Module Name: src
Committed By: ad
Date: Sun Dec 1 18:31:19 UTC 2019
Modified Files:
src/sys/kern: vfs_cache.c
src/sys/sys: namei.src
Log Message:
Back out previous temporarily - seeing unusual lookup failures. Will
come back to it.
To generate a diff of this commit:
cvs rdiff -u -r1.124 -r1.125 src/sys/kern/vfs_cache.c
cvs rdiff -u -r1.45 -r1.46 src/sys/sys/namei.src
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/vfs_cache.c
diff -u src/sys/kern/vfs_cache.c:1.124 src/sys/kern/vfs_cache.c:1.125
--- src/sys/kern/vfs_cache.c:1.124 Sun Dec 1 13:39:53 2019
+++ src/sys/kern/vfs_cache.c Sun Dec 1 18:31:19 2019
@@ -1,7 +1,7 @@
-/* $NetBSD: vfs_cache.c,v 1.124 2019/12/01 13:39:53 ad Exp $ */
+/* $NetBSD: vfs_cache.c,v 1.125 2019/12/01 18:31:19 ad Exp $ */
/*-
- * Copyright (c) 2008, 2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -58,7 +58,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.124 2019/12/01 13:39:53 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.125 2019/12/01 18:31:19 ad Exp $");
#define __NAMECACHE_PRIVATE
#ifdef _KERNEL_OPT
@@ -130,7 +130,7 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,
* - Invalidate: active--->queued
*
* Done by cache_invalidate. If not already invalidated, nullify
- * ncp->nc_dvp and ncp->nc_vp, and add to namecache_gc_queue. Called,
+ * ncp->nc_dvp and ncp->nc_vp, and add to cache_gcqueue. Called,
* among various other places, in cache_lookup(dvp, name, namelen,
* nameiop, cnflags, &iswht, &vp) when MAKEENTRY is missing from
* cnflags.
@@ -145,17 +145,16 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,
* Locking.
*
* L namecache_lock Global lock for namecache table and queues.
- * G namecache_gc_lock Global lock for garbage collection.
* C struct nchcpu::cpu_lock Per-CPU lock to reduce read contention.
- * N struct namecache::nc_lock Per-entry lock, matching nc_vp->v_interlock.
- * If nc_vp==NULL, lock is private / not shared.
+ * N struct namecache::nc_lock Per-entry lock.
+ * V struct vnode::v_interlock Vnode interlock.
*
- * Lock order: L -> C -> N
+ * Lock order: L -> C -> N -> V
*
* Examples:
* . L->C: cache_reclaim
- * . C->N: cache_lookup
- * . L->N: cache_purge1, cache_revlookup
+ * . C->N->V: cache_lookup
+ * . L->N->V: cache_purge1, cache_revlookup
*
* All use serialized by namecache_lock:
*
@@ -168,9 +167,8 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,
* - Insertion serialized by namecache_lock,
* - read protected by per-CPU lock,
* - insert/read ordering guaranteed by memory barriers, and
- * - deletion allowed only under namecache_lock, with namecache_gc_lock
- * taken to chop out the garbage collection list, and *all* per-CPU locks
- * observed as "unowned" at least once:
+ * - deletion allowed only under namecache_lock and *all* per-CPU locks
+ * in CPU_INFO_FOREACH order:
*
* nchashtbl / struct namecache::nc_hash
*
@@ -182,13 +180,11 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,
*
* struct namecache::nc_dvp
* struct namecache::nc_vp
- * struct namecache::nc_hittime (*)
+ * struct namecache::nc_gcqueue (*)
+ * struct namecache::nc_hittime (**)
*
- * All use serialized by struct namecache_gc_lock:
- *
- * struct namecache::nc_gclist
- *
- * (*) cache_prune reads nc_hittime unlocked, since approximate is OK.
+ * (*) Once on the queue, only cache_thread uses this nc_gcqueue, unlocked.
+ * (**) cache_prune reads nc_hittime unlocked, since approximate is OK.
*
* Unlocked because stable after initialization:
*
@@ -261,7 +257,7 @@ typedef u_long nchash_t;
* Structures associated with name cacheing.
