perfstat_diskadapter Subroutine

This subroutine is not supported inside a workload partition (WPAR). It is not aware of a WPAR.

Purpose

Retrieves individual disk adapter usage statistics.

Library

Perfstat Library (libperfstat.a)

Syntax

#include <libperfstat.h>


int perfstat_diskadapter (name, userbuff, sizeof_struct, desired_number)
perfstat_id_t *name;
 perfstat_diskadapter_t *userbuff;
size_t sizeof_struct;
int desired_number;

Description

The perfstat_diskadapter subroutine retrieves one or more individual disk adapter usage statistics. The same function can be used to retrieve the number of available sets of adapter statistics.

To get one or more sets of disk adapter usage metrics, set the name parameter to the name of the first disk adapter for which statistics are desired, and set the desired_number parameter. To start from the first disk adapter, set the name parameter to "" or FIRST_DISKADAPTER. The userbuff parameter must point to a memory area big enough to contain the desired number of perfstat_diskadapter_t structures which will be copied by this function. Upon return, the name parameter will be set to either the name of the next disk adapter, or to "" if all structures have been copied.

To retrieve the number of available sets of disk adapter usage metrics, set the name and userbuff parameters to NULL, and the desired_number parameter to 0. The returned value will be the number of available sets.

The perfstat_diskadapter subroutine retrieves information from the ODM database. This information is automatically cached into a dictionary which is assumed to be frozen once loaded. The perfstat_reset subroutine must be called to flush the dictionary whenever the machine configuration has changed.

To improve system performance, the collection of disk input/output statistics is disabled by default in current releases of AIX®.

To enable the collection of this data, use:

chdev -l sys0 -a iostat=true

To display the current setting, use:

lsattr -E -l sys0 -a iostat

Another way to enable the collection of the disk input/output statistics is to use the sys_parm API and the SYSP_V_IOSTRUN flag:

To get the current status of the flag:

struct vario var;
sys_parm(SYSP_GET,SYSP_V_IOSTRUN, &var);

To set the flag:

struct vario var;
var.v.v_iostrun.value=1; /* 1 to set & 0 to unset */
sys_parm(SYSP_SET,SYSP_V_IOSTRUN, &var);

Parameters

Item	Description
name	Contains either "", FIRST_DISKADAPTER, or a name identifying the first disk adapter for which statistics are desired. For example: `scsi0, scsi1, ...`
userbuff	Points to the memory area to be filled with one or more perfstat_diskadapter_t structures.
sizeof_struct	Specifies the size of the perfstat_diskadapter_t structure: `sizeof(perfstat_diskadapter_t)`
desired_number	Specifies the number of perfstat_diskadapter_t structures to copy to userbuff.

Return Values

Unless the function is used to retrieve the number of available structures, the number of structures filled is returned upon successful completion. If unsuccessful, a value of -1 is returned and the errno global variable is set.

Error Codes

The perfstat_diskadapter subroutine is unsuccessful if one of the following is true:

Item	Description
EINVAL	One of the parameters is not valid.
EFAULT	Insufficient memory.
ENOMEM	The string default length is too short.
ENOMSG	Cannot access the dictionary.

Files

The libperfstat.h file defines standard macros, data types, and subroutines.