[src/trunk]: src/sys/kern Make the stat mutex a leaf. XXX Use atomic counters.

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

details:   https://anonhg.NetBSD.org/src/rev/e264a43cabaf
branches:  trunk
changeset: 796703:e264a43cabaf
user:      joerg <joerg%NetBSD.org@localhost>
date:      Sat Jun 14 16:12:34 2014 +0000

description:
Make the stat mutex a leaf. XXX Use atomic counters.

diffstat:

 sys/kern/vfs_cache.c |  30 ++++++++++++++++++++----------
 1 files changed, 20 insertions(+), 10 deletions(-)

diffs (153 lines):

diff -r 61aae5b7bb1e -r e264a43cabaf sys/kern/vfs_cache.c
--- a/sys/kern/vfs_cache.c      Sat Jun 14 14:32:43 2014 +0000
+++ b/sys/kern/vfs_cache.c      Sat Jun 14 16:12:34 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_cache.c,v 1.97 2014/06/03 21:16:15 joerg Exp $     */
+/*     $NetBSD: vfs_cache.c,v 1.98 2014/06/14 16:12:34 joerg Exp $     */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -58,7 +58,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.97 2014/06/03 21:16:15 joerg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.98 2014/06/14 16:12:34 joerg Exp $");
 
 #include "opt_ddb.h"
 #include "opt_revcache.h"
@@ -388,8 +388,8 @@
        }
 
        cpup = curcpu()->ci_data.cpu_nch;
-       mutex_enter(&cpup->cpu_lock);
        if (__predict_false(namelen > NCHNAMLEN)) {
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_long);
                mutex_exit(&cpup->cpu_lock);
                /* found nothing */
@@ -397,13 +397,16 @@
        }
        ncp = cache_lookup_entry(dvp, name, namelen);
        if (__predict_false(ncp == NULL)) {
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_miss);
                mutex_exit(&cpup->cpu_lock);
                /* found nothing */
                return 0;
        }
        if ((cnflags & MAKEENTRY) == 0) {
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_badhits);
+               mutex_exit(&cpup->cpu_lock);
                /*
                 * Last component and we are renaming or deleting,
                 * the cache entry is invalid, or otherwise don't
@@ -411,7 +414,6 @@
                 */
                cache_invalidate(ncp);
                mutex_exit(&ncp->nc_lock);
-               mutex_exit(&cpup->cpu_lock);
                /* found nothing */
                return 0;
        }
@@ -428,13 +430,16 @@
 
                if (__predict_true(nameiop != CREATE ||
                    (cnflags & ISLASTCN) == 0)) {
+                       mutex_enter(&cpup->cpu_lock);
                        COUNT(cpup->cpu_stats, ncs_neghits);
+                       mutex_exit(&cpup->cpu_lock);
                        mutex_exit(&ncp->nc_lock);
-                       mutex_exit(&cpup->cpu_lock);
                        /* found neg entry; vn is already null from above */
                        return 1;
                } else {
+                       mutex_enter(&cpup->cpu_lock);
                        COUNT(cpup->cpu_stats, ncs_badhits);
+                       mutex_exit(&cpup->cpu_lock);
                        /*
                         * Last component and we are renaming or
                         * deleting, the cache entry is invalid,
@@ -443,7 +448,6 @@
                         */
                        cache_invalidate(ncp);
                        mutex_exit(&ncp->nc_lock);
-                       mutex_exit(&cpup->cpu_lock);
                        /* found nothing */
                        return 0;
                }
@@ -452,7 +456,6 @@
        vp = ncp->nc_vp;
        mutex_enter(vp->v_interlock);
        mutex_exit(&ncp->nc_lock);
-       mutex_exit(&cpup->cpu_lock);
        error = vget(vp, LK_NOWAIT);
        if (error) {
                KASSERT(error == EBUSY);
@@ -460,7 +463,9 @@
                 * This vnode is being cleaned out.
                 * XXX badhits?
                 */
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_falsehits);
+               mutex_exit(&cpup->cpu_lock);
                /* found nothing */
                return 0;
        }
@@ -474,7 +479,9 @@
 #endif /* DEBUG */
 
        /* We don't have the right lock, but this is only for stats. */
+       mutex_enter(&cpup->cpu_lock);
        COUNT(cpup->cpu_stats, ncs_goodhits);
+       mutex_exit(&cpup->cpu_lock);
 
        /* found it */
        *vn_ret = vp;
@@ -503,8 +510,8 @@
        }
 
        cpup = curcpu()->ci_data.cpu_nch;
-       mutex_enter(&cpup->cpu_lock);
        if (__predict_false(namelen > NCHNAMLEN)) {
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_long);
                mutex_exit(&cpup->cpu_lock);
                /* found nothing */
@@ -512,6 +519,7 @@
        }
        ncp = cache_lookup_entry(dvp, name, namelen);
        if (__predict_false(ncp == NULL)) {
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_miss);
                mutex_exit(&cpup->cpu_lock);
                /* found nothing */
@@ -527,15 +535,15 @@
                        /*cnp->cn_flags |= ncp->nc_flags;*/
                        *iswht_ret = (ncp->nc_flags & ISWHITEOUT) != 0;
                }
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_neghits);
+               mutex_exit(&cpup->cpu_lock);
                mutex_exit(&ncp->nc_lock);
-               mutex_exit(&cpup->cpu_lock);
                /* found negative entry; vn is already null from above */
                return 1;
        }
        mutex_enter(vp->v_interlock);
        mutex_exit(&ncp->nc_lock);
-       mutex_exit(&cpup->cpu_lock);
        error = vget(vp, LK_NOWAIT);
        if (error) {
                KASSERT(error == EBUSY);
@@ -543,7 +551,9 @@
                 * This vnode is being cleaned out.
                 * XXX badhits?
                 */
+               mutex_enter(&cpup->cpu_lock);
                COUNT(cpup->cpu_stats, ncs_falsehits);
+               mutex_exit(&cpup->cpu_lock);
                /* found nothing */
                return 0;
        }