*/
-static kmutex_t namecache_lock __cacheline_aligned;
+static kmutex_t *namecache_lock __read_mostly;
static pool_cache_t namecache_cache __read_mostly;
static TAILQ_HEAD(, namecache) nclruhead __cacheline_aligned;
@@ -280,9 +276,8 @@ static u_long ncvhash __read_mostly;
static long numcache __cacheline_aligned;
/* Garbage collection queue and number of entries pending in it. */
-static kmutex_t namecache_gc_lock __cacheline_aligned;
-static SLIST_HEAD(namecache_gc_queue, namecache) namecache_gc_queue;
-static u_int namecache_gc_pend;
+static void *cache_gcqueue;
+static u_int cache_gcpend;
/* Cache effectiveness statistics. This holds total from per-cpu stats */
struct nchstats nchstats __cacheline_aligned;
@@ -292,6 +287,8 @@ struct nchstats nchstats __cacheline_ali
* values and add current per-cpu increments to the subsystem total
* last collected by cache_reclaim().
*/
+#define CACHE_STATS_CURRENT /* nothing */
+
#define COUNT(cpup, f) ((cpup)->cpu_stats.f++)
#define UPDATE(cpup, f) do { \
@@ -301,10 +298,15 @@ struct nchstats nchstats __cacheline_ali
Xcpup->cpu_stats_last.f = Xcnt; \
} while (/* CONSTCOND */ 0)
+#define ADD(stats, cpup, f) do { \
+ struct nchcpu *Xcpup = (cpup); \
+ stats.f += Xcpup->cpu_stats.f - Xcpup->cpu_stats_last.f; \
+} while (/* CONSTCOND */ 0)
+
/* Do unlocked stats the same way. Use a different name to allow mind changes */
#define COUNT_UNL(cpup, f) COUNT((cpup), f)
-static const int cache_lowat = 97;
+static const int cache_lowat = 95;
static const int cache_hiwat = 98;
static const int cache_hottime = 5; /* number of seconds */
static int doingcache = 1; /* 1 => enable the cache */
@@ -367,12 +369,15 @@ cache_hash(const char *name, size_t name
/*
* Invalidate a cache entry and enqueue it for garbage collection.
+ * The caller needs to hold namecache_lock or a per-cpu lock to hold
+ * off cache_reclaim().
*/
static void
cache_invalidate(struct namecache *ncp)
{
+ void *head;
- KASSERT(mutex_owned(ncp->nc_lock));
+ KASSERT(mutex_owned(&ncp->nc_lock));
if (ncp->nc_dvp != NULL) {
SDT_PROBE(vfs, namecache, invalidate, done, ncp->nc_dvp,
@@ -380,10 +385,11 @@ cache_invalidate(struct namecache *ncp)
ncp->nc_vp = NULL;
ncp->nc_dvp = NULL;
- mutex_enter(&namecache_gc_lock);
- SLIST_INSERT_HEAD(&namecache_gc_queue, ncp, nc_gclist);
- namecache_gc_pend++;
- mutex_exit(&namecache_gc_lock);
+ do {
+ head = cache_gcqueue;
+ ncp->nc_gcqueue = head;
+ } while (atomic_cas_ptr(&cache_gcqueue, head, ncp) != head);
+ atomic_inc_uint(&cache_gcpend);
}
}
@@ -395,7 +401,7 @@ static void
cache_disassociate(struct namecache *ncp)
{
- KASSERT(mutex_owned(&namecache_lock));
+ KASSERT(mutex_owned(namecache_lock));
KASSERT(ncp->nc_dvp == NULL);
if (ncp->nc_lru.tqe_prev != NULL) {
@@ -418,8 +424,7 @@ cache_disassociate(struct namecache *ncp
/*
* Lock all CPUs to prevent any cache lookup activity. Conceptually,
- * this locks out all "readers". This is a very heavyweight operation
- * that we only use for nchreinit().
+ * this locks out all "readers".
*/
static void
cache_lock_cpus(void)
@@ -428,9 +433,6 @@ cache_lock_cpus(void)
struct cpu_info *ci;
struct nchcpu *cpup;
- /* Not necessary but don't want more than one LWP trying this. */
- KASSERT(mutex_owned(&namecache_lock));
-
/*
* Lock out all CPUs first, then harvest per-cpu stats. This
* is probably not quite as cache-efficient as doing the lock
@@ -483,7 +485,6 @@ cache_lookup_entry(const struct vnode *d
struct nchashhead *ncpp;
struct namecache *ncp;
nchash_t hash;
- int ticks;
KASSERT(dvp != NULL);
hash = cache_hash(name, namelen);
@@ -495,22 +496,15 @@ cache_lookup_entry(const struct vnode *d
ncp->nc_nlen != namelen ||
memcmp(ncp->nc_name, name, (u_int)ncp->nc_nlen))
continue;
- mutex_enter(ncp->nc_lock);
+ mutex_enter(&ncp->nc_lock);
if (__predict_true(ncp->nc_dvp == dvp)) {
- ticks = hardclock_ticks;
- if (ncp->nc_hittime != ticks) {
- /*
- * Avoid false sharing on MP: do not store
- * to *ncp unless the value changed.
