[e2e] Re: UDP Performance problem

Kartik Gopalan kartik at cs.fsu.edu
Thu Feb 10 16:58:47 PST 2005

You might want to check if the particular model of your SMC switch 
supports jumbo frames in the first place -- most lower-end Gigabit 
switches in market don't. We get up 700 to 900Mbps with UDP on SMC8508T 
switches and Intel PRO/1000 NIC cards (depending on the interrupt 
coalescing value set on the NIC). My colleague has reported between 450 to 
600Mbps with TCP.

You may also need to pace the sending rate a little from your UDP 
application to achieve peak throughput, so that your NIC doesn't get 
overwhelmed and start randomly dropping packets.

- Kartik

> From: sahans at cse.mrt.ac.lk
> Subject: [e2e] UDP Performance problem
> To: end-to-end list <end2end-interest at postel.org>
> Message-ID: <1108030135.420b32b7399b1 at mail.mrt.ac.lk>
> Content-Type: text/plain; charset=ISO-8859-1

> Hi,
> I am writing a a networking library to facilitate faster data transfers 
> using UDP. The required level of performance is 120Mbps (at the minimum) 
> on Gigabit Ethernet. But at the moment what I am getting is around 
> 32Mbps. I am using a 8kB packet size and using Redhat 2.4.21 kernel 
> (Enterperise Linux). I am having 4X 2.8GHz Intel Xeon CPUs with 4GB 
> memory. Two identical machines are interconnected using an SMC switch 
> (Gigabit Ethernet) Does anybody has an idea about this dissapoiniting 
> performance?
> Thanks in advance
> Sahan

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