LAPI_Rmw64 子例程

#include <lapi.h>
 
int LAPI_Rmw64(hndl, op, tgt, tgt_var, in_val, prev_tgt_val, org_cntr)
 
lapi_handle_t hndl;
Rmw_ops_t op;
uint tgt;
long long *tgt_var;
long long *in_val;
long long *prev_tgt_val;
lapi_cntr_t *org_cntr;

include 'lapif.h'
 
LAPI_RMW64(hndl, op, tgt, tgt_var, in_val, prev_tgt_val, org_cntr,  ierror)

INTEGER hndl
INTEGER op
INTEGER tgt
INTEGER (KIND=LAPI_ADDR_TYPE) :: tgt_var
INTEGER (KIND=LAPI_LONG_LONG_TYPE) :: in_val, prev_tgt_val
TYPE (LAPI_CNTR_T) :: org_cntr
INTEGER ierror

这些操作 (操作) 在 恩德尔引用的上下文中执行。 执行这些调用的结果就好像以原子方式执行了以下代码:

*prev_tgt_val = *tgt_var;
*tgt_var      = f(*tgt_var, *in_val);

对于 COMPARE_AND_SWAP， in_val 被视为指向两个整数的数组的指针， op 是以下原子操作:

if(*tgt_var == in_val[0])  {
   *prev_tgt_val = TRUE;
   *tgt_var      = in_val[1];
} else {
   *prev_tgt_val = FALSE;
}

1. 要在两个任务 (使用 FETCH_AND_ADD) 之间同步数据值，请执行以下操作:

   {
   
         long long local_var;
         long long *addr_list;
   
         /* both tasks initialize local_var to a value        */
   
         /* local_var addresses are exchanged and stored      */
         /* in addr_list (using LAPI_Address_init64)          */
         /* addr_list[tgt] now contains address of            */
         /* local_var on tgt                                  */
         .
         .
         .
         /* add value to local_var on some task               */
   
         /* use LAPI to add value to local_var on remote task */
         LAPI_Rmw64(hndl, FETCH_AND_ADD, tgt, addr_list[tgt],
                    value, prev_tgt_val, &org_cntr);
   
         /* local_var on remote task has been increased       */
         /* by value.  prev_tgt_val now contains value of     */
         /* local_var on remote task before the addition      */
   
   }
   

2. 要在两个任务 (使用 SWAP) 之间同步数据值，请执行以下操作:

   
   {
   
         long long local_var;
         long long *addr_list;
   
         /* local_var addresses are exchanged and stored           */
         /* in addr_list (using LAPI_Address_init64).              */
         /* addr_list[tgt] now contains the address of             */
         /* local_var on tgt.                                      */
         .
         .
         .
         /* local_var is assigned some value                       */
   
         /* assign local_var to local_var on the remote task       */
         LAPI_Rmw64(hndl, SWAP, tgt, addr_list[tgt],
                    local_var, prev_tgt_val, &org_cntr);
   
         /* local_var on the remote task is now equal to local_var */
         /* on the local task. prev_tgt_val now contains the value */
         /* of local_var on the remote task before the swap.       */
   
   }
   

3. 要有条件地交换数据值 (与 COMPARE_AND_SWAP):

   
   {
   
         long long local_var;
         long long *addr_list;
         long long in_val[2];
   
         /* local_var addresses are exchanged and stored        */
         /* in addr_list (using LAPI_Address_init64).           */
         /* addr_list[tgt] now contains the address of          */
         /* local_var on tgt.                                   */
         .
         .
         .
         /* if local_var on remote_task is equal to comparator, */
         /* assign value to local_var on the remote task        */
   			
         in_val[0] = comparator;
         in_val[1] = value;
   
         LAPI_Rmw64(hndl, COMPARE_AND_SWAP, tgt, addr_list[tgt],
                    in_val, prev_tgt_val, &org_cntr);
   
         /* local_var on remote task is now in_val[1] if it     */
         /* had previously been equal to in_val[0]. If the      */ 
         /* swap was performed, prev_tgt_val now contains       */ 
         /* TRUE; otherwise, it contains FALSE.                 */
   
   }