- */
- ncp->nc_hittime = ticks;
- }
+ ncp->nc_hittime = hardclock_ticks;
SDT_PROBE(vfs, namecache, lookup, hit, dvp,
name, namelen, 0, 0);
return ncp;
}
/* Raced: entry has been nullified. */
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
}
SDT_PROBE(vfs, namecache, lookup, miss, dvp,
@@ -579,6 +573,7 @@ cache_lookup(struct vnode *dvp, const ch
int error;
bool hit;
+
/* Establish default result values */
if (iswht_ret != NULL) {
*iswht_ret = 0;
@@ -615,13 +610,12 @@ cache_lookup(struct vnode *dvp, const ch
* want cache entry to exist.
*/
cache_invalidate(ncp);
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
mutex_exit(&cpup->cpu_lock);
/* found nothing */
return false;
}
- vp = ncp->nc_vp;
- if (__predict_false(vp == NULL)) {
+ if (ncp->nc_vp == NULL) {
if (iswht_ret != NULL) {
/*
* Restore the ISWHITEOUT flag saved earlier.
@@ -648,11 +642,14 @@ cache_lookup(struct vnode *dvp, const ch
/* found nothing */
hit = false;
}
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
mutex_exit(&cpup->cpu_lock);
return hit;
}
- KASSERT(vp->v_interlock == ncp->nc_lock);
+
+ vp = ncp->nc_vp;
+ mutex_enter(vp->v_interlock);
+ mutex_exit(&ncp->nc_lock);
mutex_exit(&cpup->cpu_lock);
/*
@@ -727,12 +724,13 @@ cache_lookup_raw(struct vnode *dvp, cons
*iswht_ret = (ncp->nc_flags & ISWHITEOUT) != 0;
}
COUNT(cpup, ncs_neghits);
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
mutex_exit(&cpup->cpu_lock);
/* found negative entry; vn is already null from above */
return true;
}
- KASSERT(vp->v_interlock == ncp->nc_lock);
+ mutex_enter(vp->v_interlock);
+ mutex_exit(&ncp->nc_lock);
mutex_exit(&cpup->cpu_lock);
/*
@@ -777,7 +775,6 @@ cache_revlookup(struct vnode *vp, struct
struct nchcpu *cpup;
char *bp;
int error, nlen;
- bool locked, again;
if (!doingcache)
goto out;
@@ -790,12 +787,10 @@ cache_revlookup(struct vnode *vp, struct
* is the only place these counters are incremented so no one
* will be racing with us to increment them.
*/
- again = false;
- retry:
cpup = curcpu()->ci_data.cpu_nch;
- mutex_enter(&namecache_lock);
+ mutex_enter(namecache_lock);
LIST_FOREACH(ncp, nvcpp, nc_vhash) {
- mutex_enter(ncp->nc_lock);
+ mutex_enter(&ncp->nc_lock);
if (ncp->nc_vp == vp &&
(dvp = ncp->nc_dvp) != NULL &&
dvp != vp) { /* avoid pesky . entries.. */
@@ -818,8 +813,8 @@ cache_revlookup(struct vnode *vp, struct
bp -= nlen;
if (bp <= bufp) {
*dvpp = NULL;
- mutex_exit(ncp->nc_lock);
- mutex_exit(&namecache_lock);
+ mutex_exit(&ncp->nc_lock);
+ mutex_exit(namecache_lock);
SDT_PROBE(vfs, namecache, revlookup,
fail, vp, ERANGE, 0, 0, 0);
return (ERANGE);
@@ -828,18 +823,9 @@ cache_revlookup(struct vnode *vp, struct
*bpp = bp;
}
-
- KASSERT(ncp->nc_lock != dvp->v_interlock);
- locked = mutex_tryenter(dvp->v_interlock);
- mutex_exit(ncp->nc_lock);
- mutex_exit(&namecache_lock);
- if (!locked) {
- if (again) {
- kpause("nchrace", false, 1, NULL);
- }
- again = true;
- goto retry;
- }
+ mutex_enter(dvp->v_interlock);
+ mutex_exit(&ncp->nc_lock);
+ mutex_exit(namecache_lock);
error = vcache_tryvget(dvp);
