BSD 4_3_Tahoe release

[unix-history] / usr / src / new / dsh / src / getloadave.c

/*(@(#)getloadave.c     1.2             /ra/csr/presotto/hacks/src/worm/sccs/s.getloadave.c)*/
#include <sys/types.h>
#include <nlist.h>
#include <sys/stat.h>

#define MAXRETRIES 20

struct  nlist nl[] = {
#define NL_AVENRUN      0
       { "_avenrun" },
       0
};
int     kmemf = -1;             /* fd for kmem */
time_t  vmunixdate = 0;         /* update time for vmunix */

initnlist ()
{
   int                 i;
   struct nlist        *nlp;
   struct stat         sbuf;

   i = stat ("/vmunix", &sbuf);
   if (i == -1) {
       error ("can't read /vmunix");
   }
   if (vmunixdate != sbuf.st_mtime) {
       for (i = 0; i < MAXRETRIES; sleep (5), i++) {
           for (nlp = &nl[sizeof (nl) / sizeof (nl[0])]; --nlp >= nl; ) {
               nlp->n_value = 0;
               nlp->n_type = 0;
           }
           nlist("/vmunix", nl);
           if (nl[0].n_value == 0) {
               warn ("/vmunix namelist botch");
               continue;
           }
           break;
       }
       if (i >= MAXRETRIES)
           exit (-1);
       vmunixdate = sbuf.st_mtime;
   }

   if (kmemf == -1) {
       kmemf = open("/dev/kmem", 0);
       if (kmemf < 0) {
           error ("opening /dev/kmem");
       }
   }
}


/*
*      Get the current load average 
*/
getloadave (avenrun)
double  *avenrun;
{
   double              template[3];

   initnlist ();
   (void) lseek(kmemf, (long)nl[NL_AVENRUN].n_value, 0);
   (void) read(kmemf, (char *)avenrun, sizeof (template));
}