[src/trunk]: src/sys/kern Add a sysctl hashstat collector for uihash.

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

details:   https://anonhg.NetBSD.org/src/rev/3717fd0d95ce
branches:  trunk
changeset: 1020145:3717fd0d95ce
user:      simonb <simonb%NetBSD.org@localhost>
date:      Thu Apr 01 06:25:45 2021 +0000

description:
Add a sysctl hashstat collector for uihash.

diffstat:

 sys/kern/kern_uidinfo.c |  36 ++++++++++++++++++++++++++++++++++--
 1 files changed, 34 insertions(+), 2 deletions(-)

diffs (64 lines):

diff -r 28e457ae5069 -r 3717fd0d95ce sys/kern/kern_uidinfo.c
--- a/sys/kern/kern_uidinfo.c   Thu Apr 01 06:23:14 2021 +0000
+++ b/sys/kern/kern_uidinfo.c   Thu Apr 01 06:25:45 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_uidinfo.c,v 1.11 2019/03/01 03:03:19 christos Exp $       */
+/*     $NetBSD: kern_uidinfo.c,v 1.12 2021/04/01 06:25:45 simonb Exp $ */
 
 /*-
  * Copyright (c) 1982, 1986, 1991, 1993
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_uidinfo.c,v 1.11 2019/03/01 03:03:19 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_uidinfo.c,v 1.12 2021/04/01 06:25:45 simonb Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -132,6 +132,37 @@
                       CTL_CREATE, CTL_EOL);
 }
 
+static int
+uid_stats(struct hashstat_sysctl *hs, bool fill)
+{
+       struct uidinfo *uip;
+       uint64_t chain;
+
+       strlcpy(hs->hash_name, "uihash", sizeof(hs->hash_name));
+       strlcpy(hs->hash_desc, "user info (uid->used proc) hash",
+           sizeof(hs->hash_desc));
+       if (!fill)
+               return 0;
+
+       hs->hash_size = uihash + 1;
+
+       for (size_t i = 0; i < hs->hash_size; i++) {
+               chain = 0;
+               SLIST_FOREACH(uip, &uihashtbl[i], ui_hash) {
+                       membar_datadep_consumer();
+                       chain++;
+               }
+               if (chain > 0) {
+                       hs->hash_used++;
+                       hs->hash_items += chain;
+                       if (chain > hs->hash_maxchain)
+                               hs->hash_maxchain = chain;
+               }
+       }
+
+       return 0;
+}
+
 void
 uid_init(void)
 {
@@ -151,6 +182,7 @@
         */
        (void)uid_find(0);
        sysctl_kern_uidinfo_setup();
+       hashstat_register("uihash", uid_stats);
 }
 
 struct uidinfo *