if (error) {
KASSERT(error == EBUSY);
@@ -855,10 +841,10 @@ cache_revlookup(struct vnode *vp, struct
0, 0, 0);
return (0);
}
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
}
COUNT(cpup, ncs_revmiss);
- mutex_exit(&namecache_lock);
+ mutex_exit(namecache_lock);
out:
*dvpp = NULL;
return (-1);
@@ -887,10 +873,10 @@ cache_enter(struct vnode *dvp, struct vn
SDT_PROBE(vfs, namecache, enter, done, vp, name, namelen, 0, 0);
if (numcache > desiredvnodes) {
- mutex_enter(&namecache_lock);
+ mutex_enter(namecache_lock);
cache_ev_forced.ev_count++;
cache_reclaim();
- mutex_exit(&namecache_lock);
+ mutex_exit(namecache_lock);
}
if (namelen > NCHNAMLEN) {
@@ -899,7 +885,7 @@ cache_enter(struct vnode *dvp, struct vn
} else
ncp = pool_cache_get(namecache_cache, PR_WAITOK);
- mutex_enter(&namecache_lock);
+ mutex_enter(namecache_lock);
numcache++;
/*
@@ -909,27 +895,24 @@ cache_enter(struct vnode *dvp, struct vn
oncp = cache_lookup_entry(dvp, name, namelen);
if (oncp) {
cache_invalidate(oncp);
- mutex_exit(oncp->nc_lock);
+ mutex_exit(&oncp->nc_lock);
}
/* Grab the vnode we just found. */
+ mutex_enter(&ncp->nc_lock);
ncp->nc_vp = vp;
ncp->nc_flags = 0;
ncp->nc_hittime = 0;
+ ncp->nc_gcqueue = NULL;
if (vp == NULL) {
/*
* For negative hits, save the ISWHITEOUT flag so we can
* restore it later when the cache entry is used again.
*/
ncp->nc_flags = cnflags & ISWHITEOUT;
- ncp->nc_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
- } else {
- ncp->nc_lock = vp->v_interlock;
- mutex_obj_hold(ncp->nc_lock);
}
/* Fill in cache info. */
- mutex_enter(ncp->nc_lock);
ncp->nc_dvp = dvp;
LIST_INSERT_HEAD(&VNODE_TO_VIMPL(dvp)->vi_dnclist, ncp, nc_dvlist);
if (vp)
@@ -976,8 +959,8 @@ cache_enter(struct vnode *dvp, struct vn
nvcpp = &ncvhashtbl[NCVHASH(vp)];
LIST_INSERT_HEAD(nvcpp, ncp, nc_vhash);
}
- mutex_exit(ncp->nc_lock);
- mutex_exit(&namecache_lock);
+ mutex_exit(&ncp->nc_lock);
+ mutex_exit(namecache_lock);
}
/*
@@ -994,8 +977,8 @@ nchinit(void)
cache_dtor, NULL);
KASSERT(namecache_cache != NULL);
- mutex_init(&namecache_lock, MUTEX_DEFAULT, IPL_NONE);
- mutex_init(&namecache_gc_lock, MUTEX_DEFAULT, IPL_NONE);
+ namecache_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
+
nchashtbl = hashinit(desiredvnodes, HASH_LIST, true, &nchash);
ncvhashtbl =
#ifdef NAMECACHE_ENTER_REVERSE
@@ -1026,6 +1009,10 @@ nchinit(void)
static int
cache_ctor(void *arg, void *obj, int flag)
{
+ struct namecache *ncp;
+
+ ncp = obj;
+ mutex_init(&ncp->nc_lock, MUTEX_DEFAULT, IPL_NONE);
return 0;
}
@@ -1033,7 +1020,10 @@ cache_ctor(void *arg, void *obj, int fla
static void
cache_dtor(void *arg, void *obj)
{
+ struct namecache *ncp;
+ ncp = obj;
+ mutex_destroy(&ncp->nc_lock);
}
/*
@@ -1070,7 +1060,7 @@ nchreinit(void)
#else
hashinit(desiredvnodes/8, HASH_LIST, true, &mask2);
#endif
- mutex_enter(&namecache_lock);
+ mutex_enter(namecache_lock);
cache_lock_cpus();
oldhash1 = nchashtbl;
oldmask1 = nchash;
@@ -1093,7 +1083,7 @@ nchreinit(void)
}
}
cache_unlock_cpus();
- mutex_exit(&namecache_lock);
+ mutex_exit(namecache_lock);
