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From: Trond Myklebust <trondmy@gmail.com>
To: "J . Bruce Fields" <bfields@fieldses.org>
Cc: linux-nfs@vger.kernel.org
Subject: [PATCH 13/15] knfsd: Simplify NFS duplicate replay cache
Date: Mon,  1 Oct 2018 10:41:55 -0400	[thread overview]
Message-ID: <20181001144157.3515-14-trond.myklebust@hammerspace.com> (raw)
In-Reply-To: <20181001144157.3515-13-trond.myklebust@hammerspace.com>

Simplify the duplicate replay cache by initialising the preallocated
cache entry, so that we can use it as a key for the cache lookup.

Note that the 99.999% case we want to optimise for is still the one
where the lookup fails, and we have to add this entry to the cache,
so preinitialising should not cause a performance penalty.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfsd/cache.h    |  6 +--
 fs/nfsd/nfscache.c | 94 ++++++++++++++++++++++------------------------
 2 files changed, 47 insertions(+), 53 deletions(-)

diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h
index b7559c6f2b97..bd77d5f6fe53 100644
--- a/fs/nfsd/cache.h
+++ b/fs/nfsd/cache.h
@@ -24,13 +24,13 @@ struct svc_cacherep {
 	unsigned char		c_state,	/* unused, inprog, done */
 				c_type,		/* status, buffer */
 				c_secure : 1;	/* req came from port < 1024 */
-	struct sockaddr_in6	c_addr;
 	__be32			c_xid;
-	u32			c_prot;
+	__wsum			c_csum;
 	u32			c_proc;
+	u32			c_prot;
 	u32			c_vers;
 	unsigned int		c_len;
-	__wsum			c_csum;
+	struct sockaddr_in6	c_addr;
 	unsigned long		c_timestamp;
 	union {
 		struct kvec	u_vec;
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index cef4686f87ef..527ce4c65765 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -121,7 +121,7 @@ nfsd_cache_hash(__be32 xid)
 }
 
 static struct svc_cacherep *
-nfsd_reply_cache_alloc(void)
+nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum)
 {
 	struct svc_cacherep	*rp;
 
@@ -130,6 +130,16 @@ nfsd_reply_cache_alloc(void)
 		rp->c_state = RC_UNUSED;
 		rp->c_type = RC_NOCACHE;
 		INIT_LIST_HEAD(&rp->c_lru);
+
+		rp->c_xid = rqstp->rq_xid;
+		rp->c_proc = rqstp->rq_proc;
+		memset(&rp->c_addr, 0, sizeof(rp->c_addr));
+		rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp));
+		rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp)));
+		rp->c_prot = rqstp->rq_prot;
+		rp->c_vers = rqstp->rq_vers;
+		rp->c_len = rqstp->rq_arg.len;
+		rp->c_csum = csum;
 	}
 	return rp;
 }
@@ -141,9 +151,11 @@ nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
 		drc_mem_usage -= rp->c_replvec.iov_len;
 		kfree(rp->c_replvec.iov_base);
 	}
-	list_del(&rp->c_lru);
-	atomic_dec(&num_drc_entries);
-	drc_mem_usage -= sizeof(*rp);
+	if (rp->c_state != RC_UNUSED) {
+		list_del(&rp->c_lru);
+		atomic_dec(&num_drc_entries);
+		drc_mem_usage -= sizeof(*rp);
+	}
 	kmem_cache_free(drc_slab, rp);
 }
 
@@ -319,24 +331,23 @@ nfsd_cache_csum(struct svc_rqst *rqstp)
 }
 
 static bool
-nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp)
+nfsd_cache_match(const struct svc_cacherep *key, const struct svc_cacherep *rp)
 {
 	/* Check RPC XID first */
-	if (rqstp->rq_xid != rp->c_xid)
+	if (key->c_xid != rp->c_xid)
 		return false;
 	/* compare checksum of NFS data */
-	if (csum != rp->c_csum) {
+	if (key->c_csum != rp->c_csum) {
 		++payload_misses;
 		return false;
 	}
 
