[src/trunk]: src/usr.bin/systat sysctlbyname is convenient, but ain't cheap. ...

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

details:   https://anonhg.NetBSD.org/src/rev/211480e7f95a
branches:  trunk
changeset: 818682:211480e7f95a
user:      christos <christos%NetBSD.org@localhost>
date:      Mon Oct 24 00:40:17 2016 +0000

description:
sysctlbyname is convenient, but ain't cheap. Cache it.

diffstat:

 usr.bin/systat/bufcache.c |  15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diffs (38 lines):

diff -r 8fe54012952c -r 211480e7f95a usr.bin/systat/bufcache.c
--- a/usr.bin/systat/bufcache.c Sun Oct 23 21:20:56 2016 +0000
+++ b/usr.bin/systat/bufcache.c Mon Oct 24 00:40:17 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: bufcache.c,v 1.26 2013/10/18 20:47:07 christos Exp $   */
+/*     $NetBSD: bufcache.c,v 1.27 2016/10/24 00:40:17 christos Exp $   */
 
 /*-
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: bufcache.c,v 1.26 2013/10/18 20:47:07 christos Exp $");
+__RCSID("$NetBSD: bufcache.c,v 1.27 2016/10/24 00:40:17 christos Exp $");
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -128,10 +128,17 @@
        double tvalid, tsize;
        struct ml_entry *ml;
        size_t len;
+       static int mib[] = { -1, 0 };
 
+       if (mib[0] == -1) {
+               len = __arraycount(mib);
+               if (sysctlnametomib("vm.bufmem", mib, &len) == -1)
+                       error("can't get \"vm.bufmem\" mib: %s",
+                           strerror(errno));
+       }
        len = sizeof(bufmem);
-       if (sysctlbyname("vm.bufmem", &bufmem, &len, NULL, 0))
-               error("can't get \"vm.bufmmem\": %s", strerror(errno));
+       if (sysctl(mib, 2, &bufmem, &len, NULL, 0) == -1)
+               error("can't get \"vm.bufmem\": %s", strerror(errno));
 
        mvwprintw(wnd, 0, 0,
            "   %*d metadata buffers using             %*"PRIu64" kBytes of "