NAME

kstat_io - structure for I/O kstats

SYNOPSIS

#include <sys/types.h>
#include <sys/kstat.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

INTERFACE LEVEL

illumos DDI specific (illumos DDI)

DESCRIPTION

I/O kstat statistics are kept in a kstat_io structure. When kstat_create(9F) creates an I/O kstat, the ks_data field is a pointer to one of these structures. The macro KSTAT_IO_PTR() is provided to retrieve this field. It looks like this:

#define KSTAT_IO_PTR(kptr)	((kstat_io_t *)(kptr)->ks_data)

STRUCTURE MEMBERS

u_longlong_t      nread;      /* number of bytes read */
u_longlong_t      nwritten;   /* number of bytes written *]/
ulong_t           reads;      /* number of read operations */
ulong_t           writes;     /* number of write operations */

The nread field should be updated by the driver with the number of bytes successfully read upon completion.

The nwritten field should be updated by the driver with the number of bytes successfully written upon completion.

The reads field should be updated by the driver after each successful read operation.

The writes field should be updated by the driver after each successful write operation.

Other I/O statistics are updated through the use of the kstat_queue(9F) functions.

SEE ALSO

kstat_create(9F), kstat_named_init(9F), kstat_queue(9F), kstat_runq_back_to_waitq(9F), kstat_runq_enter(9F), kstat_runq_exit(9F), kstat_waitq_enter(9F), kstat_waitq_exit(9F), kstat_waitq_to_runq(9F)

Writing Device Drivers