4.3BSD - /usr/src/new/dsh/src/getloadave.c

   1: /*(@(#)getloadave.c	1.2		/ra/csr/presotto/hacks/src/worm/sccs/s.getloadave.c)*/
   2: #include <sys/types.h>
   3: #include <nlist.h>
   4: #include <sys/stat.h>
   5: 
   6: #define MAXRETRIES 20
   7: 
   8: struct  nlist nl[] = {
   9: #define NL_AVENRUN  0
  10:     { "_avenrun" },
  11:     0
  12: };
  13: int kmemf = -1;     /* fd for kmem */
  14: time_t  vmunixdate = 0;     /* update time for vmunix */
  15: 
  16: initnlist ()
  17: {
  18:     int         i;
  19:     struct nlist    *nlp;
  20:     struct stat     sbuf;
  21: 
  22:     i = stat ("/vmunix", &sbuf);
  23:     if (i == -1) {
  24:     error ("can't read /vmunix");
  25:     }
  26:     if (vmunixdate != sbuf.st_mtime) {
  27:     for (i = 0; i < MAXRETRIES; sleep (5), i++) {
  28:         for (nlp = &nl[sizeof (nl) / sizeof (nl[0])]; --nlp >= nl; ) {
  29:         nlp->n_value = 0;
  30:         nlp->n_type = 0;
  31:         }
  32:         nlist("/vmunix", nl);
  33:         if (nl[0].n_value == 0) {
  34:         warn ("/vmunix namelist botch");
  35:         continue;
  36:         }
  37:         break;
  38:     }
  39:     if (i >= MAXRETRIES)
  40:         exit (-1);
  41:     vmunixdate = sbuf.st_mtime;
  42:     }
  43: 
  44:     if (kmemf == -1) {
  45:     kmemf = open("/dev/kmem", 0);
  46:     if (kmemf < 0) {
  47:         error ("opening /dev/kmem");
  48:     }
  49:     }
  50: }
  51: 
  52: 
  53: /*
  54:  *	Get the current load average
  55:  */
  56: getloadave (avenrun)
  57: double  *avenrun;
  58: {
  59:     double      template[3];
  60: 
  61:     initnlist ();
  62:     (void) lseek(kmemf, (long)nl[NL_AVENRUN].n_value, 0);
  63:     (void) read(kmemf, (char *)avenrun, sizeof (template));
  64: }

Defined functions

Defined variables

Defined macros