eesupp/inc/BARRIER.h

C $Header: /u/gcmpack/models/MITgcmUV/eesupp/inc/BARRIER.h,v 1.2 1998/04/23 20:59:34 cnh Exp $
C $Name: $
C
C     /==========================================================\
C     | FBAR.h                                                   |
C     | o Globals used by Fortran barrier routine.               |
C     |==========================================================|
C     | These variables support a simple Fortran shared memory   |
C     | barrier routine. They do busy waiting, that is the       |
C     | thread that is waiting sits in a tight loop reading      |
C     | some memory location and waiting for all other threads.  |
C     | On some systems this is sometimes a good method to use.  |
C     | On the T3E memory is not shared so the routine should    |
C     | use the T3E "eureka" barriers. On CRAY and NEC there are |
C     | hardware barriers that are accessed through a compiler   |
C     | directives. Finally proper multi-threading compilers     |
C     | support barrier compile directives - sometimes these     |
C     | are good, sometimes they are lousy.                      |
C     |  The barrier mechanism is used as follows                |
C     |  1. In the single-threaded part of the code              |
C     |     CALL FBAR_INIT                                       |
C     |     on CRAY, NEC this routine does nothing               |
C     |     on T3E there is no single-threaded code              |
C     |        but there may be barrier initialisation -         |
C     |        need to check.                                    |
C     |  2. When we need to synchronize everybody just           |
C     |     CALL FBAR( myThid )                                  |
C     |     where myThid is myThreadId                           |
C     |     on CRAY, NEC FBAR will just do C$DIR BARRIER         |
C     |     or the like.                                         |
C     |     on T3E FBAR does CALL BARRIER(...) or something      |
C     |     need to check this.                                  |
C     \==========================================================/
      COMMON / BARRIER_COMMON / key1,  key2,  key3, 
     &                          door1, door2, door3
      INTEGER key1(lShare4,MAX_NO_THREADS)
      INTEGER key2(lShare4,MAX_NO_THREADS)
      INTEGER key3(lShare4,MAX_NO_THREADS)
      INTEGER door1
      INTEGER door2
      INTEGER door3
      INTEGER VALID
      PARAMETER ( VALID = 1 )
      INTEGER INVALID
      PARAMETER ( INVALID = 0 )
      INTEGER OPEN
      PARAMETER ( OPEN = 1 )
      INTEGER SHUT
      PARAMETER ( SHUT = 0 )
1	C $Header: /u/gcmpack/models/MITgcmUV/eesupp/inc/BARRIER.h,v 1.2 1998/04/23 20:59:34 cnh Exp $
2	C $Name: $
3	C
4	C /==========================================================\
5	C \| FBAR.h \|
6	C \| o Globals used by Fortran barrier routine. \|
7	C \|==========================================================\|
8	C \| These variables support a simple Fortran shared memory \|
9	C \| barrier routine. They do busy waiting, that is the \|
10	C \| thread that is waiting sits in a tight loop reading \|
11	C \| some memory location and waiting for all other threads. \|
12	C \| On some systems this is sometimes a good method to use. \|
13	C \| On the T3E memory is not shared so the routine should \|
14	C \| use the T3E "eureka" barriers. On CRAY and NEC there are \|
15	C \| hardware barriers that are accessed through a compiler \|
16	C \| directives. Finally proper multi-threading compilers \|
17	C \| support barrier compile directives - sometimes these \|
18	C \| are good, sometimes they are lousy. \|
19	C \| The barrier mechanism is used as follows \|
20	C \| 1. In the single-threaded part of the code \|
21	C \| CALL FBAR_INIT \|
22	C \| on CRAY, NEC this routine does nothing \|
23	C \| on T3E there is no single-threaded code \|
24	C \| but there may be barrier initialisation - \|
25	C \| need to check. \|
26	C \| 2. When we need to synchronize everybody just \|
27	C \| CALL FBAR( myThid ) \|
28	C \| where myThid is myThreadId \|
29	C \| on CRAY, NEC FBAR will just do C$DIR BARRIER \|
30	C \| or the like. \|
31	C \| on T3E FBAR does CALL BARRIER(...) or something \|
32	C \| need to check this. \|
33	C \==========================================================/
34	COMMON / BARRIER_COMMON / key1, key2, key3,
35	& door1, door2, door3
36	INTEGER key1(lShare4,MAX_NO_THREADS)
37	INTEGER key2(lShare4,MAX_NO_THREADS)
38	INTEGER key3(lShare4,MAX_NO_THREADS)
39	INTEGER door1
40	INTEGER door2
41	INTEGER door3
42	INTEGER VALID
43	PARAMETER ( VALID = 1 )
44	INTEGER INVALID
45	PARAMETER ( INVALID = 0 )
46	INTEGER OPEN
47	PARAMETER ( OPEN = 1 )
48	INTEGER SHUT
49	PARAMETER ( SHUT = 0 )