hashdone(oldhash1, HASH_LIST, oldmask1);
hashdone(oldhash2, HASH_LIST, oldmask2);
}
@@ -1107,16 +1097,16 @@ cache_purge1(struct vnode *vp, const cha
{
struct namecache *ncp, *ncnext;
- mutex_enter(&namecache_lock);
+ mutex_enter(namecache_lock);
if (flags & PURGE_PARENTS) {
SDT_PROBE(vfs, namecache, purge, parents, vp, 0, 0, 0, 0);
for (ncp = LIST_FIRST(&VNODE_TO_VIMPL(vp)->vi_nclist);
ncp != NULL; ncp = ncnext) {
ncnext = LIST_NEXT(ncp, nc_vlist);
- mutex_enter(ncp->nc_lock);
+ mutex_enter(&ncp->nc_lock);
cache_invalidate(ncp);
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
cache_disassociate(ncp);
}
}
@@ -1125,9 +1115,9 @@ cache_purge1(struct vnode *vp, const cha
for (ncp = LIST_FIRST(&VNODE_TO_VIMPL(vp)->vi_dnclist);
ncp != NULL; ncp = ncnext) {
ncnext = LIST_NEXT(ncp, nc_dvlist);
- mutex_enter(ncp->nc_lock);
+ mutex_enter(&ncp->nc_lock);
cache_invalidate(ncp);
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
cache_disassociate(ncp);
}
}
@@ -1136,11 +1126,11 @@ cache_purge1(struct vnode *vp, const cha
ncp = cache_lookup_entry(vp, name, namelen);
if (ncp) {
cache_invalidate(ncp);
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
cache_disassociate(ncp);
}
}
- mutex_exit(&namecache_lock);
+ mutex_exit(namecache_lock);
}
/*
@@ -1153,19 +1143,19 @@ cache_purgevfs(struct mount *mp)
struct namecache *ncp, *nxtcp;
SDT_PROBE(vfs, namecache, purge, vfs, mp, 0, 0, 0, 0);
- mutex_enter(&namecache_lock);
+ mutex_enter(namecache_lock);
for (ncp = TAILQ_FIRST(&nclruhead); ncp != NULL; ncp = nxtcp) {
nxtcp = TAILQ_NEXT(ncp, nc_lru);
- mutex_enter(ncp->nc_lock);
+ mutex_enter(&ncp->nc_lock);
if (ncp->nc_dvp != NULL && ncp->nc_dvp->v_mount == mp) {
/* Free the resources we had. */
cache_invalidate(ncp);
cache_disassociate(ncp);
}
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
}
cache_reclaim();
- mutex_exit(&namecache_lock);
+ mutex_exit(namecache_lock);
}
/*
@@ -1180,7 +1170,7 @@ cache_prune(int incache, int target)
struct namecache *ncp, *nxtcp, *sentinel;
int items, recent, tryharder;
- KASSERT(mutex_owned(&namecache_lock));
+ KASSERT(mutex_owned(namecache_lock));
SDT_PROBE(vfs, namecache, prune, done, incache, target, 0, 0, 0);
items = 0;
@@ -1208,13 +1198,13 @@ cache_prune(int incache, int target)
TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
continue;
}
- mutex_enter(ncp->nc_lock);
+ mutex_enter(&ncp->nc_lock);
if (ncp->nc_dvp != NULL) {
cache_invalidate(ncp);
cache_disassociate(ncp);
incache--;
}
- mutex_exit(ncp->nc_lock);
+ mutex_exit(&ncp->nc_lock);
}
cache_ev_scan.ev_count += items;
}
@@ -1225,21 +1215,17 @@ cache_prune(int incache, int target)
static void
cache_reclaim(void)
{
- CPU_INFO_ITERATOR cii;
- struct cpu_info *ci;
- struct nchcpu *cpup;
- struct namecache_gc_queue queue;
struct namecache *ncp, *next;
int items;
- KASSERT(mutex_owned(&namecache_lock));
+ KASSERT(mutex_owned(namecache_lock));
/*
* If the number of extant entries not awaiting garbage collection
* exceeds the high water mark, then reclaim stale entries until we
* reach our low water mark.
