[src/trunk]: src/sys/uvm Add a sysctl hashstat collector for ubchash.

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

details:   https://anonhg.NetBSD.org/src/rev/b06789a92585
branches:  trunk
changeset: 960882:b06789a92585
user:      simonb <simonb%NetBSD.org@localhost>
date:      Thu Apr 01 06:26:26 2021 +0000

description:
Add a sysctl hashstat collector for ubchash.

diffstat:

 sys/uvm/uvm_bio.c |  40 ++++++++++++++++++++++++++++++++++++++--
 1 files changed, 38 insertions(+), 2 deletions(-)

diffs (79 lines):

diff -r 4846d7ecc67d -r b06789a92585 sys/uvm/uvm_bio.c
--- a/sys/uvm/uvm_bio.c Thu Apr 01 06:26:14 2021 +0000
+++ b/sys/uvm/uvm_bio.c Thu Apr 01 06:26:26 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_bio.c,v 1.125 2021/03/13 15:29:55 skrll Exp $      */
+/*     $NetBSD: uvm_bio.c,v 1.126 2021/04/01 06:26:26 simonb Exp $     */
 
 /*
  * Copyright (c) 1998 Chuck Silvers.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.125 2021/03/13 15:29:55 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.126 2021/04/01 06:26:26 simonb Exp $");
 
 #include "opt_uvmhist.h"
 #include "opt_ubc.h"
@@ -44,6 +44,7 @@
 #include <sys/kmem.h>
 #include <sys/kernel.h>
 #include <sys/proc.h>
+#include <sys/sysctl.h>
 #include <sys/vnode.h>
 #include <sys/bitops.h>                /* for ilog2() */
 
@@ -61,6 +62,7 @@
 static int     ubc_fault(struct uvm_faultinfo *, vaddr_t, struct vm_page **,
                          int, int, vm_prot_t, int);
 static struct ubc_map *ubc_find_mapping(struct uvm_object *, voff_t);
+static int     ubchash_stats(struct hashstat_sysctl *hs, bool fill);
 #ifdef UBC_USE_PMAP_DIRECT
 static int __noinline ubc_uiomove_direct(struct uvm_object *, struct uio *, vsize_t,
                          int, int);
@@ -215,6 +217,8 @@
                                UVM_ADV_RANDOM, UVM_FLAG_NOMERGE)) != 0) {
                panic("ubc_init: failed to map ubc_object");
        }
+
+       hashstat_register("ubchash", ubchash_stats);
 }
 
 void
@@ -1104,3 +1108,35 @@
        }
        rw_exit(ubc_object.uobj.vmobjlock);
 }
+
+static int
+ubchash_stats(struct hashstat_sysctl *hs, bool fill)
+{
+       struct ubc_map *umap;
+       uint64_t chain;
+
+       strlcpy(hs->hash_name, "ubchash", sizeof(hs->hash_name));
+       strlcpy(hs->hash_desc, "ubc object hash", sizeof(hs->hash_desc));
+       if (!fill)
+               return 0;
+
+       hs->hash_size = ubc_object.hashmask + 1;
+
+       for (size_t i = 0; i < hs->hash_size; i++) {
+               chain = 0;
+               rw_enter(ubc_object.uobj.vmobjlock, RW_READER);
+               LIST_FOREACH(umap, &ubc_object.hash[i], hash) {
+                       chain++;
+               }
+               rw_exit(ubc_object.uobj.vmobjlock);
+               if (chain > 0) {
+                       hs->hash_used++;
+                       hs->hash_items += chain;
+                       if (chain > hs->hash_maxchain)
+                               hs->hash_maxchain = chain;
+               }
+               preempt_point();
+       }
+
+       return 0;
+}