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Add vlruvp() routine - implements LRU operation for vnode recycling.

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We calculate a trigger point that both guarentees we will find a
sufficient number of vnodes to recycle and prevents us from recycling
vnodes with lots of resident pages.  This particular section of
code is designed to recycle vnodes, not do unnecessary frees of
cached VM pages.
This commit is contained in:
Matthew Dillon 2002-01-10 18:31:53 +00:00
parent c644e6e9a8
commit e61ab5fce9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=89238
1 changed files with 46 additions and 0 deletions
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46
sys/kern/vfs_subr.c
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@ -76,12 +76,14 @@ static MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
static void addalias __P((struct vnode *vp, dev_t nvp_rdev));
static void insmntque __P((struct vnode *vp, struct mount *mp));
static void vclean __P((struct vnode *vp, int flags, struct thread *td));
static void vlruvp(struct vnode *vp);
/*
* Number of vnodes in existence. Increased whenever getnewvnode()
* allocates a new vnode, never decreased.
*/
static unsigned long numvnodes;
SYSCTL_LONG(_debug, OID_AUTO, numvnodes, CTLFLAG_RD, &numvnodes, 0, "");
/*
@ -543,6 +545,20 @@ vlrureclaim(struct mount *mp, int count)
{
struct vnode *vp;
int done;
int trigger;
int usevnodes;
/*
* Calculate the trigger point, don't allow user
* screwups to blow us up. This prevents us from
* recycling vnodes with lots of resident pages. We
* aren't trying to free memory, we are trying to
* free vnodes.
*/
usevnodes = desiredvnodes;
if (usevnodes <= 0)
usevnodes = 1;
trigger = cnt.v_page_count * 2 / usevnodes;
done = 0;
mtx_lock(&mntvnode_mtx);
@ -553,6 +569,7 @@ vlrureclaim(struct mount *mp, int count)
if (vp->v_type != VNON &&
vp->v_type != VBAD &&
VMIGHTFREE(vp) && /* critical path opt */
(vp->v_object == NULL || vp->v_object->resident_page_count < trigger) &&
mtx_trylock(&vp->v_interlock)
) {
mtx_unlock(&mntvnode_mtx);
@ -1658,6 +1675,8 @@ vget(vp, flags, td)
vp->v_usecount--;
if (VSHOULDFREE(vp))
vfree(vp);
else
vlruvp(vp);
mtx_unlock(&vp->v_interlock);
}
return (error);
@ -1707,6 +1726,8 @@ vrele(vp)
vp->v_usecount--;
if (VSHOULDFREE(vp))
vfree(vp);
else
vlruvp(vp);
/*
* If we are doing a vput, the node is already locked, and we must
* call VOP_INACTIVE with the node locked. So, in the case of
@ -1754,6 +1775,8 @@ vput(vp)
vp->v_usecount--;
if (VSHOULDFREE(vp))
vfree(vp);
else
vlruvp(vp);
/*
* If we are doing a vput, the node is already locked, and we must
* call VOP_INACTIVE with the node locked. So, in the case of
@ -1802,6 +1825,8 @@ vdrop(vp)
vp->v_holdcnt--;
if (VSHOULDFREE(vp))
vfree(vp);
else
vlruvp(vp);
splx(s);
}
@ -1939,6 +1964,27 @@ vflush(mp, rootrefs, flags)
return (0);
}
/*
* This moves a now (likely recyclable) vnode to the end of the
* mountlist. XXX However, it is temporarily disabled until we
* can clean up ffs_sync() and friends, which have loop restart
* conditions which this code causes to operate O(N^2).
*/
static void
vlruvp(struct vnode *vp)
{
#if 0
struct mount *mp;
if ((mp = vp->v_mount) != NULL) {
mtx_lock(&mntvnode_mtx);
TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
mtx_unlock(&mntvnode_mtx);
}
#endif
}
/*
* Disassociate the underlying file system from a vnode.
*/