[nycbug-talk] TCP tuning between FreeBSD and Vista

Steven Kreuzer skreuzer at exit2shell.com
Mon Nov 3 09:07:49 EST 2008

On Nov 2, 2008, at 2:19 PM, Alex Pilosov wrote:

> On Sun, 2 Nov 2008, Jonathan wrote:
>> I've been playing with it for two days and I can't for the life of me
>> get more than 7% utilization of a gigabit link between my laptop  
>> and my
>> file server.  I've gone through man tuning as well as a great deal of
>> Google searching and here are the settings I've tried tweaking with
>> their current values.  My current testing is transmitting from  
>> FreeBSD
>> to Vista so I've not messed with receive specific settings on BSD  
>> or the
>> transmit specific on Vista.
> 99% chance that either
> a) you have a duplex issue (check netstat -i)
> b) it's not gigabit.

At work we were recently testing some new network equipment and out of  
every piece of
equipment we tested, only one of them managed to deliver on the full  
capacity of the link.
When the interface was brought up, it would negotiate at the full  
speed, but we would usually
only get 50% utilization on average.

Another reason might be the method you are using to do your tests.  
Since you said this was
a file server, are you just copying a file from Vista to FreeBSD? If  
so, you'll also have to look to
see if the hard drive is the bottleneck (Chances are that it is). If  
this is your testing methodology,
I would take a look at using something like tcppref.

Another possibility is that the controller your hard drive is  
connected to shares the same PCI bus that you
have your NIC in and they are sharing interrupts. If at all possible,  
it's usually better to not share.


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