Administration Guide

Get (C)

This C program is an example of the use of LAPI_Get:

/* Get.c
** Example Program illustrating the use of LAPI_Get
*/
 
#include <lapi.h>
 
#define A_MAX     2
#define I_MAX     10
 
int
main(int argc, char **argv)                                               main
{
   lapi_handle_t t_hndl;               /* LAPI context handle - */
                                       /* returned */
   lapi_info_t   t_info;               /* LAPI info structure */
   int  task_id,                       /* My task id */
                 num_tasks;            /* Number of tasks in my job */
   int           t_buf[I_MAX];         /* Buffer to manipulate */
   lapi_cntr_t   l_cntr;               /* Origin counter */
   lapi_cntr_t   t_cntr;               /* Target counter */
   void          *global_addr[A_MAX];  /* Array to store t_buf addr */
                                       /* from all the tasks.  The */
                                       /* size of this array needs */
                                       /* to each number of tasks */
   void          *tgt_addr[A_MAX];     /* Array to store target */
                                       /* counter addr from all the */
                                       /* tasks. */
   int           loop, rc, tgt, val, cur_val;
   char          err_msg_buf[LAPI_MAX_ERR_STRING];
 
   bzero(&t_info, sizeof(lapi_info_t));
   t_info.err_hndlr = NULL;   /* Not registering error handler /*
                              /* function */
   if ((rc = LAPI_Init(&t_hndl, &t_info)) != LAPI_SUCCESS) }
       LAPI_Msg_string(rc, err_msg_buf);
       printf("Error Message: %s, rc = %d\n", err_msg_buf, rc);
       exit (rc);
   }
   rc = LAPI_Qenv(t_hndl, TASK_ID, &task_id);     /* Get task id */
                                                  /* within job */
   rc = LAPI_Qenv(t_hndl, NUM_TASKS, &num_tasks); /* Get no. of tasks */
                                                  /* in job */
 
   if (num_tasks != 2) }
       printf("Error Message: run with MP_PROCS set to 2\n");
       exit(1);
   }
 
   /* Turn off parameter checking - default is on */
   rc = LAPI_Senv(t_hndl, ERROR_CHK, 0);
 
   /* Initialize counters to be zero at the start */
   rc = LAPI_Setcntr(t_hndl, &l_cntr, 0);
   rc = LAPI_Setcntr(t_hndl, &t_cntr, 0);
 
   /* Exchange buffer address and target_counter address of every task */
   rc = LAPI_Address_init(t_hndl,t_buf,global_addr);  /* Collective */
                                                      /* call */
                                                                           ...main
   rc = LAPI_Address_init(t_hndl,&t_cntr,tgt_addr);   /* Collective */
                                                      /* call */
 
   if (task_id == 0) { /* Task id is 0 , Origin */
       tgt = task_id + 1;
       for (loop=0; loop < I_MAX; loop++) { /* Zero out buffer */
           t_buf[loop] = 0;
       }
       rc = LAPI_Gfence(t_hndl);  /* Global fence to sync before */
                                  /* starting */
       rc = LAPI_Get(t_hndl, tgt, I_MAX*sizeof(int), global_addr[tgt],
                               (void *)t_buf, tgt_addr [tgt], &l_cntr);
       rc = LAPI_Waitcntr(t_hndl, &l_cntr, 1, NULL);
 
       printf("Node %d, done issuing Get from node %d\n", task_id, tgt) ;
       printf("Result of Get from node %d:\n", tgt);
       for (loop=0; loop < I_MAX; loop++) { /* Update buffer */
           printf("Val[%d] = %d\n", loop, t_buf[loop]);
       }
   } else { /* Task id is 1 , Target */
       tgt = task_id - 1;
       for (loop=0; loop < I_MAX; loop++) { /* Update buffer */
           t_buf[loop] = loop + task_id;
       }
       rc = LAPI_Gfence(t_hndl);  /* Global fence to sync before */
                                  /* starting */
       rc = LAPI_Getcntr(t_hndl, &t_cntr, &val);
       while (val != 1) {
           sleep(1); /* Do some work */
           rc = LAPI_Probe(t_hndl); /* Poll the adapter once */
           rc = LAPI_Getcntr(t_hndl, &t_cntr, &val);
       }
       /* To clear the t_cntr value */
       rc = LAPI_Waitcntr(t_hndl, &t_cntr, val, &cur_val);
       printf("Node %d, done doing work and processing Get\n", task_id) ;
    }
    rc = LAPI_Gfence(t_hndl); /* Global fence to sync before */
                              /* terminating job */
    rc = LAPI_Term(t_hndl);
}