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knfsd: Improve lookup performance in the duplicate reply cache using an rbtree

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Use an rbtree to ensure the lookup/insert of an entry in a DRC bucket is
O(log(N)).

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Trond Myklebust 2018-10-01 10:41:57 -04:00 committed by J. Bruce Fields
parent ed00c2f652
commit 736c6625de
2 changed files with 27 additions and 11 deletions
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1
fs/nfsd/cache.h
View File

@ -30,6 +30,7 @@ struct svc_cacherep {
struct sockaddr_in6 k_addr; struct sockaddr_in6 k_addr;
} c_key; } c_key;
struct rb_node c_node;
struct list_head c_lru; struct list_head c_lru;
unsigned char c_state, /* unused, inprog, done */ unsigned char c_state, /* unused, inprog, done */
c_type, /* status, buffer */ c_type, /* status, buffer */

37
fs/nfsd/nfscache.c
View File

@ -30,6 +30,7 @@
#define TARGET_BUCKET_SIZE 64 #define TARGET_BUCKET_SIZE 64
struct nfsd_drc_bucket { struct nfsd_drc_bucket {
struct rb_root rb_head;
struct list_head lru_head; struct list_head lru_head;
spinlock_t cache_lock; spinlock_t cache_lock;
}; };
@ -129,6 +130,7 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum)
if (rp) { if (rp) {
rp->c_state = RC_UNUSED; rp->c_state = RC_UNUSED;
rp->c_type = RC_NOCACHE; rp->c_type = RC_NOCACHE;
RB_CLEAR_NODE(&rp->c_node);
INIT_LIST_HEAD(&rp->c_lru); INIT_LIST_HEAD(&rp->c_lru);
memset(&rp->c_key, 0, sizeof(rp->c_key)); memset(&rp->c_key, 0, sizeof(rp->c_key));
@ -145,13 +147,14 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum)
} }
static void static void
nfsd_reply_cache_free_locked(struct svc_cacherep *rp) nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
{ {
if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) { if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
drc_mem_usage -= rp->c_replvec.iov_len; drc_mem_usage -= rp->c_replvec.iov_len;
kfree(rp->c_replvec.iov_base); kfree(rp->c_replvec.iov_base);
} }
if (rp->c_state != RC_UNUSED) { if (rp->c_state != RC_UNUSED) {
rb_erase(&rp->c_node, &b->rb_head);
list_del(&rp->c_lru); list_del(&rp->c_lru);
atomic_dec(&num_drc_entries); atomic_dec(&num_drc_entries);
drc_mem_usage -= sizeof(*rp); drc_mem_usage -= sizeof(*rp);
@ -163,7 +166,7 @@ static void
nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp) nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
{ {
spin_lock(&b->cache_lock); spin_lock(&b->cache_lock);
nfsd_reply_cache_free_locked(rp); nfsd_reply_cache_free_locked(b, rp);
spin_unlock(&b->cache_lock); spin_unlock(&b->cache_lock);
} }
@ -219,7 +222,7 @@ void nfsd_reply_cache_shutdown(void)
struct list_head *head = &drc_hashtbl[i].lru_head; struct list_head *head = &drc_hashtbl[i].lru_head;
while (!list_empty(head)) { while (!list_empty(head)) {
rp = list_first_entry(head, struct svc_cacherep, c_lru); rp = list_first_entry(head, struct svc_cacherep, c_lru);
nfsd_reply_cache_free_locked(rp); nfsd_reply_cache_free_locked(&drc_hashtbl[i], rp);
} }
} }
@ -258,7 +261,7 @@ prune_bucket(struct nfsd_drc_bucket *b)
if (atomic_read(&num_drc_entries) <= max_drc_entries && if (atomic_read(&num_drc_entries) <= max_drc_entries &&
time_before(jiffies, rp->c_timestamp + RC_EXPIRE)) time_before(jiffies, rp->c_timestamp + RC_EXPIRE))
break; break;
nfsd_reply_cache_free_locked(rp); nfsd_reply_cache_free_locked(b, rp);
freed++; freed++;
} }
return freed; return freed;
@ -349,17 +352,29 @@ static struct svc_cacherep *
nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key) nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key)
{ {
struct svc_cacherep *rp, *ret = key; struct svc_cacherep *rp, *ret = key;
struct list_head *rh = &b->lru_head; struct rb_node **p = &b->rb_head.rb_node,
*parent = NULL;
unsigned int entries = 0; unsigned int entries = 0;
int cmp;
list_for_each_entry(rp, rh, c_lru) { while (*p != NULL) {
++entries; ++entries;
if (nfsd_cache_key_cmp(key, rp) == 0) { parent = *p;
rp = rb_entry(parent, struct svc_cacherep, c_node);
cmp = nfsd_cache_key_cmp(key, rp);
if (cmp < 0)
p = &parent->rb_left;
else if (cmp > 0)
p = &parent->rb_right;
else {
ret = rp; ret = rp;
break; goto out;
} }
} }
rb_link_node(&key->c_node, parent, p);
rb_insert_color(&key->c_node, &b->rb_head);
out:
/* tally hash chain length stats */ /* tally hash chain length stats */
if (entries > longest_chain) { if (entries > longest_chain) {
longest_chain = entries; longest_chain = entries;
@ -414,7 +429,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
spin_lock(&b->cache_lock); spin_lock(&b->cache_lock);
found = nfsd_cache_insert(b, rp); found = nfsd_cache_insert(b, rp);
if (found != rp) { if (found != rp) {
nfsd_reply_cache_free_locked(rp); nfsd_reply_cache_free_locked(NULL, rp);
rp = found; rp = found;
goto found_entry; goto found_entry;
} }
@ -462,7 +477,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
break; break;
default: default:
printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type); printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
nfsd_reply_cache_free_locked(rp); nfsd_reply_cache_free_locked(b, rp);
} }
goto out; goto out;