perfstat_disk Interface

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

The following program emulates diskstat behavior and also shows an example of how the perfstat_disk interface is used:

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

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

    /* check how many perfstat_disk_t structures are available */
    tot =  perfstat_disk(NULL, NULL, sizeof(perfstat_disk_t), 0);
    
    /* check for error */
    if (tot < 0)
    {
	perror("perfstat_disk");
	exit(-1);
    }
    if (tot == 0)
    {
        printf("No disks found in the system\n");
        exit(-1);
    }

    /* allocate enough memory for all the structures */
    statp = calloc(tot, sizeof(perfstat_disk_t));
    
    /* set name to first interface */
    strcpy(first.name, FIRST_DISK);
    
    /* ask to get all the structures available in one call */
    /* return code is number of structures returned */
    ret = perfstat_disk(&first, statp,
                        sizeof(perfstat_disk_t), tot);

/* check for error */
    if (ret <= 0)
    {
	perror("perfstat_disk");
	exit(-1);
    }

    /* print statistics for each of the disks */
    for (i = 0; i < ret; i++) {
        printf("\nStatistics for disk : %s\n", statp[i].name);
        printf("-------------------\n");
        printf("description              : %s\n", statp[i].description);
        printf("volume group name        : %s\n", statp[i].vgname);
        printf("adapter name             : %s\n", statp[i].adapter);
        printf("size                     : %llu MB\n", statp[i].size);
        printf("free space               : %llu MB\n", statp[i].free);
        printf("number of blocks read    : %llu blocks of %llu bytes\n", statp[i].rblks, statp[i].bsize);
        printf("number of blocks written : %llu blocks of %llu bytes\n", statp[i].wblks, statp[i].bsize);
        }
     }

The preceding program produces the following output:

Statistics for disk : hdisk1
-------------------
description              : 16 Bit SCSI Disk Drive
volume group name        : rootvg
adapter name             : scsi0
size                     : 4296 MB
free space               : 2912 MB
number of blocks read    : 403946 blocks of 512 bytes
number of blocks written : 768176 blocks of 512 bytes

Statistics for disk : hdisk0
-------------------
description              : 16 Bit SCSI Disk Drive
volume group name        : None
adapter name             : scsi0
size                     : 0 MB
free space               : 0 MB
number of blocks read    : 0 blocks of 512 bytes
number of blocks written : 0 blocks of 512 bytes

Statistics for disk : cd0
-------------------
description              : SCSI Multimedia CD-ROM Drive
volume group name        : not available
adapter name             : scsi0
size                     : 0 MB
free space               : 0 MB
number of blocks read    : 3128 blocks of 2048 bytes
number of blocks written : 0 blocks of 2048 bytes