te
Copyright (c) 2000, Sun Microsystems, Inc.
The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
kstat_io - structure for I/O kstats

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

illumos DDI specific (illumos DDI) 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)

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.

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