Changes between Version 125 and Version 126 of doc/app/initialization_parameters


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Timestamp:
Oct 20, 2010 1:32:08 PM (14 years ago)
Author:
gryschka
Comment:

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  • doc/app/initialization_parameters

    v125 v126  
    536536'''Note:'''\\
    537537In some cases for small processor numbers there may be a very bad load balancing among the processors which may reduce the performance of the code.
    538 }}}
    539 |----------------
    540 {{{#!td style="vertical-align:top"
    541 [=#npex '''npex''']
    542 }}}
    543 {{{#!td style="vertical-align:top"
    544 I
    545 }}}
    546 {{{#!td style="vertical-align:top"
    547 
    548 }}}
    549 {{{#!td
    550 Number of processors along x-direction of the virtual processor net.\\\\
    551 For parallel runs, the total number of processors to be used is given by the '''mrun'''-option -X. By default, depending on the type of the parallel computer, PALM generates a 1d processor net (domain decomposition along x, [#npey npey] = ''1'') or a 2d-net (this is favored on machines with fast communication network and/or large number of processors (>256)). In case of a 2d-net, it is tried to make it more or less square-shaped. If, for example, 16 processors are assigned (-X 16), a 4 * 4 processor net is generated ('''npex''' = 4, '''npey''' = 4). This choice is optimal for square total domains ([#nx nx] = [#ny ny]), since then the number of ghost points at the lateral boundarys of the subdomains reaches a minimum. If nx and ny differ extremely, the processor net should be manually adjusted using adequate values for '''npex''' and '''npey'''.\\\\
    552 '''Important:'''\\
    553 The value of '''npex''' * '''npey''' must exactly match the value assigned by the '''mrun'''-option -X. Otherwise the model run will abort with a corresponding error message.\\\\
    554 Additionally, the specification of '''npex''' and '''npey''' may of course override the default setting for the domain decomposition (1d or 2d) which may have a significant (negative) effect on the code performance.
    555 }}}
    556 |----------------
    557 {{{#!td style="vertical-align:top"
    558 [=#npey '''npey''']
    559 }}}
    560 {{{#!td style="vertical-align:top"
    561 I
    562 }}}
    563 {{{#!td style="vertical-align:top"
    564 
    565 }}}
    566 {{{#!td
    567 Number of processors along y-direction of the virtual processor net.\\\\
    568 For further information see [#npex npex].
    569538}}}
    570539|----------------