static void print_vminfo(kstat_t *kp)   
{   
      vminfo_t *vminfop;   
      vminfop = (vminfo_t *)(kp->ks_data);   
    
      printf("Free memory: %dn", vminfop->freemem);   
      printf("Swap reserved: %dn" , vminfop->swap_resv);   
      printf("Swap allocated: %dn" , vminfop->swap_alloc);   
      printf("Swap available: %dn", vminfop->swap_avail);   
      printf("Swap free: %dn", vminfop->swap_free);   
} 
 

typedef struct kstat_named {   
     char name[KSTAT_STRLEN];         /* name of counter */   
     uchar_t data_type;               /* data type */   
     union {   
         char c[16];             /* enough for 128-bit ints */   
         int32_t i32;   
         uint32_t ui32;   
         int64_t i64;   
         uint64_t ui64;   
         /* These structure members are obsolete */   
         int32_t l;   
         uint32_t ul;   
         int64_t ll;   
         uint64_t ull;   
     } value;                  /* value of counter */   
 } kstat_named_t;   
   #define KSTAT_DATA_CHAR       0   
   #define KSTAT_DATA_INT32      1   
   #define KSTAT_DATA_UINT32     2   
   #define KSTAT_DATA_INT64      3   
   #define KSTAT_DATA_UINT64     4   
   /* These types are obsolete */   
   #define KSTAT_DATA_LONG       1   
   #define KSTAT_DATA_ULONG      2   
   #define KSTAT_DATA_LONGLONG   3   
   #define KSTAT_DATA_ULONGLONG  4   
   #define KSTAT_DATA_FLOAT      5   
   #define KSTAT_DATA_DOUBLE     6  
 

 Example 6 - Timer kstat Definitions from /usr/include/kstat.h 
 typedef struct kstat_timer {   
     char name[KSTAT_STRLEN];         /* event name */   
     uchar_t resv;                    /* reserved */   
     u_longlong_t num_events;         /* number of events */       
     hrtime_t elapsed_time;           /* cumulative elapsed time */   
     hrtime_t min_time;               /* shortest event duration */   
     hrtime_t max_time;               /* longest event duration */   
     hrtime_t start_time;             /* previous event start time */   
     hrtime_t stop_time;              /* previous event stop time */   
 } kstat_timer_t; 
  

Example 7 - Interrupt kstat Definitions from /usr/include/kstat.h 
#define KSTAT_INTR_HARD      0    
#define KSTAT_INTR_SOFT      1    
#define KSTAT_INTR_WATCHDOG  2    
#define KSTAT_INTR_SPURIOUS  3    
#define KSTAT_INTR_MULTSVC   4    
#define KSTAT_NUM_INTRS      5    
typedef struct kstat_intr {            
    uint_t intrs[KSTAT_NUM_INTRS]; /* interrupt counters */    
} kstat_intr_t; 
 

typedef struct kstat_io {   
/*   
  * Basic counters.   
  */   
  u_longlong_t nread;    /* number of bytes read */   
  u_longlong_t nwritten; /* number of bytes written */   
  uint_t       reads;    /* number of read operations */   
  uint_t       writes;   /* number of write operations */   
  hrtime_t wtime;           /* cumulative wait (pre-service) time */   
  hrtime_t wlentime;        /* cumulative wait length*time product*/   
  hrtime_t wlastupdate;     /* last time wait queue changed */   
  hrtime_t rtime;           /* cumulative run (service) time */   
  hrtime_t rlentime;        /* cumulative run length*time product */   
  hrtime_t rlastupdate;     /* last time run queue changed */   
  uint_t wcnt;              /* count of elements in wait state */   
  uint_t rcnt;              /* count of elements in run state */   
} kstat_io_t; 
 

Stated programmatically:  
  
if (queue length != 0) {   
    time += elapsed time since last state change;   
    lentime +=  (elapsed time since last state change * queue length);   
} 
 

ks_module 
ks_instance 
ks_name 
 

kstat_ctl_t *kstat_open(void); 
    : 커널 통계 라이브러리 (kernel statistics library)에 대한 접근하는 kstat 제어 구조체를 초기화한다. 
  
