[PATCH] knfsd: move tempsock aging to a timer

Following are 11 patches from Greg Banks which combine to make knfsd more
Numa-aware.  They reduce hitting on 'global' data structures, and create some
data-structures that can be node-local.

knfsd threads are bound to a particular node, and the thread to handle a new
request is chosen from the threads that are attach to the node that received
the interrupt.

The distribution of threads across nodes can be controlled by a new file in
the 'nfsd' filesystem, though the default approach of an even spread is
probably fine for most sites.

Some (old) numbers that show the efficacy of these patches: N == number of
NICs == number of CPUs == nmber of clients.  Number of NUMA nodes == N/2

N	Throughput, MiB/s	CPU usage, % (max=N*100)
	Before	After		Before	After
	---	------	----		-----	-----
	4	312	435		350	228
	6	500	656		501	418
	8	562	804		690	589

This patch:

Move the aging of RPC/TCP connection sockets from the main svc_recv() loop to
a timer which uses a mark-and-sweep algorithm every 6 minutes.  This reduces
the amount of work that needs to be done in the main RPC loop and the length
of time we need to hold the (effectively global) svc_serv->sv_lock.

[akpm@osdl.org: cleanup]
Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 70 insertions, 26 deletions

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index bc9bd189a540..9ba1a071ff06 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -74,6 +74,13 @@ static struct svc_deferred_req *svc_deferred_dequeue(struct svc_sock *svsk);
 static int svc_deferred_recv(struct svc_rqst *rqstp);
 static struct cache_deferred_req *svc_defer(struct cache_req *req);
 
+/* apparently the "standard" is that clients close
+ * idle connections after 5 minutes, servers after
+ * 6 minutes
+ *   http://www.connectathon.org/talks96/nfstcp.pdf
+ */
+static int svc_conn_age_period = 6*60;
+
 /*
  * Queue up an idle server thread.  Must have serv->sv_lock held.
  * Note: this is really a stack rather than a queue, so that we only
@@ -1220,24 +1227,7 @@ svc_recv(struct svc_rqst *rqstp, long timeout)
                 return -EINTR;
 
         spin_lock_bh(&serv->sv_lock);
-        if (!list_empty(&serv->sv_tempsocks)) {
-                svsk = list_entry(serv->sv_tempsocks.next,
-                                  struct svc_sock, sk_list);
-                /* apparently the "standard" is that clients close
-                 * idle connections after 5 minutes, servers after
-                 * 6 minutes
-                 *   http://www.connectathon.org/talks96/nfstcp.pdf 
-                 */
-                if (get_seconds() - svsk->sk_lastrecv < 6*60
-                    || test_bit(SK_BUSY, &svsk->sk_flags))
-                        svsk = NULL;
-        }
-        if (svsk) {
-                set_bit(SK_BUSY, &svsk->sk_flags);
-                set_bit(SK_CLOSE, &svsk->sk_flags);
-                rqstp->rq_sock = svsk;
-                svsk->sk_inuse++;
-        } else if ((svsk = svc_sock_dequeue(serv)) != NULL) {
+        if ((svsk = svc_sock_dequeue(serv)) != NULL) {
                 rqstp->rq_sock = svsk;
                 svsk->sk_inuse++;
                 rqstp->rq_reserved = serv->sv_bufsz;    
@@ -1282,13 +1272,7 @@ svc_recv(struct svc_rqst *rqstp, long timeout)
                 return -EAGAIN;
         }
         svsk->sk_lastrecv = get_seconds();
-        if (test_bit(SK_TEMP, &svsk->sk_flags)) {
-                /* push active sockets to end of list */
-                spin_lock_bh(&serv->sv_lock);
-                if (!list_empty(&svsk->sk_list))
-                        list_move_tail(&svsk->sk_list, &serv->sv_tempsocks);
-                spin_unlock_bh(&serv->sv_lock);
-        }
+        clear_bit(SK_OLD, &svsk->sk_flags);
 
         rqstp->rq_secure  = ntohs(rqstp->rq_addr.sin_port) < 1024;
         rqstp->rq_chandle.defer = svc_defer;
@@ -1348,6 +1332,58 @@ svc_send(struct svc_rqst *rqstp)
 }
 
 /*
+ * Timer function to close old temporary sockets, using
+ * a mark-and-sweep algorithm.
+ */
+static void
+svc_age_temp_sockets(unsigned long closure)
+{
+        struct svc_serv *serv = (struct svc_serv *)closure;
+        struct svc_sock *svsk;
+        struct list_head *le, *next;
+        LIST_HEAD(to_be_aged);
+
+        dprintk("svc_age_temp_sockets\n");
+
+        if (!spin_trylock_bh(&serv->sv_lock)) {
+                /* busy, try again 1 sec later */
+                dprintk("svc_age_temp_sockets: busy\n");
+                mod_timer(&serv->sv_temptimer, jiffies + HZ);
+                return;
+        }
+
+        list_for_each_safe(le, next, &serv->sv_tempsocks) {
+                svsk = list_entry(le, struct svc_sock, sk_list);
+
+                if (!test_and_set_bit(SK_OLD, &svsk->sk_flags))
+                        continue;
+                if (svsk->sk_inuse || test_bit(SK_BUSY, &svsk->sk_flags))
+                        continue;
+                svsk->sk_inuse++;
+                list_move(le, &to_be_aged);
+                set_bit(SK_CLOSE, &svsk->sk_flags);
+                set_bit(SK_DETACHED, &svsk->sk_flags);
+        }
+        spin_unlock_bh(&serv->sv_lock);
+
+        while (!list_empty(&to_be_aged)) {
+                le = to_be_aged.next;
+                /* fiddling the sk_list node is safe 'cos we're SK_DETACHED */
+                list_del_init(le);
+                svsk = list_entry(le, struct svc_sock, sk_list);
+
+                dprintk("queuing svsk %p for closing, %lu seconds old\n",
+                        svsk, get_seconds() - svsk->sk_lastrecv);
+
+                /* a thread will dequeue and close it soon */
+                svc_sock_enqueue(svsk);
+                svc_sock_put(svsk);
+        }
+
+        mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);
+}
+
+/*
  * Initialize socket for RPC use and create svc_sock struct
  * XXX: May want to setsockopt SO_SNDBUF and SO_RCVBUF.
  */
@@ -1400,6 +1436,13 @@ svc_setup_socket(struct svc_serv *serv, struct socket *sock,
                 set_bit(SK_TEMP, &svsk->sk_flags);
                 list_add(&svsk->sk_list, &serv->sv_tempsocks);
                 serv->sv_tmpcnt++;
+                if (serv->sv_temptimer.function == NULL) {
+                        /* setup timer to age temp sockets */
+                        setup_timer(&serv->sv_temptimer, svc_age_temp_sockets,
+                                        (unsigned long)serv);
+                        mod_timer(&serv->sv_temptimer,
+                                        jiffies + svc_conn_age_period * HZ);
+                }
         } else {
                 clear_bit(SK_TEMP, &svsk->sk_flags);
                 list_add(&svsk->sk_list, &serv->sv_permsocks);
@@ -1513,7 +1556,8 @@ svc_delete_socket(struct svc_sock *svsk)
 
         spin_lock_bh(&serv->sv_lock);
 
-        list_del_init(&svsk->sk_list);
+        if (!test_and_set_bit(SK_DETACHED, &svsk->sk_flags))
+                list_del_init(&svsk->sk_list);
         list_del_init(&svsk->sk_ready);
         if (!test_and_set_bit(SK_DEAD, &svsk->sk_flags))
                 if (test_bit(SK_TEMP, &svsk->sk_flags))