*/
- items = numcache - namecache_gc_pend;
+ items = numcache - cache_gcpend;
if (items > (uint64_t)desiredvnodes * cache_hiwat / 100) {
cache_prune(items, (int)((uint64_t)desiredvnodes *
cache_lowat / 100));
@@ -1247,73 +1233,31 @@ cache_reclaim(void)
} else
cache_ev_under.ev_count++;
- /* Chop the existing garbage collection list out. */
- mutex_enter(&namecache_gc_lock);
- queue = namecache_gc_queue;
- items = namecache_gc_pend;
- SLIST_INIT(&namecache_gc_queue);
- namecache_gc_pend = 0;
- mutex_exit(&namecache_gc_lock);
-
/*
- * Now disassociate all entries. We haven't locked out the reader
- * side (cache_lookup_entry()) but the "next" pointers in the hash
- * list will remain sufficiently consitent regardless of which
- * version of the list the reader sees (see defs of LIST_FOREACH,
- * LIST_NEXT);
+ * Stop forward lookup activity on all CPUs and garbage collect dead
+ * entries.
*/
- SLIST_FOREACH(ncp, &queue, nc_gclist) {
+ cache_lock_cpus();
+ ncp = cache_gcqueue;
+ cache_gcqueue = NULL;
+ items = cache_gcpend;
+ cache_gcpend = 0;
+ while (ncp != NULL) {
+ next = ncp->nc_gcqueue;
cache_disassociate(ncp);
KASSERT(ncp->nc_dvp == NULL);
if (ncp->nc_hash.le_prev != NULL) {
LIST_REMOVE(ncp, nc_hash);
ncp->nc_hash.le_prev = NULL;
}
- }
-
- /*
- * With that done, make sure our updates are visible on the bus, and
- * make a pass to observe the status of all of the CPU locks. If we
- * see a lock is unheld, we know the garbage collected entries can
- * no longer visible to that CPU. If we see a lock IS held, we need
- * to acquire and release it once to make sure that CPU is out of
- * cache_lookup_entry(). Take the opportunity to refresh stats.
- */
- membar_sync(); /* stores above vs. reads below */
- for (CPU_INFO_FOREACH(cii, ci)) {
- cpup = ci->ci_data.cpu_nch;
- if (__predict_false(mutex_owner(&cpup->cpu_lock) != NULL)) {
- mutex_enter(&cpup->cpu_lock);
- /* nothing */
- mutex_exit(&cpup->cpu_lock);
- }
- UPDATE(cpup, ncs_goodhits);
- UPDATE(cpup, ncs_neghits);
- UPDATE(cpup, ncs_badhits);
- UPDATE(cpup, ncs_falsehits);
- UPDATE(cpup, ncs_miss);
- UPDATE(cpup, ncs_long);
- UPDATE(cpup, ncs_pass2);
- UPDATE(cpup, ncs_2passes);
- UPDATE(cpup, ncs_revhits);
- UPDATE(cpup, ncs_revmiss);
- }
- membar_sync(); /* reads above vs. stores below */
-
- /*
- * Nobody else can see the cache entries any more. Make a final
- * pass over the list and toss the contents.
- */
- SLIST_FOREACH_SAFE(ncp, &queue, nc_gclist, next) {
- mutex_obj_free(ncp->nc_lock);
- ncp->nc_lock = NULL;
if (ncp->nc_nlen > NCHNAMLEN) {
cache_dtor(NULL, ncp);
kmem_free(ncp, sizeof(*ncp) + ncp->nc_nlen);
} else
pool_cache_put(namecache_cache, ncp);
+ ncp = next;
}
-
+ cache_unlock_cpus();
numcache -= items;
cache_ev_gc.ev_count += items;
}
@@ -1329,10 +1273,10 @@ static void
cache_thread(void *arg)
{
- mutex_enter(&namecache_lock);
+ mutex_enter(namecache_lock);
for (;;) {
cache_reclaim();
- kpause("cachegc", false, hz, &namecache_lock);
+ kpause("cachegc", false, hz, namecache_lock);
}
}
@@ -1386,40 +1330,53 @@ namecache_count_2passes(void)
static int
cache_stat_sysctl(SYSCTLFN_ARGS)
{
+ struct nchstats stats;
+ struct nchcpu *my_cpup;
+#ifdef CACHE_STATS_CURRENT
CPU_INFO_ITERATOR cii;
struct cpu_info *ci;
+#endif /* CACHE_STATS_CURRENT */
if (oldp == NULL) {
- *oldlenp = sizeof(nchstats);
+ *oldlenp = sizeof(stats);
return 0;
}
- if (*oldlenp < sizeof(nchstats)) {
+ if (*oldlenp < sizeof(stats)) {
*oldlenp = 0;
return 0;
}
+ /*
+ * Take this CPU's per-cpu lock to hold off cache_reclaim()
+ * from doing a stats update while doing minimal damage to
+ * concurrent operations.
