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C $Header: /u/u0/gcmpack/MITgcm/eesupp/inc/BARRIER.h,v 1.5 2004/03/27 03:51:50 edhill Exp $ |
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C $Name: $ |
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CBOP |
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C !ROUTINE: BARRIER.h |
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C !INTERFACE: |
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C include "BARRIER.h" |
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C !DESCRIPTION: |
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C *==========================================================* |
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C | BARRIER.h |
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C | o Globals used by Fortran barrier routine. |
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C *==========================================================* |
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C | These variables support a simple Fortran shared memory |
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C | barrier routine. They do busy waiting, that is the |
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C | thread that is waiting sits in a tight loop reading |
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C | some memory location and waiting for all other threads. |
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C | On some systems this is sometimes a good method to use. |
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C | On the T3E memory is not shared so the routine should |
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C | use the T3E "eureka" barriers. On CRAY and NEC there are |
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C | hardware barriers that are accessed through a compiler |
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C | directives. Finally proper multi-threading compilers |
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C | support barrier compile directives - sometimes these |
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C | are good, sometimes they are lousy. |
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C | The barrier mechanism is used as follows |
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C | 1. In the single-threaded part of the code |
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C | CALL FBAR\_INIT |
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C | on CRAY, NEC this routine does nothing |
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C | on T3E there is no single-threaded code |
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C | but there may be barrier initialisation - |
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C | need to check. |
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C | 2. When we need to synchronize everybody just |
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C | CALL FBAR( myThid ) |
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C | where myThid is myThreadId |
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C | on CRAY, NEC FBAR will just do C\$DIR BARRIER |
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C | or the like. |
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C | on T3E FBAR does CALL BARRIER(...) or something |
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C | need to check this. |
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C *==========================================================* |
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CEOP |
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COMMON / BARRIER_COMMON / key1, key2, key3, |
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& door1, door2, door3, |
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& bCount |
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INTEGER key1(lShare4,MAX_NO_THREADS) |
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INTEGER key2(lShare4,MAX_NO_THREADS) |
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INTEGER key3(lShare4,MAX_NO_THREADS) |
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INTEGER door1 |
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INTEGER door2 |
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INTEGER door3 |
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INTEGER VALID |
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PARAMETER ( VALID = 1 ) |
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INTEGER INVALID |
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PARAMETER ( INVALID = 0 ) |
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INTEGER OPEN |
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PARAMETER ( OPEN = 1 ) |
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INTEGER SHUT |
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PARAMETER ( SHUT = 0 ) |
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INTEGER bCount(MAX_NO_THREADS) |
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