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man pages section 9: DDI and DKI Properties and Data Structures

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Updated: Friday, August 13, 2021

kstat2_io (9S)


kstat2_io - structure for v2 I/O kstats


#include <sys/types.h>
#include <sys/kstat2.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

Interface Level

Solaris DDI specific (Solaris DDI)


I/O kstat statistics are kept in a kstat2_io structure. When kstat2_create(9F) function creates an I/O kstat, the ks2_data field is a pointer to one of these structures. The macro KSTAT2_IO_PTR() is provided to retrieve this field. It looks like this:

# define KSTAT2_IO_PTR(kptr) ((kstat2_io_t *)(kptr)->ks2_data)

kstat2_io_t is a data-structure which contains only kstat2_named_t fields. This behaves exactly like an array of kstat2_named_t entries, but with the advantage of being able to access the fields by name rather than having to remember array indices.

Structure Members

The following fields are updated by the driver:

kstat2_named_t nread;      /* number of bytes read */
kstat2_named_t nwritten;   /* number of bytes written *]/
kstat2_named_t reads;      /* number of read operations */
kstat2_named_t writes;     /* number of write operations */

Their values should be accessed through the following macros:


where kiop is obtained using:

kiop = KSTAT2_IO_PTR(kstatp);

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

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

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

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

The following fields are normally not updated by the driver directly as they are managed by the kstat2 queue functions. See kstat2_runq_enter(9F).

kstat2_named_t wtime;	  /* cumulative wait
                                     (pre-service) time */
kstat2_named_t wlentime;     /* cumulative wait
                                length*time product */
kstat2_named_t wlastupdate;  /* last time wait queue
                                changed */
kstat2_named_t rtime;	  /* cumulative run
                                     (service) time */
kstat2_named_t rlentime;     /* cumulative run
                                length*time product */
kstat2_named_t rlastupdate;  /* last time run queue
                                     changed */
kstat2_named_t wcnt;         /* count of elements in
                                wait state */
kstat2_named_t rcnt;         /* count of elements in
                                run state */

The values of these fields are accessed using the following macros:



Example 1 Creating an I/O kstat
        * Initialize the kstat's name path segments.
        * This will result in a URI path for the kstat of:
        *        /disk/mydrv/N/io
        * - where N is the disk instance number.
       const char *pseg[] = { "disk", "mydrv", ddi_inst_str, "io" };

        * Lookup the IO kstat template.
       const kstat2_template_t *tmpl = kstat2_lookup_template(KSTAT2_MT_IO);

        * Now create a persistent IO kstat using the template.
       kstat2_t *ksp = kstat2_create_with_template(pseg,
           sizeof (pseg) / sizeof (char *),
           GLOBAL_ZONEID, io_tmpl,
          "mydrv disk io", KSTAT2_MF_NONE);

       if (ksp != NULL) {
               ksp->ks2_lock = mydrv->iomutex;
               mydrv->kstat = ksp;

See Also

kstat2_create(9F), kstat2(9S), kstat2_create_with_template(9F), kstat2_lookup_template(9F), kstat2_runq_back_to_waitq(9F), kstat2_runq_enter(9F), kstat2_runq_exit(9F), kstat2_waitq_enter(9F), kstat2_waitq_exit(9F), kstat2_waitq_to_runq(9F), kstat2_named(9S)