vmstat - Allow sub-second intervals to be specified.

* Allows e.g. vmstat 0.1 or even vmstat 1.5.

* Note that fields which are printed in per-second format are still
  printed in per-second format.  Sub-second rates may cause reduced
  reliability for these fields.

diff --git a/usr.bin/vmstat/vmstat.c b/usr.bin/vmstat/vmstat.c
index d92e6a9..d63526a 100644 (file)
--- a/usr.bin/vmstat/vmstat.c
+++ b/usr.bin/vmstat/vmstat.c
@@ -150,7 +150,7 @@ int
 main(int argc, char **argv)
 {
        int c, todo;
-       u_int interval;
+       u_int interval;         /* milliseconds */
        int reps;
        char *memf, *nlistf;
        char errbuf[_POSIX2_LINE_MAX];
@@ -207,7 +207,7 @@ main(int argc, char **argv)
                        ++verbose;
                        break;
                case 'w':
-                       interval = atoi(optarg);
+                       interval = (u_int)(strtod(optarg, NULL) * 1000.0);
                        break;
                case 'z':
                        todo |= ZMEMSTAT;
@@ -269,7 +269,7 @@ main(int argc, char **argv)
 #define        BACKWARD_COMPATIBILITY
 #ifdef BACKWARD_COMPATIBILITY
        if (*argv) {
-               interval = atoi(*argv);
+               interval = (u_int)(strtod(*argv, NULL) * 1000.0);
                if (*++argv)
                        reps = atoi(*argv);
        }
@@ -278,8 +278,9 @@ main(int argc, char **argv)
        if (interval) {
                if (!reps)
                        reps = -1;
-       } else if (reps)
-               interval = 1;
+       } else if (reps) {
+               interval = 1000;
+       }
 
 #ifdef notyet
        if (todo & FORKSTAT)
@@ -388,14 +389,12 @@ static void
 dovmstat(u_int interval, int reps)
 {
        struct vmtotal total;
-       time_t uptime, halfuptime;
        struct devinfo *tmp_dinfo;
        size_t vmm_size = sizeof(vmm);
        size_t vms_size = sizeof(vms);
        size_t vmt_size = sizeof(total);
+       int initial = 1;
 
-       uptime = getuptime();
-       halfuptime = uptime / 2;
        signal(SIGCONT, needhdr);
 
        for (hdrcnt = 1;;) {
@@ -463,7 +462,7 @@ dovmstat(u_int interval, int reps)
                printf("%2d %1d %1d",
                    total.t_rq - 1, total.t_dw + total.t_pw, total.t_sw);
 #define vmstat_pgtok(a) ((a) * vms.v_page_size >> 10)
-#define        rate(x) (((x) + halfuptime) / uptime)   /* round */
+#define rate(x)        (initial ? (x) : ((x) * 1000 + interval / 2) / interval)
                printf(" %7ld %6ld ",
                    (long)vmstat_pgtok(total.t_avm), (long)vmstat_pgtok(total.t_free));
                printf("%4lu ",
@@ -491,16 +490,8 @@ dovmstat(u_int interval, int reps)
                if (reps >= 0 && --reps <= 0)
                        break;
                ovmm = vmm;
-               uptime = interval;
-               /*
-                * We round upward to avoid losing low-frequency events
-                * (i.e., >= 1 per interval but < 1 per second).
-                */
-               if (interval != 1)
-                       halfuptime = (uptime + 1) / 2;
-               else
-                       halfuptime = 0;
-               sleep(interval);
+               usleep(interval * 1000);
+               initial = 0;
        }
 }