C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/eesupp/inc/BAR2.h,v 1.1 1998/09/29 18:54:25 cnh Exp $
C
C     /==========================================================\
C     | BAR2.h                                                   |
C     | o Globals used by BAR2 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 BAR2_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 BAR2( myThid )                                  |
C     |     where myThid is myThreadId                           |
C     |     on CRAY, NEC FBAR will just do C$DIR BARRIER         |
C     |     or CALL BARRIER or the like.                         |
C     |     on T3E FBAR does CALL BARRIER(...) or something      |
C     |     need to check this.                                  |
C     \==========================================================/
      COMMON /BAR2_BUFFER_I/
     &  BAR2_level,
     &  BAR2_barrierCount, 
     &  BAR2_spinsCount, BAR2_spinsMax, BAR2_spinsMin
      INTEGER BAR2_level(cacheLineSize/4,MAX_NO_THREADS)
      INTEGER BAR2_barrierCount(cacheLineSize/4,MAX_NO_THREADS)
      INTEGER BAR2_spinsCount(cacheLineSize/4,MAX_NO_THREADS)
      INTEGER BAR2_spinsMax(cacheLineSize/4,MAX_NO_THREADS)
      INTEGER BAR2_spinsMin(cacheLineSize/4,MAX_NO_THREADS)

      COMMON /BAR2_L/ bar2CollectStatistics
      LOGICAL bar2CollectStatistics