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Metis and parallel computing in Tough

Hi All,

  I found many descriptions about Metis in the User's guide of Tough2-MP. However, there is little description of Metis in Tough3. So, is Metis used in Tough3 for parallel computing? Moreover, I tested the eco2m module using the Infile in the rwaf folder of the Samples folder. Compared to a single core (1600s), the speedup  of a dual core can reach 2 (800s), but when using a 3-core, the calculation time actually reaches 4400s, which is much slower than when using a single core. What is the reason for this? Thank you very much.

Yong

2 replies

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    • kenny
    • 1 yr ago
    • Reported - view

    The parallel computing scheme inside TOUGH3 is identical to the TOUGH2-MP. It still uses Metis for domain decomposition. There are many reasons that can lead to worse performance with using more cores, such as communication overload for small model, competition for computing resource ( computing resource shared with other applications), and worse convergence behavior after domain decomposition with more subdomains. 

      • Yong.1
      • 1 yr ago
      • Reported - view

       Thank you, Kenny. I checked the output file. The worse performance is due to the worse convergence behavior after domain decomposition (the linear solver time is much longer for the case of 3 cores). Based on your experience, is there a method to avoid this situation, as we have no way to know if it will cause this situation when conducting parallel computing. Thanks.

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