[e2e] UDP Performance problem

sahans at cse.mrt.ac.lk sahans at cse.mrt.ac.lk
Thu Feb 10 07:22:54 PST 2005

> TCP should be able to do that without difficulty.  Why use UDP???
Final implementation will be multicast based one. We have higher data rates
(transefer rate * no. of hosts) that point-to-point cannot achive even in
10Gbps infiniband.

For the second issue .. I am just sending udp datagrams and and just increment a
counter at the clientside on the recipt of data. I am not sure about the other
parameters ..  but I am having doubts about 10ms Linux timeslice ...


Quoting Craig Partridge <craig at aland.bbn.com>:

> >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. 
> TCP should be able to do that without difficulty.  Why use UDP???
> >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)
> Not clear you've provided enough information here, particularly if you're
> send back acks for the UDP datagrams.  Let's assume, for a moment, that
> this is a naive implementation and you're just sending UDP packets as fast
> as you can.
> You're sending or receiving a packet roughly every 65 us.  How fast can
> your machine take interrupts?  How fast can it copy memory through the
> processor?  In short, what's your time budget and does it fit within
> 65us.  (My rough estimate says it may be close -- 60ns DRAM with 16-byte
> chunks [128 bit bus] takes at least 30us to copy 8kB...)
> Craig

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