/[MITgcm]/MITgcm/eesupp/inc/BARRIER.h
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Contents of /MITgcm/eesupp/inc/BARRIER.h

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Revision 1.6 - (show annotations) (download)
Mon Nov 7 18:16:07 2005 UTC (18 years, 5 months ago) by cnh
Branch: MAIN
Changes since 1.5: +4 -2 lines
File MIME type: text/plain
Changes that enable OpenMP based threads.
Note - not all compute code is compatible with these.

1 C $Header: /u/u0/gcmpack/MITgcm/eesupp/inc/BARRIER.h,v 1.5 2004/03/27 03:51:50 edhill Exp $
2 C $Name: $
3 CBOP
4 C !ROUTINE: BARRIER.h
5 C !INTERFACE:
6 C include "BARRIER.h"
7 C !DESCRIPTION:
8 C *==========================================================*
9 C | BARRIER.h
10 C | o Globals used by Fortran barrier routine.
11 C *==========================================================*
12 C | These variables support a simple Fortran shared memory
13 C | barrier routine. They do busy waiting, that is the
14 C | thread that is waiting sits in a tight loop reading
15 C | some memory location and waiting for all other threads.
16 C | On some systems this is sometimes a good method to use.
17 C | On the T3E memory is not shared so the routine should
18 C | use the T3E "eureka" barriers. On CRAY and NEC there are
19 C | hardware barriers that are accessed through a compiler
20 C | directives. Finally proper multi-threading compilers
21 C | support barrier compile directives - sometimes these
22 C | are good, sometimes they are lousy.
23 C | The barrier mechanism is used as follows
24 C | 1. In the single-threaded part of the code
25 C | CALL FBAR\_INIT
26 C | on CRAY, NEC this routine does nothing
27 C | on T3E there is no single-threaded code
28 C | but there may be barrier initialisation -
29 C | need to check.
30 C | 2. When we need to synchronize everybody just
31 C | CALL FBAR( myThid )
32 C | where myThid is myThreadId
33 C | on CRAY, NEC FBAR will just do C\$DIR BARRIER
34 C | or the like.
35 C | on T3E FBAR does CALL BARRIER(...) or something
36 C | need to check this.
37 C *==========================================================*
38 CEOP
39 COMMON / BARRIER_COMMON / key1, key2, key3,
40 & door1, door2, door3,
41 & bCount
42 INTEGER key1(lShare4,MAX_NO_THREADS)
43 INTEGER key2(lShare4,MAX_NO_THREADS)
44 INTEGER key3(lShare4,MAX_NO_THREADS)
45 INTEGER door1
46 INTEGER door2
47 INTEGER door3
48 INTEGER VALID
49 PARAMETER ( VALID = 1 )
50 INTEGER INVALID
51 PARAMETER ( INVALID = 0 )
52 INTEGER OPEN
53 PARAMETER ( OPEN = 1 )
54 INTEGER SHUT
55 PARAMETER ( SHUT = 0 )
56 INTEGER bCount(MAX_NO_THREADS)

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