Commit 736c6625 authored by Trond Myklebust's avatar Trond Myklebust Committed by J. Bruce Fields
Browse files

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: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent ed00c2f6

fs/nfsd/cache.h

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ struct svc_cacherep { 
		struct sockaddr_in6	k_addr;

	} c_key;



	struct rb_node		c_node;

	struct list_head	c_lru;

	unsigned char		c_state,	/* unused, inprog, done */

				c_type,		/* status, buffer */

fs/nfsd/nfscache.c

+26 −11
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#define TARGET_BUCKET_SIZE	64



struct nfsd_drc_bucket {

	struct rb_root rb_head;

	struct list_head lru_head;

	spinlock_t cache_lock;

};
@@ -129,6 +130,7 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum) 
	if (rp) {

		rp->c_state = RC_UNUSED;

		rp->c_type = RC_NOCACHE;

		RB_CLEAR_NODE(&rp->c_node);

		INIT_LIST_HEAD(&rp->c_lru);



		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

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) {

		drc_mem_usage -= rp->c_replvec.iov_len;

		kfree(rp->c_replvec.iov_base);

	}

	if (rp->c_state != RC_UNUSED) {

		rb_erase(&rp->c_node, &b->rb_head);

		list_del(&rp->c_lru);

		atomic_dec(&num_drc_entries);

		drc_mem_usage -= sizeof(*rp);
@@ -163,7 +166,7 @@ static void 
nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)

{

	spin_lock(&b->cache_lock);

	nfsd_reply_cache_free_locked(rp);

	nfsd_reply_cache_free_locked(b, rp);

	spin_unlock(&b->cache_lock);

}
@@ -219,7 +222,7 @@ void nfsd_reply_cache_shutdown(void) 
		struct list_head *head = &drc_hashtbl[i].lru_head;

		while (!list_empty(head)) {

			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 &&

		    time_before(jiffies, rp->c_timestamp + RC_EXPIRE))

			break;

		nfsd_reply_cache_free_locked(rp);

		nfsd_reply_cache_free_locked(b, rp);

		freed++;

	}

	return freed;
@@ -349,17 +352,29 @@ static struct svc_cacherep * 
nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *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;

	int cmp;



	list_for_each_entry(rp, rh, c_lru) {

	while (*p != NULL) {

		++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;

			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 */

	if (entries > longest_chain) {

		longest_chain = entries;
@@ -414,7 +429,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) 
	spin_lock(&b->cache_lock);

	found = nfsd_cache_insert(b, rp);

	if (found != rp) {

		nfsd_reply_cache_free_locked(rp);

		nfsd_reply_cache_free_locked(NULL, rp);

		rp = found;

		goto found_entry;

	}
@@ -462,7 +477,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) 
		break;

	default:

		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;