perfstat_diskpath Interface

Selected fields from the perfstat_diskpath_t structure include: Several other disk path-related metrics (such as the number of blocks read from and written through the path) are also returned. For a complete list, see the perfstat_diskpath_t section in the libperfstat.h header file.

The following code shows an example of how the perfstat_diskpath interface is used:

#include <stdio.h>
#include <stdlib.h>
#include <libperfstat.h>

int main(int argc, char* argv[]) {
   int ret, tot, i;
   perfstat_diskpath_t *statp;
   perfstat_id_t first;
   char *substring;
   perfstat_disk_t dstat;

   /* check how many perfstat_diskpath_t structures are available */
   tot = perfstat_diskpath(NULL, NULL, sizeof(perfstat_diskpath_t), 0);

   /* check for error */
   if (tot < 0)
   {

	perror("perfstat_diskpath");
	exit(-1);
   }

   if (tot == 0)
   {

	printf("No Paths found in the system\n");
	exit(-1);

   }

   /* allocate enough memory for all the structures */
   statp = calloc(tot, sizeof(perfstat_diskpath_t));
   if(statp==NULL){
	printf("No sufficient memory\n");
	exit(-1);
   }
   
   /* set name to first interface */
   strcpy(first.name, FIRST_DISKPATH);
   
   /* ask to get all the structures available in one call */
   /* return code is number of structures returned */
   ret = perfstat_diskpath(&first, statp, sizeof(perfstat_diskpath_t), tot);
   				 
   /* check for error */
   if (ret <= 0)
   {

	perror("perfstat_diskpath");
	exit(-1);
   }

   /* print statistics for each of the disk paths */
   for (i = 0; i < ret; i++) {
       printf("\nStatistics for disk path : %s\n", statp[i].name);
       printf("----------------------\n");
       printf("number of blocks read     : %llu\n", statp[i].rblks);
       printf("number of blocks written  : %llu\n", statp[i].wblks);
       printf("adapter name              : %s\n", statp[i].adapter);
       }
      
          /* retrieve paths for last disk if any */
   if (ret > 0) {
       /* extract the disk name from the last disk path name */
       substring = strstr(statp[ret-1].name, "_Path");
       if (substring == NULL) {
          return (-1);
       }
       substring[0] = '\0';
      
      /* set name to the disk name */
      strcpy(first.name, substring);
      /* retrieve info about disk */ 
      ret = perfstat_disk(&first, &dstat, sizeof(perfstat_disk_t),1);
   
      if (ret <= 0)
      {
          perror("perfstat_diskpath");
          exit(-1);
      }
   
      printf("\nPaths for disk path : %s (%d)\n", dstat.name, dstat.paths_count);
      printf("----------------------\n");


      /* retrieve all paths for this disk */
      ret = perfstat_diskpath(&first, statp, sizeof(perfstat_diskpath_t), dstat.paths_count);
      if (ret <= 0)
      {
          perror("perfstat_diskpath");
          exit(-1);
      }
				 
      /* print statistics for each of the paths */
      for (i = 0; i < ret; i++) {
          printf("\nStatistics for disk path : %s\n", statp[i].name);
          printf("----------------------\n");
          printf("number of blocks read     : %llu\n", statp[i].rblks);
          printf("number of blocks written  : %llu\n", statp[i].wblks);
          printf("adapter name              : %s\n", statp[i].adapter);
          }
     }
}

Statistics for disk path : hdisk0_Path0
----------------------
number of blocks read     : 335354
number of blocks written  : 291416
adapter name              : vscsi0

Paths for disk path : hdisk0 (1)
----------------------

Statistics for disk path : hdisk0_Path0
----------------------
number of blocks read     : 335354
number of blocks written  : 291416
adapter name              : vscsi0