bad TCP performance

Alexander V. Mirgorodsky mirg@ccas.ru
Tue Mar 2 04:12:16 1999


I'm observing really bad TCP performance in Linux 2.2.x <-> Linux 2.2.x
interaction:

We have a switched 100Mbit network of identical PII 266 boxes equipped
with eepro100+ cards and the problem is as follows:

ttcp: 2.0.32   <-> 2.0.32    10Mb/s
ttcp: 2.2.2    <-> 2.0.32    10Mb/s
ttcp: 2.2.2    <-> 2.2.2     400Kb/s - in this case lots of frame errors
are produced (~ 1 error/packet)

Version of eepro100 doesn't matter much - fixing  eepro100-0.99B to work
with 2.2.2 (which has eepro100-1.06) produces the same results.

Changing sockbufsize doesn't help a lot. ( +- 100k/s)

Other tcp based programs behave the same way.

UDP performance is around 11Mb/s in each case

These effects are 100% reproducible so I can probably debug the
situation if someone points me in right direction :)

Regards, Alexander.