t9ping.c - plan9port - [fork] Plan 9 from user space
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       ---
       t9ping.c (1559B)
       ---
            1 #include <u.h>
            2 #include <libc.h>
            3 
            4 typedef uvlong u64int;
            5 
            6 #define TWID64        ((u64int)~(u64int)0)
            7 
            8 
            9 u64int
           10 unittoull(char *s)
           11 {
           12         char *es;
           13         u64int n;
           14 
           15         if(s == nil)
           16                 return TWID64;
           17         n = strtoul(s, &es, 0);
           18         if(*es == 'k' || *es == 'K'){
           19                 n *= 1024;
           20                 es++;
           21         }else if(*es == 'm' || *es == 'M'){
           22                 n *= 1024*1024;
           23                 es++;
           24         }else if(*es == 'g' || *es == 'G'){
           25                 n *= 1024*1024*1024;
           26                 es++;
           27         }
           28         if(*es != '\0')
           29                 return TWID64;
           30         return n;
           31 }
           32 
           33 void
           34 main(int argc, char *argv[])
           35 {
           36         int fd, i;
           37         int n = 1000, m;
           38         int s = 1;
           39         double *t, t0, t1;
           40         uchar *buf;
           41         double a, d, max, min;
           42 
           43         m = OREAD;
           44         ARGBEGIN{
           45         case 'n':
           46                 n = atoi(ARGF());
           47                 break;
           48         case 's':
           49                 s = unittoull(ARGF());
           50                 if(s < 1 || s > 1024*1024)
           51                         sysfatal("bad size");
           52                 break;
           53         case 'r':
           54                 m = OREAD;
           55                 break;
           56         case 'w':
           57                 m = OWRITE;
           58                 break;
           59         }ARGEND
           60 
           61         fd = 0;
           62         if(argc == 1){
           63                 fd = open(argv[0], m);
           64                 if(fd < 0)
           65                         sysfatal("could not open file: %s: %r", argv[0]);
           66         }
           67 
           68         buf = malloc(s);
           69         t = malloc(n*sizeof(double));
           70 
           71         t0 = nsec();
           72         for(i=0; i<n; i++){
           73                 if(m == OREAD){
           74                         if(pread(fd, buf, s, 0) < s)
           75                                 sysfatal("bad read: %r");
           76                 }else{
           77                         if(pwrite(fd, buf, s, 0) < s)
           78                                 sysfatal("bad write: %r");
           79                 }
           80                 t1 = nsec();
           81                 t[i] = (t1 - t0)*1e-3;
           82                 t0 = t1;
           83         }
           84 
           85         a = 0.;
           86         d = 0.;
           87         max = 0.;
           88         min = 1e12;
           89 
           90         for(i=0; i<n; i++){
           91                 a += t[i];
           92                 if(max < t[i])
           93                         max = t[i];
           94                 if(min > t[i])
           95                         min = t[i];
           96         }
           97 
           98         a /= n;
           99 
          100         for(i=0; i<n; i++)
          101                 d += (a - t[i]) * (a - t[i]);
          102         d /= n;
          103         d = sqrt(d);
          104 
          105         print("avg = %.0fµs min = %.0fµs max = %.0fµs dev = %.0fµs\n", a, min, max, d);
          106 
          107         exits(0);
          108 }