[src/trunk]: src/usr.bin/vmstat when picking which 2 disks to show in the 'vm...

[mrg <mrg%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1e49fcf573df
branches:  trunk
changeset: 359940:1e49fcf573df
user:      mrg <mrg%NetBSD.org@localhost>
date:      Tue Feb 01 09:18:07 2022 +0000

description:
when picking which 2 disks to show in the 'vmstat' default output
and they haven't been specified on the command line, pick the two
devices that have had the largest read+write IO bytes count.

diffstat:

 usr.bin/vmstat/vmstat.c |  33 ++++++++++++++++++++++++++-------
 1 files changed, 26 insertions(+), 7 deletions(-)

diffs (62 lines):

diff -r 3fef8746abe5 -r 1e49fcf573df usr.bin/vmstat/vmstat.c
--- a/usr.bin/vmstat/vmstat.c   Tue Feb 01 08:58:25 2022 +0000
+++ b/usr.bin/vmstat/vmstat.c   Tue Feb 01 09:18:07 2022 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: vmstat.c,v 1.248 2021/11/27 22:16:42 rillig Exp $ */
+/* $NetBSD: vmstat.c,v 1.249 2022/02/01 09:18:07 mrg Exp $ */
 
 /*-
  * Copyright (c) 1998, 2000, 2001, 2007, 2019, 2020
@@ -71,7 +71,7 @@
 #if 0
 static char sccsid[] = "@(#)vmstat.c   8.2 (Berkeley) 3/1/95";
 #else
-__RCSID("$NetBSD: vmstat.c,v 1.248 2021/11/27 22:16:42 rillig Exp $");
+__RCSID("$NetBSD: vmstat.c,v 1.249 2022/02/01 09:18:07 mrg Exp $");
 #endif
 #endif /* not lint */
 
@@ -569,7 +569,7 @@
 char **
 choosedrives(char **argv)
 {
-       size_t i;
+       size_t i, j, k;
 
        /*
         * Choose drives to be displayed.  Priority goes to (in order) drives
@@ -591,11 +591,30 @@
                        break;
                }
        }
+
+       /*
+        * Pick the most active drives.  Must read the stats once before
+        * sorting so that there is current IO data, before selecting
+        * just the first two drives.
+        */
+       drvreadstats();
        for (i = 0; i < ndrive && ndrives < 2; i++) {
-               if (drv_select[i])
-                       continue;
-               drv_select[i] = 1;
-               ++ndrives;
+               uint64_t high_bytes = 0, bytes;
+
+               k = ndrive;
+               for (j = 0; j < ndrive; j++) {
+                       if (drv_select[j])
+                               continue;
+                       bytes = cur.rbytes[j] + cur.wbytes[j];
+                       if (bytes > high_bytes) {
+                               high_bytes = bytes;
+                               k = j;
+                       }
+               }
+               if (k != ndrive) {
+                       drv_select[k] = 1;
+                       ++ndrives;
+               }
        }
 
        return (argv);