+ */
sysctl_unlock();
- mutex_enter(&namecache_lock);
+ my_cpup = curcpu()->ci_data.cpu_nch;
+ mutex_enter(&my_cpup->cpu_lock);
+ stats = nchstats;
+#ifdef CACHE_STATS_CURRENT
for (CPU_INFO_FOREACH(cii, ci)) {
struct nchcpu *cpup = ci->ci_data.cpu_nch;
- UPDATE(cpup, ncs_goodhits);
- UPDATE(cpup, ncs_neghits);
- UPDATE(cpup, ncs_badhits);
- UPDATE(cpup, ncs_falsehits);
- UPDATE(cpup, ncs_miss);
-
- UPDATE(cpup, ncs_pass2);
- UPDATE(cpup, ncs_2passes);
- UPDATE(cpup, ncs_revhits);
- UPDATE(cpup, ncs_revmiss);
+ ADD(stats, cpup, ncs_goodhits);
+ ADD(stats, cpup, ncs_neghits);
+ ADD(stats, cpup, ncs_badhits);
+ ADD(stats, cpup, ncs_falsehits);
+ ADD(stats, cpup, ncs_miss);
+ ADD(stats, cpup, ncs_long);
+ ADD(stats, cpup, ncs_pass2);
+ ADD(stats, cpup, ncs_2passes);
+ ADD(stats, cpup, ncs_revhits);
+ ADD(stats, cpup, ncs_revmiss);
}
- mutex_exit(&namecache_lock);
+#endif /* CACHE_STATS_CURRENT */
+ mutex_exit(&my_cpup->cpu_lock);
sysctl_relock();
- *oldlenp = sizeof(nchstats);
- return sysctl_copyout(l, &nchstats, oldp, sizeof(nchstats));
+ *oldlenp = sizeof(stats);
+ return sysctl_copyout(l, &stats, oldp, sizeof(stats));
}
static void
Index: src/sys/sys/namei.src
diff -u src/sys/sys/namei.src:1.45 src/sys/sys/namei.src:1.46
--- src/sys/sys/namei.src:1.45 Sun Dec 1 13:45:42 2019
+++ src/sys/sys/namei.src Sun Dec 1 18:31:19 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: namei.src,v 1.45 2019/12/01 13:45:42 ad Exp $ */
+/* $NetBSD: namei.src,v 1.46 2019/12/01 18:31:19 ad Exp $ */
/*
* Copyright (c) 1985, 1989, 1991, 1993
@@ -203,7 +203,6 @@ NAMEIFL PARAMASK 0x02ee300 /* mask of pa
*
* - stable after initialization
* L namecache_lock
- * G namecache_gc_lock
* C struct nchcpu::cpu_lock
* L/C insert needs L, read needs L or any C,
* must hold L and all C after (or during) delete before free
@@ -215,11 +214,11 @@ struct namecache {
TAILQ_ENTRY(namecache) nc_lru; /* L pseudo-lru chain */
LIST_ENTRY(namecache) nc_dvlist;/* L dvp's list of cache entries */
LIST_ENTRY(namecache) nc_vlist; /* L vp's list of cache entries */
- SLIST_ENTRY(namecache) nc_gclist;/*G queue for garbage collection */
struct vnode *nc_dvp; /* N vnode of parent of name */
struct vnode *nc_vp; /* N vnode the name refers to */
- kmutex_t *nc_lock; /* - lock on this entry */
- volatile int nc_hittime; /* N last time scored a hit */
+ void *nc_gcqueue; /* N queue for garbage collection */
+ kmutex_t nc_lock; /* lock on this entry */
+ int nc_hittime; /* N last time scored a hit */
int nc_flags; /* - copy of componentname ISWHITEOUT */
u_short nc_nlen; /* - length of name */
char nc_name[0]; /* - segment name */
