested.  I also appreciate thoughts on how to debug this problem 
given that it fully locks up the system.

I have posted this message to LKML and to the realtek ML, so reply 
accordingly.

All the best,
R. Steve McKown
Titanium Mirror, Inc.