Revert "net: sctp: Fix a_rwnd/rwnd management to reflect real state o…

…f the receiver's buffer" [ Upstream commit 362d520 ] This reverts commit ef2820a ("net: sctp: Fix a_rwnd/rwnd management to reflect real state of the receiver's buffer") as it introduced a serious performance regression on SCTP over IPv4 and IPv6, though a not as dramatic on the latter. Measurements are on 10Gbit/s with ixgbe NICs. Current state: [root@Lab200slot2 ~]# iperf3 --sctp -4 -c 192.168.241.3 -V -l 1452 -t 60 iperf version 3.0.1 (10 January 2014) Linux Lab200slot2 3.14.0 #1 SMP Thu Apr 3 23:18:29 EDT 2014 x86_64 Time: Fri, 11 Apr 2014 17:56:21 GMT Connecting to host 192.168.241.3, port 5201 Cookie: Lab200slot2.1397238981.812898.548918 [ 4] local 192.168.241.2 port 38616 connected to 192.168.241.3 port 5201 Starting Test: protocol: SCTP, 1 streams, 1452 byte blocks, omitting 0 seconds, 60 second test [ ID] Interval Transfer Bandwidth [ 4] 0.00-1.09 sec 20.8 MBytes 161 Mbits/sec [ 4] 1.09-2.13 sec 10.8 MBytes 86.8 Mbits/sec [ 4] 2.13-3.15 sec 3.57 MBytes 29.5 Mbits/sec [ 4] 3.15-4.16 sec 4.33 MBytes 35.7 Mbits/sec [ 4] 4.16-6.21 sec 10.4 MBytes 42.7 Mbits/sec [ 4] 6.21-6.21 sec 0.00 Bytes 0.00 bits/sec [ 4] 6.21-7.35 sec 34.6 MBytes 253 Mbits/sec [ 4] 7.35-11.45 sec 22.0 MBytes 45.0 Mbits/sec [ 4] 11.45-11.45 sec 0.00 Bytes 0.00 bits/sec [ 4] 11.45-11.45 sec 0.00 Bytes 0.00 bits/sec [ 4] 11.45-11.45 sec 0.00 Bytes 0.00 bits/sec [ 4] 11.45-12.51 sec 16.0 MBytes 126 Mbits/sec [ 4] 12.51-13.59 sec 20.3 MBytes 158 Mbits/sec [ 4] 13.59-14.65 sec 13.4 MBytes 107 Mbits/sec [ 4] 14.65-16.79 sec 33.3 MBytes 130 Mbits/sec [ 4] 16.79-16.79 sec 0.00 Bytes 0.00 bits/sec [ 4] 16.79-17.82 sec 5.94 MBytes 48.7 Mbits/sec (etc) [root@Lab200slot2 ~]# iperf3 --sctp -6 -c 2001:db8:0:f101::1 -V -l 1400 -t 60 iperf version 3.0.1 (10 January 2014) Linux Lab200slot2 3.14.0 #1 SMP Thu Apr 3 23:18:29 EDT 2014 x86_64 Time: Fri, 11 Apr 2014 19:08:41 GMT Connecting to host 2001:db8:0:f101::1, port 5201 Cookie: Lab200slot2.1397243321.714295.2b3f7c [ 4] local 2001:db8:0:f101::2 port 55804 connected to 2001:db8:0:f101::1 port 5201 Starting Test: protocol: SCTP, 1 streams, 1400 byte blocks, omitting 0 seconds, 60 second test [ ID] Interval Transfer Bandwidth [ 4] 0.00-1.00 sec 169 MBytes 1.42 Gbits/sec [ 4] 1.00-2.00 sec 201 MBytes 1.69 Gbits/sec [ 4] 2.00-3.00 sec 188 MBytes 1.58 Gbits/sec [ 4] 3.00-4.00 sec 174 MBytes 1.46 Gbits/sec [ 4] 4.00-5.00 sec 165 MBytes 1.39 Gbits/sec [ 4] 5.00-6.00 sec 199 MBytes 1.67 Gbits/sec [ 4] 6.00-7.00 sec 163 MBytes 1.36 Gbits/sec [ 4] 7.00-8.00 sec 174 MBytes 1.46 Gbits/sec [ 4] 8.00-9.00 sec 193 MBytes 1.62 Gbits/sec [ 4] 9.00-10.00 sec 196 MBytes 1.65 Gbits/sec [ 4] 10.00-11.00 sec 157 MBytes 1.31 Gbits/sec [ 4] 11.00-12.00 sec 175 MBytes 1.47 Gbits/sec [ 4] 12.00-13.00 sec 192 MBytes 1.61 Gbits/sec [ 4] 13.00-14.00 sec 199 MBytes 1.67 Gbits/sec (etc) After patch: [root@Lab200slot2 ~]# iperf3 --sctp -4 -c 192.168.240.3 -V -l 1452 -t 60 iperf version 3.0.1 (10 January 2014) Linux Lab200slot2 3.14.0+ #1 SMP Mon Apr 14 12:06:40 EDT 2014 x86_64 Time: Mon, 14 Apr 2014 16:40:48 GMT Connecting to host 192.168.240.3, port 5201 Cookie: Lab200slot2.1397493648.413274.65e131 [ 4] local 192.168.240.2 port 50548 connected to 192.168.240.3 port 5201 Starting Test: protocol: SCTP, 1 streams, 1452 byte blocks, omitting 0 seconds, 60 second test [ ID] Interval Transfer Bandwidth [ 4] 0.00-1.00 sec 240 MBytes 2.02 Gbits/sec [ 4] 1.00-2.00 sec 239 MBytes 2.01 Gbits/sec [ 4] 2.00-3.00 sec 240 MBytes 2.01 Gbits/sec [ 4] 3.00-4.00 sec 239 MBytes 2.00 Gbits/sec [ 4] 4.00-5.00 sec 245 MBytes 2.05 Gbits/sec [ 4] 5.00-6.00 sec 240 MBytes 2.01 Gbits/sec [ 4] 6.00-7.00 sec 240 MBytes 2.02 Gbits/sec [ 4] 7.00-8.00 sec 239 MBytes 2.01 Gbits/sec With the reverted patch applied, the SCTP/IPv4 performance is back to normal on latest upstream for IPv4 and IPv6 and has same throughput as 3.4.2 test kernel, steady and interval reports are smooth again. Fixes: ef2820a ("net: sctp: Fix a_rwnd/rwnd management to reflect real state of the receiver's buffer") Reported-by: Peter Butler <[email protected]> Reported-by: Dongsheng Song <[email protected]> Reported-by: Fengguang Wu <[email protected]> Tested-by: Peter Butler <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Cc: Matija Glavinic Pecotic <[email protected]> Cc: Alexander Sverdlin <[email protected]> Cc: Vlad Yasevich <[email protected]> Acked-by: Vlad Yasevich <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
parallella · May 31, 2014 · bde6d78 · bde6d78
1 parent 72beb56
commit bde6d78
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Showing 5 changed files with 87 additions and 25 deletions.
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
@@ -1653,6 +1653,17 @@ struct sctp_association {
 	/* This is the last advertised value of rwnd over a SACK chunk. */
 	__u32 a_rwnd;
 
