Network Performace

Karl Pielorz kpielorz at
Wed Jun 25 01:16:29 PDT 2003

--On 24 June 2003 17:01 -0700 Shawn Ramsey <shawn at> wrote:

>> Try looking into FreeBSD's "polling" mode - i.e. interrupt free Network
>> cards. If your shifting a lot of small packets (such as online gaming
>> stuff  etc.) - you may find your milage pretty limited using standard PC
>> kit - as  the x86 architecture wasn't really designed for shifting lots
>> of small  packets around [as I've seen many a time in the past :(]
> This router is routing 99% NNTP traffic, so I wouldn't think small packet
> size would be it. I tried polling, and its greatly increased the amount of
> "idle CPU", and Interupt is around 20% now...

That's certainly a step in the right direction :)

> But something is still very
> wrong performance wise. It has helped, but I still can't push in/out
> nearly 100Mb/sec. (100Mb in, 100Mb out I mean). A simple FTP transfer
> locally through the routers gigabit interface causes our internet
> performance to plummet. I've disabled all the onboard stuff that was
> sharing IRQs with PCI cards, but I didn't figure that was an issue,
> didn't make a difference either way. Would the fact the gigabit is on the
> same PCI bus have any bearing? I would expect to at least get 100BT
> performance even so, but I don't have any experience with gigabit
> ethernet...

The only thing I can suggest is try different PCI slots, or Gigabit cards, 
or, worst case a different system. Having NIC's on separate PCI busses (as 
opposed to both on the same PCI bus) may help it [But that's probably going 
to need a new board etc.]

You don't say what Gigabit nic's your using? - I've had a lot of varied 
results with different nic's, with surprisingly cheap 10/100/1000Mbit cards 
giving 'reasonable' performance - but get left standing for dust by other 
more expensive cards.

The only other thing I can think of is, check the duplex/media options are 
all setup properly on the cards / switches etc. - or try forcing things to 
fdx etc.


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