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

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Revision 1.6 - (hide 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 cnh 1.6 C $Header: /u/u0/gcmpack/MITgcm/eesupp/inc/BARRIER.h,v 1.5 2004/03/27 03:51:50 edhill Exp $
2 cnh 1.4 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 edhill 1.5 C | CALL FBAR\_INIT
26 cnh 1.4 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 edhill 1.5 C | on CRAY, NEC FBAR will just do C\$DIR BARRIER
34 cnh 1.4 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 cnh 1.1 COMMON / BARRIER_COMMON / key1, key2, key3,
40 cnh 1.6 & door1, door2, door3,
41     & bCount
42 cnh 1.1 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 cnh 1.6 INTEGER bCount(MAX_NO_THREADS)

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