+	/* Number of bytes by which the rwnd has slopped.  The rwnd is allowed
+	 * to slop over a maximum of the association's frag_point.
+	 */
+	__u32 rwnd_over;
+
+	/* Keeps treack of rwnd pressure.  This happens when we have
+	 * a window, but not recevie buffer (i.e small packets).  This one
+	 * is releases slowly (1 PMTU at a time ).
+	 */
+	__u32 rwnd_press;
+
 	/* This is the sndbuf size in use for the association.
 	 * This corresponds to the sndbuf size for the association,
 	 * as specified in the sk->sndbuf.
@@ -1881,7 +1892,8 @@ void sctp_assoc_update(struct sctp_association *old,
 __u32 sctp_association_get_next_tsn(struct sctp_association *);
 
 void sctp_assoc_sync_pmtu(struct sock *, struct sctp_association *);
-void sctp_assoc_rwnd_update(struct sctp_association *, bool);
+void sctp_assoc_rwnd_increase(struct sctp_association *, unsigned int);
+void sctp_assoc_rwnd_decrease(struct sctp_association *, unsigned int);
 void sctp_assoc_set_primary(struct sctp_association *,
 			    struct sctp_transport *);
 void sctp_assoc_del_nonprimary_peers(struct sctp_association *,

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
@@ -1396,35 +1396,44 @@ static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
 	return false;
 }
 
-/* Update asoc's rwnd for the approximated state in the buffer,
- * and check whether SACK needs to be sent.
- */
-void sctp_assoc_rwnd_update(struct sctp_association *asoc, bool update_peer)
+/* Increase asoc's rwnd by len and send any window update SACK if needed. */
+void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
 {
-	int rx_count;
 	struct sctp_chunk *sack;
 	struct timer_list *timer;
 
-	if (asoc->ep->rcvbuf_policy)
-		rx_count = atomic_read(&asoc->rmem_alloc);
-	else
-		rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
+	if (asoc->rwnd_over) {
+		if (asoc->rwnd_over >= len) {
+			asoc->rwnd_over -= len;
+		} else {
+			asoc->rwnd += (len - asoc->rwnd_over);
+			asoc->rwnd_over = 0;
+		}
+	} else {
+		asoc->rwnd += len;
+	}
 
-	if ((asoc->base.sk->sk_rcvbuf - rx_count) > 0)
-		asoc->rwnd = (asoc->base.sk->sk_rcvbuf - rx_count) >> 1;
-	else
-		asoc->rwnd = 0;
+	/* If we had window pressure, start recovering it
+	 * once our rwnd had reached the accumulated pressure
+	 * threshold.  The idea is to recover slowly, but up
+	 * to the initial advertised window.
+	 */
+	if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
+		int change = min(asoc->pathmtu, asoc->rwnd_press);
+		asoc->rwnd += change;
+		asoc->rwnd_press -= change;
+	}
 
