From 362d52040c71f6e8d8158be48c812d7729cb8df1 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 14 Apr 2014 21:45:17 +0200 Subject: Revert "net: sctp: Fix a_rwnd/rwnd management to reflect real state of the receiver's buffer" This reverts commit ef2820a735f7 ("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: ef2820a735f7 ("net: sctp: Fix a_rwnd/rwnd management to reflect real state of the receiver's buffer") Reported-by: Peter Butler Reported-by: Dongsheng Song Reported-by: Fengguang Wu Tested-by: Peter Butler Signed-off-by: Daniel Borkmann Cc: Matija Glavinic Pecotic Cc: Alexander Sverdlin Cc: Vlad Yasevich Acked-by: Vlad Yasevich Signed-off-by: David S. Miller --- net/sctp/associola.c | 82 +++++++++++++++++++++++++++++++++++++++---------- net/sctp/sm_statefuns.c | 2 +- net/sctp/socket.c | 6 ++++ net/sctp/ulpevent.c | 8 ++--- 4 files changed, 74 insertions(+), 24 deletions(-) (limited to 'net') diff --git a/net/sctp/associola.c b/net/sctp/associola.c index 4f6d6f9d1274..39579c3e0d14 100644 --- a/net/sctp/associola.c +++ b/net/sctp/associola.c @@ -1395,35 +1395,44 @@ 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 " @@ -1445,6 +1454,45 @@ 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 index 01e002430c85..ae9fbeba40b0 100644 --- 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 index e13519e9df80..ff20e2dbbbc7 100644 --- 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 index 8d198ae03606..85c64658bd0b 100644 --- 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) -- cgit v1.2.3