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C $Header: /u/gcmpack/MITgcm/eesupp/inc/GLOBAL_SUM.h,v 1.7 2007/09/04 14:41:24 jmc Exp $ |
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C $Name: $ |
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CBOP |
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C !ROUTINE: GLOBAL_SUM.h |
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C !INTERFACE: |
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C include "GLOBAL_SUM.h" |
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C !DESCRIPTION: |
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C *==========================================================* |
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C | GLOBAL\_SUM.h |
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C | o Globals used by Fortran global sum routine. |
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C *==========================================================* |
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C | The global sum shared memory scheme uses global heap data| |
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C | structures (.i.e COMMON blocks ). Each thread writes to | |
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C | an its own element of the shared memory array and then | |
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C | one thread reads all the entries and sums them. The sum | |
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C | result is then read by all threads. | |
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C | Remember - you are working with regions of memory that | |
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C | are being updated concurrently by different threads. | |
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C | What happens, when it happens and who gets to see what | |
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C | happens at what stage depends on the computer systems | |
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C | memory model. Every computer has a different memory model| |
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C | and they are never simple. In all current platforms it is| |
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C | possible for one thread to see events happening in a | |
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C | different order from the order they are written in the | |
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C | code. | |
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C | Unless you understand this it is not a good idea to | |
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C | make modifications te way these header files are setup or| |
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C | the way the global sum routines work. | |
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C *==========================================================* |
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CEOP |
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|
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COMMON / GSUM_COMMON_R8 / phiGSR8, shareBufGSR8 |
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c & , phiVGSR8 |
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Real*8 phiGSR8 (lShare8, 0:MAX_NO_THREADS ) |
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Real*8 shareBufGSR8 ( nSx, nSy ) |
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c Real*8 phivGSR8(MAX_VGS, 0:MAX_NO_THREADS ) |
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|
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COMMON / GSUM_COMMON_R4 / phiGSR4 |
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c & , phiVGSR4 |
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Real*4 phiGSR4 (lShare4, 0:MAX_NO_THREADS ) |
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c Real*4 phivGSR4(MAX_VGS, 0:MAX_NO_THREADS ) |
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|
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COMMON / GSUM_COMMON_I / phiGSI |
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c & , phiVGSI |
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INTEGER phiGSI (lShare4, 0:MAX_NO_THREADS ) |
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c INTEGER phivGSI (MAX_VGS, 0:MAX_NO_THREADS ) |
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|
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CEH3 ;;; Local Variables: *** |
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CEH3 ;;; mode:fortran *** |
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CEH3 ;;; End: *** |
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