2 files changed, 28 insertions, 24 deletions

diff --git a/usr.bin/top/top.1 b/usr.bin/top/top.1
index a26fbc181229..5b422fffe737 100644
--- a/usr.bin/top/top.1
+++ b/usr.bin/top/top.1
@@ -147,7 +147,7 @@ no information is available about the percentage of time spent by the CPU in eve
 .It Fl s Ar time
 Set the delay between screen updates to
 .Ar time
-seconds.
+seconds, which may be fractional.
 The default delay between updates is 1 second.
 .It Fl o Ar field
 Sort the process display area on the specified field.
diff --git a/usr.bin/top/top.c b/usr.bin/top/top.c
index 01cad421b64c..cd357a092e9f 100644
--- a/usr.bin/top/top.c
+++ b/usr.bin/top/top.c
@@ -233,7 +233,7 @@ main(int argc, const char *argv[])
     static char tempbuf2[50];
 	sigset_t old_sigmask, new_sigmask;
     int topn = Infinity;
-    double delay = 2;
+    struct timeval delay = { 2, 0 };
     int displays = 0;		/* indicates unspecified */
     int sel_ret = 0;
     time_t curr_time;
@@ -377,20 +377,26 @@ main(int argc, const char *argv[])
 		break;
 	      }
 
-		  case 's':
-			delay = strtod(optarg, &nptr);
-			if (nptr == optarg) {
-				warnx("warning: invalid delay");
-				delay = 2;
-				warnings++;
-			}
-			if (delay < 0) {
-				warnx("warning: seconds delay should be positive -- using default");
-				delay = 2;
-				warnings++;
-			}
-
-		break;
+	      case 's':
+	      {
+		  double delay_d = strtod(optarg, &nptr);
+		  if (nptr == optarg)
+		  {
+		      warnx("warning: invalid delay");
+		      warnings++;
+		  }
+		  else if (delay_d <= 0)
+		  {
+		      warnx("warning: seconds delay should be positive -- using default");
+		      warnings++;
+		  }
+		  else
+		  {
+		      delay.tv_sec = delay_d;
+		      delay.tv_usec = (delay_d - delay.tv_sec) * 1e6;
+		  }
+		  break;
+	      }
 
 	      case 'q':		/* be quick about it */
 			errno = 0;
@@ -704,7 +710,8 @@ restart:
 	    no_command = true;
 	    if (!interactive)
 	    {
-		usleep(delay * 1e6);
+		timeout = delay;
+		select(0, NULL, NULL, NULL, &timeout);
 		if (leaveflag) {
 		    end_screen();
 		    exit(0);
@@ -718,8 +725,7 @@ restart:
 		/* set up arguments for select with timeout */
 		FD_ZERO(&readfds);
 		FD_SET(0, &readfds);		/* for standard input */
-		timeout.tv_sec  = delay;
-		timeout.tv_usec = 0;
+		timeout = delay;
 
 		if (leaveflag) {
 		    end_screen();
@@ -880,12 +886,10 @@ restart:
 
 			    case CMD_delay:	/* new seconds delay */
 				new_message(MT_standout, "Seconds to delay: ");
-				if ((i = readline(tempbuf1, 8, true)) > -1)
+				if ((i = readline(tempbuf1, 8, true)) > 0)
 				{
-				    if ((delay = i) == 0)
-				    {
-					delay = 1;
-				    }
+				    delay.tv_sec = i;
+				    delay.tv_usec = 0;
 				}
 				clear_message();
 				break;