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

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

details:   https://anonhg.NetBSD.org/src/rev/e26776c794d0
branches:  trunk
changeset: 982112:e26776c794d0
user:      simonb <simonb%NetBSD.org@localhost>
date:      Thu Apr 01 06:26:14 2021 +0000

description:
Add a sysctl hashstat collector for vcache.

diffstat:

 sys/kern/vfs_vnode.c |  37 +++++++++++++++++++++++++++++++++++--
 1 files changed, 35 insertions(+), 2 deletions(-)

diffs (65 lines):

diff -r 8bf8db4ed16a -r e26776c794d0 sys/kern/vfs_vnode.c
--- a/sys/kern/vfs_vnode.c      Thu Apr 01 06:25:59 2021 +0000
+++ b/sys/kern/vfs_vnode.c      Thu Apr 01 06:26:14 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_vnode.c,v 1.126 2020/08/04 03:00:10 riastradh Exp $        */
+/*     $NetBSD: vfs_vnode.c,v 1.127 2021/04/01 06:26:14 simonb Exp $   */
 
 /*-
  * Copyright (c) 1997-2011, 2019, 2020 The NetBSD Foundation, Inc.
@@ -148,7 +148,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.126 2020/08/04 03:00:10 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.127 2021/04/01 06:26:14 simonb Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_pax.h"
@@ -1194,6 +1194,38 @@
        return hash;
 }
 
+static int
+vcache_stats(struct hashstat_sysctl *hs, bool fill)
+{
+       vnode_impl_t *vip;
+       uint64_t chain;
+
+       strlcpy(hs->hash_name, "vcache", sizeof(hs->hash_name));
+       strlcpy(hs->hash_desc, "vnode cache hash", sizeof(hs->hash_desc));
+       if (!fill)
+               return 0;
+
+       hs->hash_size = vcache_hashmask + 1;
+
+       for (size_t i = 0; i < hs->hash_size; i++) {
+               chain = 0;
+               mutex_enter(&vcache_lock);
+               SLIST_FOREACH(vip, &vcache_hashtab[i], vi_hash) {
+                       chain++;
+               }
+               mutex_exit(&vcache_lock);
+               if (chain > 0) {
+                       hs->hash_used++;
+                       hs->hash_items += chain;
+                       if (chain > hs->hash_maxchain)
+                               hs->hash_maxchain = chain;
+               }
+               preempt_point();
+       }
+
+       return 0;
+}
+
 static void
 vcache_init(void)
 {
@@ -1206,6 +1238,7 @@
        vcache_hashsize = desiredvnodes;
        vcache_hashtab = hashinit(desiredvnodes, HASH_SLIST, true,
            &vcache_hashmask);
+       hashstat_register("vcache", vcache_stats);
 }
 
 static void