Date: Wed, 30 Apr 1997 18:31:02 +0200 From: Poul-Henning Kamp <phk@dk.tfs.com> To: Doug Rabson <dfr@nlsystems.com> Cc: Poul-Henning Kamp <phk@dk.tfs.com>, current@freebsd.org Subject: Re: vnode->v_usage Message-ID: <207.862417862@critter> In-Reply-To: Your message of "Sun, 27 Apr 1997 14:36:36 BST." <Pine.BSF.3.95q.970427143216.346G-100000@herring.nlsystems.com>
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In message <Pine.BSF.3.95q.970427143216.346G-100000@herring.nlsystems.com>, Dou
g Rabson writes:
>On Sun, 27 Apr 1997, Poul-Henning Kamp wrote:
>>
>> Unless somebody convinces me of the utility of this field, I will remove
>> it from the vnodes.
>>
>I think it is intended to be used to keep frequently used vnodes from
>being recycled by getnewvnode.
Well, I've done it. Here is a patch that implements LRU for name-cache
hits on the vnode freelist. I doubt that it has any performance impact,
but it makes the vnode 4 bytes smaller, which is a good thing.
Please test and report.
Recompile or rename your LKMs before trying this!
Poul-Henning
Index: sys/vnode.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/vnode.h,v
retrieving revision 1.43
diff -u -r1.43 vnode.h
--- vnode.h 1997/04/04 17:43:32 1.43
+++ vnode.h 1997/04/30 16:12:08
@@ -104,7 +104,6 @@
daddr_t v_cstart; /* start block of cluster */
daddr_t v_lasta; /* last allocation */
int v_clen; /* length of current cluster */
- int v_usage; /* Vnode usage counter */
struct vm_object *v_object; /* Place to store VM object */
struct simplelock v_interlock; /* lock on usecount and flag */
struct lock *v_vnlock; /* used for non-locking fs's */
@@ -506,6 +505,7 @@
checkalias __P((struct vnode *vp, dev_t nvp_rdev, struct mount *mp));
void vput __P((struct vnode *vp));
void vrele __P((struct vnode *vp));
+void vtouch __P((struct vnode *vp));
#endif /* KERNEL */
#endif /* !_SYS_VNODE_H_ */
Index: kern/vfs_cache.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/vfs_cache.c,v
retrieving revision 1.24
diff -u -r1.24 vfs_cache.c
--- vfs_cache.c 1997/03/08 15:22:14 1.24
+++ vfs_cache.c 1997/04/30 16:15:56
@@ -187,9 +187,9 @@
if (ncp->nc_vp) {
nchstats.ncs_goodhits++;
TOUCH(ncp);
+ if (!ncp->nc_vp->v_usecount) /* on the freelist, LRU it */
+ vtouch(ncp->nc_vp);
*vpp = ncp->nc_vp;
- if ((*vpp)->v_usage < MAXVNODEUSE)
- (*vpp)->v_usage++;
return (-1);
}
@@ -263,9 +263,9 @@
*/
ncp->nc_vp = vp;
if (vp) {
+ if (!vp->v_usecount) /* on the freelist, LRU it */
+ vtouch(vp);
ncp->nc_vpid = vp->v_id;
- if (vp->v_usage < MAXVNODEUSE)
- ++vp->v_usage;
} else
ncp->nc_vpid = cnp->cn_flags & ISWHITEOUT;
ncp->nc_dvp = dvp;
Index: kern/vfs_subr.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/vfs_subr.c,v
retrieving revision 1.83
diff -u -r1.83 vfs_subr.c
--- vfs_subr.c 1997/04/25 06:47:12 1.83
+++ vfs_subr.c 1997/04/30 16:13:35
@@ -382,12 +382,6 @@
if (vp->v_usecount)
panic("free vnode isn't");
TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
- if (vp->v_usage > 0) {
- simple_unlock(&vp->v_interlock);
- --vp->v_usage;
- TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
- goto retry;
- }
freevnodes--;
/* see comment on why 0xdeadb is set at end of vgone (below) */
@@ -420,7 +414,6 @@
vp->v_clen = 0;
vp->v_socket = 0;
vp->v_writecount = 0; /* XXX */
- vp->v_usage = 0;
}
vp->v_type = VNON;
cache_purge(vp);
@@ -1119,7 +1112,6 @@
simple_lock(&vnode_free_list_slock);
if (vp->v_flag & VAGE) {
vp->v_flag &= ~VAGE;
- vp->v_usage = 0;
if(vp->v_tag != VT_TFS)
TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
} else {
@@ -2146,4 +2138,16 @@
retn:
return error;
+}
+
+void
+vtouch(vp)
+ struct vnode *vp;
+{
+ if (vp->v_usecount)
+ return;
+ simple_lock(&vnode_free_list_slock);
+ TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
+ TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
+ simple_unlock(&vnode_free_list_slock);
}
--
Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team.
http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox.
whois: [PHK] | phk@tfs.com TRW Financial Systems, Inc.
Power and ignorance is a disgusting cocktail.
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