[gmx-users] Parallel Gromacs Benchmarking with Opteron Dual-Core & Gigabit Ethernet

Yang Ye leafyoung at yahoo.com
Tue Jul 24 15:48:28 CEST 2007

On 7/24/2007 5:16 PM, Erik Lindahl wrote:
> Hi,
>> I agree with you about the GbE sharing between 4 cores degardes the
>> performance. Fortunately, every Cluster node has two GbE ports. I
>> want to know, can I configure lamd in such a manner that every processor
>> on every node (with two cores) uses one of these ports for its
>> communication purposes? And if this is possible, could you please 
>> give me
>> some hints or guidance to start this configuration on the cluster?
>> And finally, can you expect any scalability improvements by taking this
>> approach?
> Built-in network cards are usually of lower quality, so there's 
> probably only a single processor controlling both ports, and since the 
> card probably only has a single driver requests might even be serialized.
> If you have lots of available ports on your gigabit switches and both 
> switches+cards support "port trunking" you could try to connect two 
> cables to each node and get a virtual 2Gb bandwidth connection. For 
> more advanced stuff you'll have to consult the lam-mpi mailing list, 
> although I'd be (quite pleasantly) surprised if it's possible to tweak 
> gigabit performance a lot!
I used this in our cluster. It's call bonding in some places. Redhat has 
documented it for its Enterprise Linux (docs are freely available) And 
there are a lot to be found.
> Cheers,
> Erik
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