svn commit: r288079 - in stable/10/sys: kern sys
Kirk McKusick
mckusick at FreeBSD.org
Tue Sep 22 00:43:07 UTC 2015
Author: mckusick
Date: Tue Sep 22 00:43:05 2015
New Revision: 288079
URL: https://svnweb.freebsd.org/changeset/base/288079
Log:
MFC of 281677:
More accurately collect name-cache statistics in sysctl functions
sysctl_debug_hashstat_nchash() and sysctl_debug_hashstat_rawnchash().
These changes are in preparation for allowing changes in the size
of the vnode hash tables driven by increases and decreases in the
maximum number of vnodes in the system.
Reviewed by: kib@
Phabric: D2265
MFC of 287497:
Track changes to kern.maxvnodes and appropriately increase or decrease
the size of the name cache hash table (mapping file names to vnodes)
and the vnode hash table (mapping mount point and inode number to vnode).
An appropriate locking strategy is the key to changing hash table sizes
while they are in active use.
Reviewed by: kib
Tested by: Peter Holm
Differential Revision: https://reviews.freebsd.org/D2265
Modified:
stable/10/sys/kern/vfs_cache.c
stable/10/sys/kern/vfs_hash.c
stable/10/sys/kern/vfs_subr.c
stable/10/sys/sys/vnode.h
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/kern/vfs_cache.c
==============================================================================
--- stable/10/sys/kern/vfs_cache.c Mon Sep 21 22:34:16 2015 (r288078)
+++ stable/10/sys/kern/vfs_cache.c Tue Sep 22 00:43:05 2015 (r288079)
@@ -330,23 +330,27 @@ sysctl_debug_hashstat_rawnchash(SYSCTL_H
int n_nchash;
int count;
+retry:
n_nchash = nchash + 1; /* nchash is max index, not count */
if (!req->oldptr)
return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
-
- /* Scan hash tables for applicable entries */
- for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
- CACHE_RLOCK();
- count = 0;
- LIST_FOREACH(ncp, ncpp, nc_hash) {
- count++;
- }
+ cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK);
+ CACHE_RLOCK();
+ if (n_nchash != nchash + 1) {
CACHE_RUNLOCK();
- error = SYSCTL_OUT(req, &count, sizeof(count));
- if (error)
- return (error);
+ free(cntbuf, M_TEMP);
+ goto retry;
}
- return (0);
+ /* Scan hash tables counting entries */
+ for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++)
+ LIST_FOREACH(ncp, ncpp, nc_hash)
+ cntbuf[i]++;
+ CACHE_RUNLOCK();
+ for (error = 0, i = 0; i < n_nchash; i++)
+ if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0)
+ break;
+ free(cntbuf, M_TEMP);
+ return (error);
}
SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD|
CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int",
@@ -935,6 +939,44 @@ nchinit(void *dummy __unused)
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
+void
+cache_changesize(int newmaxvnodes)
+{
+ struct nchashhead *new_nchashtbl, *old_nchashtbl;
+ u_long new_nchash, old_nchash;
+ struct namecache *ncp;
+ uint32_t hash;
+ int i;
+
+ new_nchashtbl = hashinit(newmaxvnodes * 2, M_VFSCACHE, &new_nchash);
+ /* If same hash table size, nothing to do */
+ if (nchash == new_nchash) {
+ free(new_nchashtbl, M_VFSCACHE);
+ return;
+ }
+ /*
+ * Move everything from the old hash table to the new table.
+ * None of the namecache entries in the table can be removed
+ * because to do so, they have to be removed from the hash table.
+ */
+ CACHE_WLOCK();
+ old_nchashtbl = nchashtbl;
+ old_nchash = nchash;
+ nchashtbl = new_nchashtbl;
+ nchash = new_nchash;
+ for (i = 0; i <= old_nchash; i++) {
+ while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) {
+ hash = fnv_32_buf(nc_get_name(ncp), ncp->nc_nlen,
+ FNV1_32_INIT);
+ hash = fnv_32_buf(&ncp->nc_dvp, sizeof(ncp->nc_dvp),
+ hash);
+ LIST_REMOVE(ncp, nc_hash);
+ LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash);
+ }
+ }
+ CACHE_WUNLOCK();
+ free(old_nchashtbl, M_VFSCACHE);
+}
/*
* Invalidate all entries to a particular vnode.
