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knfsd: Improve lookup performance in the duplicate reply cache using an rbtree
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>
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parent
ed00c2f652
commit
736c6625de
fs/nfsd
@ -30,6 +30,7 @@ struct svc_cacherep {
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struct sockaddr_in6 k_addr;
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} c_key;
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struct rb_node c_node;
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struct list_head c_lru;
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unsigned char c_state, /* unused, inprog, done */
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c_type, /* status, buffer */
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@ -30,6 +30,7 @@
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#define TARGET_BUCKET_SIZE 64
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struct nfsd_drc_bucket {
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struct rb_root rb_head;
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struct list_head lru_head;
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spinlock_t cache_lock;
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};
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@ -129,6 +130,7 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum)
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if (rp) {
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rp->c_state = RC_UNUSED;
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rp->c_type = RC_NOCACHE;
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RB_CLEAR_NODE(&rp->c_node);
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INIT_LIST_HEAD(&rp->c_lru);
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memset(&rp->c_key, 0, sizeof(rp->c_key));
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@ -145,13 +147,14 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum)
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}
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static void
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nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
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nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
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{
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if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
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drc_mem_usage -= rp->c_replvec.iov_len;
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kfree(rp->c_replvec.iov_base);
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}
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if (rp->c_state != RC_UNUSED) {
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rb_erase(&rp->c_node, &b->rb_head);
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list_del(&rp->c_lru);
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atomic_dec(&num_drc_entries);
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drc_mem_usage -= sizeof(*rp);
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@ -163,7 +166,7 @@ static void
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nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
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{
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spin_lock(&b->cache_lock);
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nfsd_reply_cache_free_locked(rp);
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nfsd_reply_cache_free_locked(b, rp);
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spin_unlock(&b->cache_lock);
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}
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@ -219,7 +222,7 @@ void nfsd_reply_cache_shutdown(void)
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struct list_head *head = &drc_hashtbl[i].lru_head;
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while (!list_empty(head)) {
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rp = list_first_entry(head, struct svc_cacherep, c_lru);
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nfsd_reply_cache_free_locked(rp);
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nfsd_reply_cache_free_locked(&drc_hashtbl[i], rp);
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}
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}
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@ -258,7 +261,7 @@ prune_bucket(struct nfsd_drc_bucket *b)
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if (atomic_read(&num_drc_entries) <= max_drc_entries &&
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time_before(jiffies, rp->c_timestamp + RC_EXPIRE))
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break;
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nfsd_reply_cache_free_locked(rp);
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nfsd_reply_cache_free_locked(b, rp);
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freed++;
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}
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return freed;
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@ -349,17 +352,29 @@ static struct svc_cacherep *
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nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key)
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{
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struct svc_cacherep *rp, *ret = key;
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struct list_head *rh = &b->lru_head;
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struct rb_node **p = &b->rb_head.rb_node,
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*parent = NULL;
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unsigned int entries = 0;
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int cmp;
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list_for_each_entry(rp, rh, c_lru) {
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while (*p != NULL) {
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++entries;
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if (nfsd_cache_key_cmp(key, rp) == 0) {
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parent = *p;
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rp = rb_entry(parent, struct svc_cacherep, c_node);
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cmp = nfsd_cache_key_cmp(key, rp);
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if (cmp < 0)
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p = &parent->rb_left;
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else if (cmp > 0)
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p = &parent->rb_right;
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else {
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ret = rp;
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break;
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goto out;
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}
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}
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rb_link_node(&key->c_node, parent, p);
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rb_insert_color(&key->c_node, &b->rb_head);
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out:
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/* tally hash chain length stats */
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if (entries > longest_chain) {
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longest_chain = entries;
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@ -414,7 +429,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
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spin_lock(&b->cache_lock);
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found = nfsd_cache_insert(b, rp);
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if (found != rp) {
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nfsd_reply_cache_free_locked(rp);
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nfsd_reply_cache_free_locked(NULL, rp);
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rp = found;
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goto found_entry;
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}
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@ -462,7 +477,7 @@ found_entry:
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break;
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default:
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printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
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nfsd_reply_cache_free_locked(rp);
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nfsd_reply_cache_free_locked(b, rp);
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}
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goto out;
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