2.2.1 TCP & IRIX 6.x

Ben Ross (ben@proximity.com.au)
Thu, 18 Feb 1999 18:54:56 +1100 (EST)


I have recently seen a very noticable TCP performance drop transferring
files (via FTP) from an SGI (both Indy & O2 running IRIX 6.x) to a machine
running Linux 2.2.1. In the IRIX -> Linux direction the speed seems to be
limited to a maximum of about 80Kb/s (over an ethernet) whereas in the
other direction, the speed is what one would expect (given the hardware in
the Linux machine). This situation does not occur between 2.0.x kernels
and IRIX (with the same hardware on the Linux end), nor between a machine
with 2.2.1 and another with 2.0.36.

I have yet to try a different ethernet card in the Linux machine, however
since the situation only occurs between IRIX & 2.2.1 and not
2.0.x <-> 2.2.1, I suspect it might be something other than the ethernet
driver.

It's hard to tell which end the problem is occuring. It's possible that
something is causing the TCP connection to incorrectly throttle down to a
slower speed. I would like to try and debug this further since I have
access to this mix of equipment, but I was hoping I might get some insight
on how to go about it and what to look for (possibly from a tcpdump
session).

Anyway, the problem was alarming enough for me to post it here and it
would be good if someone could try and reproduce it under similar
circumstances.

PS, I am not subscribed to this mailing list but will do so if necessary.

Regards,
Ben

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| \- -/ ben@proximity.com.au \` '/ |
| \|/ http://www.proximity.com.au/~ben/ \~/ |
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