-	pr_debug("%s: asoc:%p rwnd=%u, rx_count=%d, sk_rcvbuf=%d\n",
-		 __func__, asoc, asoc->rwnd, rx_count,
-		 asoc->base.sk->sk_rcvbuf);
+	pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
+		 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
+		 asoc->a_rwnd);
 
 	/* Send a window update SACK if the rwnd has increased by at least the
 	 * minimum of the association's PMTU and half of the receive buffer.
 	 * The algorithm used is similar to the one described in
 	 * Section 4.2.3.3 of RFC 1122.
 	 */
-	if (update_peer && sctp_peer_needs_update(asoc)) {
+	if (sctp_peer_needs_update(asoc)) {
 		asoc->a_rwnd = asoc->rwnd;
 
 		pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
@@ -1446,6 +1455,45 @@ void sctp_assoc_rwnd_update(struct sctp_association *asoc, bool update_peer)
 	}
 }
 
+/* Decrease asoc's rwnd by len. */
+void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
+{
+	int rx_count;
+	int over = 0;
+
+	if (unlikely(!asoc->rwnd || asoc->rwnd_over))
+		pr_debug("%s: association:%p has asoc->rwnd:%u, "
+			 "asoc->rwnd_over:%u!\n", __func__, asoc,
+			 asoc->rwnd, asoc->rwnd_over);
+
+	if (asoc->ep->rcvbuf_policy)
+		rx_count = atomic_read(&asoc->rmem_alloc);
+	else
+		rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
+
+	/* If we've reached or overflowed our receive buffer, announce
+	 * a 0 rwnd if rwnd would still be positive.  Store the
+	 * the potential pressure overflow so that the window can be restored
+	 * back to original value.
+	 */
+	if (rx_count >= asoc->base.sk->sk_rcvbuf)
+		over = 1;
+
+	if (asoc->rwnd >= len) {
+		asoc->rwnd -= len;
+		if (over) {
+			asoc->rwnd_press += asoc->rwnd;
+			asoc->rwnd = 0;
+		}
+	} else {
+		asoc->rwnd_over = len - asoc->rwnd;
+		asoc->rwnd = 0;
+	}
+
+	pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
+		 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
+		 asoc->rwnd_press);
+}
 
 /* Build the bind address list for the association based on info from the
  * local endpoint and the remote peer.

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
@@ -6178,7 +6178,7 @@ static int sctp_eat_data(const struct sctp_association *asoc,
 	 * PMTU.  In cases, such as loopback, this might be a rather
 	 * large spill over.
 	 */
-	if ((!chunk->data_accepted) && (!asoc->rwnd ||
+	if ((!chunk->data_accepted) && (!asoc->rwnd || asoc->rwnd_over ||
 	    (datalen > asoc->rwnd + asoc->frag_point))) {
 
 		/* If this is the next TSN, consider reneging to make

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
@@ -2115,6 +2115,12 @@ static int sctp_recvmsg(struct kiocb *iocb, struct sock *sk,
 		sctp_skb_pull(skb, copied);
 		skb_queue_head(&sk->sk_receive_queue, skb);
 
+		/* When only partial message is copied to the user, increase
+		 * rwnd by that amount. If all the data in the skb is read,
+		 * rwnd is updated when the event is freed.
+		 */
+		if (!sctp_ulpevent_is_notification(event))
+			sctp_assoc_rwnd_increase(event->asoc, copied);
 		goto out;
 	} else if ((event->msg_flags & MSG_NOTIFICATION) ||
 		   (event->msg_flags & MSG_EOR))

diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c
@@ -989,7 +989,7 @@ static void sctp_ulpevent_receive_data(struct sctp_ulpevent *event,
 	skb = sctp_event2skb(event);
 	/* Set the owner and charge rwnd for bytes received.  */
 	sctp_ulpevent_set_owner(event, asoc);
-	sctp_assoc_rwnd_update(asoc, false);
+	sctp_assoc_rwnd_decrease(asoc, skb_headlen(skb));
 
 	if (!skb->data_len)
 		return;
@@ -1011,7 +1011,6 @@ static void sctp_ulpevent_release_data(struct sctp_ulpevent *event)
 {
 	struct sk_buff *skb, *frag;
 	unsigned int	len;
-	struct sctp_association *asoc;
 
 	/* Current stack structures assume that the rcv buffer is
 	 * per socket.   For UDP style sockets this is not true as
@@ -1036,11 +1035,8 @@ static void sctp_ulpevent_release_data(struct sctp_ulpevent *event)
 	}
 
 done:
-	asoc = event->asoc;
-	sctp_association_hold(asoc);
+	sctp_assoc_rwnd_increase(event->asoc, len);
 	sctp_ulpevent_release_owner(event);
-	sctp_assoc_rwnd_update(asoc, true);
-	sctp_association_put(asoc);
 }
 
 static void sctp_ulpevent_release_frag_data(struct sctp_ulpevent *event)