3c905 network pauses with 2.2.x

Chris Adams (cadams@ro.com)
Sun, 11 Apr 1999 14:08:52 -0500


I have a Compaq Proliant news server (PPro 200, 320 MB RAM, DPT
SmartRAID IV SCSI). It has 2 ethernet interfaces: the built-in TI TLAN
(eth1) and a 3Com 3c905 (eth0), both running at 10Mb/s. The news feeds
come in through eth1 and the readers use eth0.

I decided to try a 2.2 kernel because under 2.0.3[4-6], I get sporadic
crashes in ip_rt_expire after an uptime between a few hours and a week.
This is a mostly Red Hat 4.2 machine, but I upgraded the necessary
packages according to Documentation/Changes.

I tried 2.2.5 and 2.2.5-ac6, and I don't get the crashes, but the 3Com
network interface experiences pauses where I don't get any packets
through it for 1-10 seconds (I get 8-30% packet loss when I run ping for
a while). Thinking that maybe the 3Com driver in 2.2.5 was the problem,
I recompiled with the 3Com driver from 2.0.36, but I still see the same
problem.

It only seems to do this when the system is under a load - if INN isn't
running, it doesn't seem to happen. The TI interface doesn't seem to
have this problem (if I run a ping on the news server to a device out
the TI interface I don't see any packets lost).

I say it seems to happen under load, but it doesn't happen at the moment
the server is busy. If I run "vmstat 1" for a while, the pauses are NOT
when the system is most busy. I als compiled in the patch included with
sard and ran it with a 1 second update, and the pauses aren't when the
disk is most busy either.

But if INN isn't running (and taking up a lot of RAM and using a lot of
disk I/O), I don't see the pauses.

Has anyone seen anything like this? Any suggestions? If there is any
more info I can provide, please let me know.

-- 
Chris Adams <cadams@ro.com> - System Administrator
Renaissance Internet Services - IBS Interactive, Inc.
Home: http://ro.com/~cadams - Public key: http://ro.com/~cadams/pubkey.txt
I don't speak for anybody but myself - that's enough trouble.

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