Modified: stable/10/sys/kern/vfs_hash.c
==============================================================================
--- stable/10/sys/kern/vfs_hash.c Mon Sep 21 22:34:16 2015 (r288078)
+++ stable/10/sys/kern/vfs_hash.c Tue Sep 22 00:43:05 2015 (r288079)
@@ -160,3 +160,40 @@ vfs_hash_rehash(struct vnode *vp, u_int
vp->v_hash = hash;
mtx_unlock(&vfs_hash_mtx);
}
+
+void
+vfs_hash_changesize(int newmaxvnodes)
+{
+ struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl;
+ u_long vfs_hash_newmask, vfs_hash_oldmask;
+ struct vnode *vp;
+ int i;
+
+ vfs_hash_newtbl = hashinit(newmaxvnodes, M_VFS_HASH,
+ &vfs_hash_newmask);
+ /* If same hash table size, nothing to do */
+ if (vfs_hash_mask == vfs_hash_newmask) {
+ free(vfs_hash_newtbl, M_VFS_HASH);
+ return;
+ }
+ /*
+ * Move everything from the old hash table to the new table.
+ * None of the vnodes in the table can be recycled because to
+ * do so, they have to be removed from the hash table.
+ */
+ rw_wlock(&vfs_hash_lock);
+ vfs_hash_oldtbl = vfs_hash_tbl;
+ vfs_hash_oldmask = vfs_hash_mask;
+ vfs_hash_tbl = vfs_hash_newtbl;
+ vfs_hash_mask = vfs_hash_newmask;
+ for (i = 0; i <= vfs_hash_oldmask; i++) {
+ while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) {
+ LIST_REMOVE(vp, v_hashlist);
+ LIST_INSERT_HEAD(
+ vfs_hash_bucket(vp->v_mount, vp->v_hash),
+ vp, v_hashlist);
+ }
+ }
+ rw_wunlock(&vfs_hash_lock);
+ free(vfs_hash_oldtbl, M_VFS_HASH);
+}
Modified: stable/10/sys/kern/vfs_subr.c
==============================================================================
--- stable/10/sys/kern/vfs_subr.c Mon Sep 21 22:34:16 2015 (r288078)
+++ stable/10/sys/kern/vfs_subr.c Tue Sep 22 00:43:05 2015 (r288079)
@@ -280,8 +280,25 @@ static enum { SYNCER_RUNNING, SYNCER_SHU
* XXX desiredvnodes is historical cruft and should not exist.
*/
int desiredvnodes;
-SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RW,
- &desiredvnodes, 0, "Maximum number of vnodes");
+
+static int
+sysctl_update_desiredvnodes(SYSCTL_HANDLER_ARGS)
+{
+ int error, old_desiredvnodes;
+
+ old_desiredvnodes = desiredvnodes;
+ if ((error = sysctl_handle_int(oidp, arg1, arg2, req)) != 0)
+ return (error);
+ if (old_desiredvnodes != desiredvnodes) {
+ vfs_hash_changesize(desiredvnodes);
+ cache_changesize(desiredvnodes);
+ }
+ return (0);
+}
+
+SYSCTL_PROC(_kern, KERN_MAXVNODES, maxvnodes,
+ CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, &desiredvnodes, 0,
+ sysctl_update_desiredvnodes, "I", "Maximum number of vnodes");
SYSCTL_ULONG(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
&wantfreevnodes, 0, "Minimum number of vnodes (legacy)");
static int vnlru_nowhere;
Modified: stable/10/sys/sys/vnode.h
==============================================================================
--- stable/10/sys/sys/vnode.h Mon Sep 21 22:34:16 2015 (r288078)
+++ stable/10/sys/sys/vnode.h Tue Sep 22 00:43:05 2015 (r288079)
@@ -600,6 +600,7 @@ struct vnode;
typedef int (*vn_get_ino_t)(struct mount *, void *, int, struct vnode **);
/* cache_* may belong in namei.h. */
+void cache_changesize(int newhashsize);
#define cache_enter(dvp, vp, cnp) \
cache_enter_time(dvp, vp, cnp, NULL, NULL)
void cache_enter_time(struct vnode *dvp, struct vnode *vp,
@@ -836,6 +837,7 @@ int fifo_printinfo(struct vnode *);
/* vfs_hash.c */
typedef int vfs_hash_cmp_t(struct vnode *vp, void *arg);
+void vfs_hash_changesize(int newhashsize);
int vfs_hash_get(const struct mount *mp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);
u_int vfs_hash_index(struct vnode *vp);
int vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);
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