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]. |