 	/* Other discriminators */
-	if (rqstp->rq_proc != rp->c_proc ||
-	    rqstp->rq_prot != rp->c_prot ||
-	    rqstp->rq_vers != rp->c_vers ||
-	    rqstp->rq_arg.len != rp->c_len ||
-	    !rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) ||
-	    rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr))
+	if (key->c_proc != rp->c_proc ||
+	    key->c_prot != rp->c_prot ||
+	    key->c_vers != rp->c_vers ||
+	    key->c_len != rp->c_len ||
+	    memcmp(&key->c_addr, &rp->c_addr, sizeof(key->c_addr)) != 0)
 		return false;
 
 	return true;
@@ -345,19 +356,18 @@ nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp)
 /*
  * Search the request hash for an entry that matches the given rqstp.
  * Must be called with cache_lock held. Returns the found entry or
- * NULL on failure.
+ * inserts an empty key on failure.
  */
 static struct svc_cacherep *
-nfsd_cache_search(struct nfsd_drc_bucket *b, struct svc_rqst *rqstp,
-		__wsum csum)
+nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key)
 {
-	struct svc_cacherep	*rp, *ret = NULL;
+	struct svc_cacherep	*rp, *ret = key;
 	struct list_head 	*rh = &b->lru_head;
 	unsigned int		entries = 0;
 
 	list_for_each_entry(rp, rh, c_lru) {
 		++entries;
-		if (nfsd_cache_match(rqstp, csum, rp)) {
+		if (nfsd_cache_match(key, rp)) {
 			ret = rp;
 			break;
 		}
@@ -374,6 +384,7 @@ nfsd_cache_search(struct nfsd_drc_bucket *b, struct svc_rqst *rqstp,
 				atomic_read(&num_drc_entries));
 	}
 
+	lru_put_end(b, ret);
 	return ret;
 }
 
@@ -389,9 +400,6 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
 {
 	struct svc_cacherep	*rp, *found;
 	__be32			xid = rqstp->rq_xid;
-	u32			proto =  rqstp->rq_prot,
-				vers = rqstp->rq_vers,
-				proc = rqstp->rq_proc;
 	__wsum			csum;
 	u32 hash = nfsd_cache_hash(xid);
 	struct nfsd_drc_bucket *b = &drc_hashtbl[hash];
@@ -410,52 +418,38 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
 	 * Since the common case is a cache miss followed by an insert,
 	 * preallocate an entry.
 	 */
-	rp = nfsd_reply_cache_alloc();
-	spin_lock(&b->cache_lock);
-	if (likely(rp)) {
-		atomic_inc(&num_drc_entries);
-		drc_mem_usage += sizeof(*rp);
+	rp = nfsd_reply_cache_alloc(rqstp, csum);
+	if (!rp) {
+		dprintk("nfsd: unable to allocate DRC entry!\n");
+		return rtn;
 	}
 
-	/* go ahead and prune the cache */
-	prune_bucket(b);
-
-	found = nfsd_cache_search(b, rqstp, csum);
-	if (found) {
-		if (likely(rp))
-			nfsd_reply_cache_free_locked(rp);
+	spin_lock(&b->cache_lock);
+	found = nfsd_cache_insert(b, rp);
+	if (found != rp) {
+		nfsd_reply_cache_free_locked(rp);
 		rp = found;
 		goto found_entry;
 	}
 
-	if (!rp) {
-		dprintk("nfsd: unable to allocate DRC entry!\n");
-		goto out;
-	}
-
 	nfsdstats.rcmisses++;
 	rqstp->rq_cacherep = rp;
 	rp->c_state = RC_INPROG;
-	rp->c_xid = xid;
-	rp->c_proc = proc;
-	rpc_copy_addr((struct sockaddr *)&rp->c_addr, svc_addr(rqstp));
-	rpc_set_port((struct sockaddr *)&rp->c_addr, rpc_get_port(svc_addr(rqstp)));
-	rp->c_prot = proto;
-	rp->c_vers = vers;
-	rp->c_len = rqstp->rq_arg.len;
-	rp->c_csum = csum;
 