리턴값 : libkstat 함수에 kc argument로 들어가는 kstat_ctl_t 구조체에 대한 pointer를 리턴 한다. 
   ex) 
        kstat_ctl_t kc; 
        kc = kstat_open(); 
kstat_t *kstat_lookup(kstat_ctl_t *kc, char *ks_module, int ks_instance, char *ks_name) 
    : 인자로 들어가는 ks_module, ks_instance, ks_name을 알아내기 위해 kstat의 kstat chain을 검색 한다. 
 

    - kc_chain_update()의 리턴 값 
          chain이 update 될 경우 새로운 KCID 생성 
          chain에 변화가 없다면 0 
          어떠한 error가 탐지된다면 -1 
 

 #include <kstat.h> 
 

cc -o print_some_kstats -lkstat print_some_kstats.c 
 

 Example 9 - Sample Program to Print kstats of Different Types  
 /*  print_some_kstats.c:   
 *  print out a couple of interesting things   
 */   
 #include <kstat.h>   
 #include <stdio.h> 
 #include <inttypes.h> 
 #define SLEEPTIME 10   
    
 void my_named_display(char *, char *, kstat_named_t *);   
 void my_io_display(char *, char *, kstat_io_t);   
    
 main(int argc, char **argv)   
 {   
      kstat_ctl_t   *kc;   
      kstat_t       *ksp;   
      kstat_io_t     kio;   
      kstat_named_t *knp;   
    
      kc = kstat_open();   
    
      /*   
       * Print out the CPU speed. We make two assumptions here:   
       * 1) All CPUs are the same speed, so we'll just search for the   
       *    first one;   
       * 2) At least one CPU is online, so our search will always   
       *    find something. :)   
       */   
      ksp = kstat_lookup(kc, "cpu_info", -1, NULL);   
      kstat_read(kc, ksp, NULL);   
      /* lookup the CPU speed data record */   
      knp = kstat_data_lookup(ksp, "clock_MHz");    
      printf("CPU speed of system is ");   
      my_named_display(ksp->ks_name, ksp->ks_class, knp);   
      printf("n");   
    
      /* dump some info about all I/O kstats every   
         SLEEPTIME seconds  */   
      while(1) {   
         /* make sure we have current data */   
          if(kstat_chain_update(kc))   
              fprintf(stderr, "<<State Changed>>n");    
          for (ksp = kc->kc_chain; ksp != NULL; ksp = ksp->ks_next) {   
            if (ksp->ks_type == KSTAT_TYPE_IO) {   
               kstat_read(kc, ksp, &kio);   
               my_io_display(ksp->ks_name, ksp->ks_class, kio);   
            }   
          }   
          sleep(SLEEPTIME);   
      } /* while(1) */   
    
 }   
    
 void my_io_display(char *devname, char *class, kstat_io_t k)   
 {   
      printf("Name: %s Class:    
      printf("tnumber of bytes read    
      printf("tnumber of bytes written    
      printf("tnumber of read operations    
      printf("tnumber of write operations    
 }   
    
 void    
 my_named_display(char *devname, char *class, kstat_named_t *knp)   
 {   
      switch(knp->data_type) {   
      case KSTAT_DATA_CHAR:   
           printf("%.16s",knp->value.c);   
           break;   
      case KSTAT_DATA_INT32:   
           printf("%" PRId32,knp->value.i32);   
           break;   
      case KSTAT_DATA_UINT32:   
           printf("%" PRIu32,knp->value.ui32);   
           break;   
      case KSTAT_DATA_INT64:   
           printf("%" PRId64,knp->value.i64);   
           break;   
      case KSTAT_DATA_UINT64:   
           printf("%" PRIu64,knp->value.ui64);   
     }   
 }