[Beowulf] Slection from processor choices; Requesting Giudence

[Vincent Diepeveen]

As i'm not a complete layman in fluid dynamics software i'll make a few assumption to advice a choice:

assumptions:
a) that gigabit is enough for you and that you don't need bandwidth to other nodes
b) that you are interested in having a huge amount of RAM at each compute nodes
c) that price is important as you probably want to put there a lot of nodes
d) that your code usually runs single cpu and uses all RAM

In that case perhaps an idea is getting a new dual opteron mother board and put inside
a single core opteron 2.6Ghz or 2.8Ghz if they are there. That's unbeatable in terms of
latency to RAM.

Those new boards sometimes support up to 16 DIMMs. That might be very interesting for you.

If you put in 2x166Mhz (PC333) 2GB dimms * 16 ecc registered CL2 = 32GB.

That will be faster for you than PC3200 (as it might get clocked back to pc2700 anyway) cl 2.5
for latency. 

Probably this is very interesting for you. At least 1 manufacturer i saw (tyan) has a dual opteron board that
supports 16 DIMMs. Perhaps there is others manufacturers which offer 16 dimms. I can't recall
manufacturers offering more DIMMs than that.

Perhaps certain quad boards do?

Note that there is 1 solution not so cheap that offers 32 DIMMs. That's creating a 8 core machine.
Iwill and Tyann should both have a solution there. 

Put in cheap single core 8xx chips (which are there especially at ebay cheap as everyone wants to
get rid of them and get dual cores for codes that need the cpu speed instead of huge RAM).
And fill it with 32 DIMMs PC2700. That would give 1 compute node a 64GB ram.

I'm not sure whether pc2700 cl2 or pc3200 cl2.5 is faster in latency at those quads. 

Could be pc3200 cl2.5 wins it there. It's a lot more expensive though.

Good luck,
Vincent


  ----- Original Message ----- 
  From: amjad ali 
  To: beowulf at beowulf.org 
  Sent: Thursday, June 15, 2006 9:02 AM
  Subject: [Beowulf] Slection from processor choices; Requesting Giudence


  Hi ALL

  We are going to build a true Beowulf cluster for Numerical Simulation of Computational Fluid Dynamics (CFD) models at our university. My question is that what is the best choice for us out of the following choices about processors for a given fixed/specific amount/budget:

    1.. One processor at each of the compute nodes

    2.. Two processors (on one mother board) at each of the compute nodes

    3.. Two Processors (each one dual-core processor) (total 4 cores on the board) at each compute nodes.

    4.. four processor (on one mother board) at each of the compute nodes.




  Initially, we are deciding to use Gigabit ehternet switch and 1GB of RAM at each node. 

  Please guide me that how much parallel programming will differ for the above four choices of processing nodes.


  with best regards:
  Amjad Ali.




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