Cap on network speed in CURRENT?

Luke luked at
Tue Jun 1 19:12:24 PDT 2004

>>>> I've got a 100Mbps LAN with ethernet cards that should be capable of using
>>>> it, yet the highest transfer rates I seem to be able to get out of my
>>>> FreeBSD box are 260KB/s receiving and 341KB/s sending with around 200KB/s
>>>> being more normal.
>>> On a LAN, buffer size has minimal effect except at very high speeds.
>>> Without tuning, two 5.x boxes with gigabit interfaces connected to a
>>> Cisco 6513 switch (one 5/10/04 and one 2/20/04) reached 187Mbps in
>>> iperf.  You're problems symptoms sound like duplex mismatch or bad
>>> hardware to me.
>> I've forced both full and half duplexing and gotten the same results both
>> ways.  I certainly won't rule out bad hardware.  I just don't know how to
>> troubleshoot this.
>> Would disabling "witness" help?  I've read that "witness" can slow down
>> some things, but I don't know if network speed is one of them.
> WITNESS definatly slows things down, but not that much.  The machines I
> gave results from are running with WITNESS enabled.  How are you testing
> your bandwidth?  If you aren't you should be using netperf, iperf, ttcp,
> or similar.  Not that any other method I can think of would account for
> this much slowness unless you've got really slow hosts.

I'm using the "bmon" utility while transferring files over a samba share, 
bacula's built-in speed reporting while running backups, and the little 
green "utilization %" indicator lights on my hub while doing each of 
those things....
I guess these are not the best speed indicators, but they're all coming up 
with the same numbers.

This is indeed a very slow host, by modern standards.  It's a fussy old 
Pentium 166MHz that I've put through hell for the last eight years or so.

I'm building a kernel with witness and invariants turned off.  Building a 
kernel usually takes overnight.  I'll try it out tomorrow and see how it 
goes.  If those testing programs don't require X, I'll see about 
installing one of them to help me figure out what's going on.  The iperf 
site looks like it's got some helpful information that I should read too.

Thanks for the assistance.

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