--- MITgcm/eesupp/inc/GLOBAL_MAX.h 2001/04/12 10:52:47 1.1 +++ MITgcm/eesupp/inc/GLOBAL_MAX.h 2001/05/29 14:01:35 1.2 @@ -0,0 +1,33 @@ +C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/eesupp/inc/GLOBAL_MAX.h,v 1.2 2001/05/29 14:01:35 adcroft Exp $ +C $Name: $ +C +C /==========================================================\ +C | GLOBAL_MAX.h | +C | o Globals used by Fortran global max routine. | +C |==========================================================| +C | The global max shared memory scheme uses global heap data| +C | structures (.i.e COMMON blocks ). Each thread writes to | +C | an its own element of the shared memory array and then | +C | one thread reads all the entries and maxs them. The max | +C | result is then read by all threads. | +C | Remember - you are working with regions of memory that | +C | are being updated concurrently by different threads. | +C | What happens, when it happens and who gets to see what | +C | happens at what stage depends on the computer systems | +C | memory model. Every computer has a different memory model| +C | and they are never simple. In all current platforms it is| +C | possible for one thread to see events happening in a | +C | different order from the order they are written in the | +C | code. | +C | Unless you understand this it is not a good idea to | +C | make modifications te way these header files are setup or| +C | the way the global sum routines work. | +C \==========================================================/ + COMMON / GMAX_COMMON_R8 / phiGMRL + Real*8 phiGMRL(lShare8, MAX_NO_THREADS ) + + COMMON / GMAX_COMMON_R4 / phiGMRS + Real*4 phiGMRS(lShare4, MAX_NO_THREADS ) + + COMMON / GMAX_COMMON_I / phiGMI + INTEGER phiGMI (lShare4, MAX_NO_THREADS )