-	lru_put_end(b, rp);
+	atomic_inc(&num_drc_entries);
+	drc_mem_usage += sizeof(*rp);
+
+	/* go ahead and prune the cache */
+	prune_bucket(b);
  out:
 	spin_unlock(&b->cache_lock);
 	return rtn;
 
 found_entry:
-	nfsdstats.rchits++;
 	/* We found a matching entry which is either in progress or done. */
-	lru_put_end(b, rp);
-
+	nfsdstats.rchits++;
 	rtn = RC_DROPIT;
+
 	/* Request being processed */
 	if (rp->c_state == RC_INPROG)
 		goto out;
-- 
2.17.1

  reply	other threads:[~2018-10-01 21:20 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-01 14:41 [PATCH 00/15] Performance improvements for knfsd Trond Myklebust
2018-10-01 14:41 ` [PATCH 01/15] SUNRPC: Remove the server 'authtab_lock' and just use RCU Trond Myklebust
2018-10-01 14:41   ` [PATCH 02/15] SUNRPC: Add lockless lookup of the server's auth domain Trond Myklebust
2018-10-01 14:41     ` [PATCH 03/15] SUNRPC: Allow cache lookups to use RCU protection rather than the r/w spinlock Trond Myklebust
2018-10-01 14:41       ` [PATCH 04/15] SUNRPC: Make server side AUTH_UNIX use lockless lookups Trond Myklebust
2018-10-01 14:41         ` [PATCH 05/15] knfsd: Allow lockless lookups of the exports Trond Myklebust
2018-10-01 14:41           ` [PATCH 06/15] SUNRPC: Lockless server RPCSEC_GSS context lookup Trond Myklebust
2018-10-01 14:41             ` [PATCH 07/15] knfsd: Lockless lookup of NFSv4 identities Trond Myklebust
2018-10-01 14:41               ` [PATCH 08/15] NFS: Lockless DNS lookups Trond Myklebust
2018-10-01 14:41                 ` [PATCH 09/15] SUNRPC: Remove non-RCU protected lookup Trond Myklebust
2018-10-01 14:41                   ` [PATCH 10/15] SUNRPC: Replace the cache_detail->hash_lock with a regular spinlock Trond Myklebust
2018-10-01 14:41                     ` [PATCH 11/15] SUNRPC: Simplify TCP receive code Trond Myklebust
2018-10-01 14:41                       ` [PATCH 12/15] knfsd: Remove dead code from nfsd_cache_lookup Trond Myklebust
2018-10-01 14:41                         ` Trond Myklebust [this message]
2018-10-01 14:41                           ` [PATCH 14/15] knfsd: Further simplify the cache lookup Trond Myklebust
2018-10-01 14:41                             ` [PATCH 15/15] knfsd: Improve lookup performance in the duplicate reply cache using an rbtree Trond Myklebust
2018-10-04  0:44                               ` J . Bruce Fields
2018-10-03 17:14                           ` [PATCH 13/15] knfsd: Simplify NFS duplicate replay cache J . Bruce Fields
2018-10-03 18:01                             ` Trond Myklebust
2018-10-03 18:11                               ` bfields
2018-10-03 23:51                                 ` bfields
2018-10-03 16:10                 ` [PATCH 08/15] NFS: Lockless DNS lookups J . Bruce Fields
2018-10-03 17:55                   ` Trond Myklebust
2018-10-03 16:08       ` [PATCH 03/15] SUNRPC: Allow cache lookups to use RCU protection rather than the r/w spinlock J . Bruce Fields
2018-10-02 19:39   ` [PATCH 01/15] SUNRPC: Remove the server 'authtab_lock' and just use RCU J . Bruce Fields
2018-10-01 15:29 ` [PATCH 00/15] Performance improvements for knfsd Trond Myklebust

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