[src/ad-namecache]: src/sys/kern - Fold the "doingcache" conditional into the...

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

details:   https://anonhg.NetBSD.org/src/rev/2def53abe932
branches:  ad-namecache
changeset: 746108:2def53abe932
user:      ad <ad%NetBSD.org@localhost>
date:      Sun Mar 22 00:34:31 2020 +0000

description:
- Fold the "doingcache" conditional into the max length conditional.
- Mark the tunables __read_mostly.

diffstat:

 sys/kern/vfs_cache.c |  27 +++++++++++++--------------
 1 files changed, 13 insertions(+), 14 deletions(-)

diffs (76 lines):

diff -r 8a49d7900b1a -r 2def53abe932 sys/kern/vfs_cache.c
--- a/sys/kern/vfs_cache.c      Sat Mar 21 22:04:17 2020 +0000
+++ b/sys/kern/vfs_cache.c      Sun Mar 22 00:34:31 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_cache.c,v 1.126.2.14 2020/03/21 22:00:55 ad Exp $  */
+/*     $NetBSD: vfs_cache.c,v 1.126.2.15 2020/03/22 00:34:31 ad Exp $  */
 
 /*-
  * Copyright (c) 2008, 2019, 2020 The NetBSD Foundation, Inc.
@@ -171,7 +171,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.126.2.14 2020/03/21 22:00:55 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.126.2.15 2020/03/22 00:34:31 ad Exp $");
 
 #define __NAMECACHE_PRIVATE
 #ifdef _KERNEL_OPT
@@ -235,10 +235,13 @@
        KPREEMPT_ENABLE(l); \
 } while (/* CONSTCOND */ 0);
 
-/* Tunables */
-static const int cache_lru_maxdeact = 2;       /* max # to deactivate */
-static const int cache_lru_maxscan = 64;       /* max # to scan/reclaim */
-static int doingcache = 1;                     /* 1 => enable the cache */
+/*
+ * Tunables.  cache_maxlen replaces the historical doingcache:
+ * set it zero to disable caching for debugging purposes.
+ */
+int cache_lru_maxdeact __read_mostly = 2;      /* max # to deactivate */
+int cache_lru_maxscan __read_mostly = 64;      /* max # to scan/reclaim */
+int cache_maxlen __read_mostly = USHRT_MAX;    /* max name length to cache */
 
 /* sysctl */
 static struct  sysctllog *cache_sysctllog;
@@ -515,11 +518,7 @@
        }
        *vn_ret = NULL;
 
-       if (__predict_false(!doingcache)) {
-               return false;
-       }
-
-       if (__predict_false(namelen > USHRT_MAX)) {
+       if (__predict_false(namelen > cache_maxlen)) {
                SDT_PROBE(vfs, namecache, lookup, toolong, dvp,
                    name, namelen, 0, 0);
                COUNT(ncs_long);
@@ -644,7 +643,7 @@
        *vn_ret = NULL;
 
        /* If disabled, or file system doesn't support this, bail out. */
-       if (__predict_false(!doingcache ||
+       if (__predict_false(cache_maxlen == 0 ||
            (dvp->v_mount->mnt_iflag & IMNT_NCLOOKUP) == 0)) {
                return false;
        }
@@ -753,7 +752,7 @@
 
        KASSERT(vp != NULL);
 
-       if (!doingcache)
+       if (cache_maxlen == 0)
                goto out;
 
        rw_enter(&vi->vi_nc_listlock, RW_READER);
@@ -855,7 +854,7 @@
 
        /* First, check whether we can/should add a cache entry. */
        if ((cnflags & MAKEENTRY) == 0 ||
-           __predict_false(namelen > USHRT_MAX || !doingcache)) {
+           __predict_false(namelen > cache_maxlen)) {
                SDT_PROBE(vfs, namecache, enter, toolong, vp, name, namelen,
                    0, 0);
                return;