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I'm quite new to HPC environment. Is there any difference in running a job on a node utilizing 8 cores and running the same job on 8 nodes utilizing I core in terms of performance or walltime used.

PS: I'm working on a project which involves running a script in the cluster which takes around 2-3 days for the output. Hence such a doubt to avoid irrelevant tests.

slm
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Ashwin
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  • It mostly depends on how much your processes need to talk to _each other_. Even Infiniband is going to be slower than a connection purely local to a node. – Michael Hampton Aug 30 '13 at 03:19

1 Answers1

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Probably, yes. It's hard to tell which will be faster though because there are a lot of factors. If possible, run a smaller version of your program so that you can compare both. Here are some factors that affect performance:

  • Interprocess communication (as Michael mentioned in his comment): Communication between cores on the same node is faster than Infiniband.
  • Resource competition: Processes/threads running on the same node must share resources like I/O (disk and network) and memory.

If this is a CPU-bound application and you have 8 nodes available, you might consider using all 64 cores.

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