Optimization modes

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Jaakko Leppänen
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Optimization modes

Post by Jaakko Leppänen » Fri Feb 03, 2012 12:27 pm

The optimization modes that affect code performance and memory usage are controlled by option:

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set opti <mode>
where <mode> is the optimization mode 1 - 4. You can find some background information on this topic in my presentation at the Dresden meeting:

http://montecarlo.vtt.fi/mtg/2011_Dresd ... panen2.pdf

I will also present a paper in PHYSOR-2012. In summary, the modes are (from my PHYSOR-paper):

Mode 4: Maximum performance at the cost of memory usage. Suitable for group constant generation and 2D assembly burnup calculations with a limited number of depletion zones. The methodology is essentially the same as that used in Serpent 1.

Mode 3: Similar to mode 4, but lower memory demand. CPU time required by burnup and processing routines increases steeply along with the number of depletion zones, which makes the mode better suited for small burnup calculation problems.

Mode 2: Good performance in burnup calculations involving several thousand depletion zones. Suitable for research reactor applications, but not the best choice for group constant generation.

Mode 1: Minimum optimization and small memory usage. Suitable for very large burnup calculation problems involving tens or hundreds of thousands of depletion zones.

Default is mode 4, and it is pretty much the same as Serpent 1. For large burnup calculation problems I suggest you try mode 1 or 2. Mode 2 reduces memory usage per burnable material, and mode 1 minimizes everything. Mode 3 is usable with small burnup calculation problems in machines with very limited memory.
- Jaakko

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