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2016-07-30tcp: consider recv buf for the initial window scaleSoheil Hassas Yeganeh1-1/+2
tcp_select_initial_window() intends to advertise a window scaling for the maximum possible window size. To do so, it considers the maximum of net.ipv4.tcp_rmem[2] and net.core.rmem_max as the only possible upper-bounds. However, users with CAP_NET_ADMIN can use SO_RCVBUFFORCE to set the socket's receive buffer size to values larger than net.ipv4.tcp_rmem[2] and net.core.rmem_max. Thus, SO_RCVBUFFORCE is effectively ignored by tcp_select_initial_window(). To fix this, consider the maximum of net.ipv4.tcp_rmem[2], net.core.rmem_max and socket's initial buffer space. Fixes: b0573dea1fb3 ("[NET]: Introduce SO_{SND,RCV}BUFFORCE socket options") Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Suggested-by: Neal Cardwell <ncardwell@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-30Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-1/+6
Several cases of overlapping changes, except the packet scheduler conflicts which deal with the addition of the free list parameter to qdisc_enqueue(). Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-29tcp: do not send too big packets at retransmit timeEric Dumazet1-1/+6
Arjun reported a bug in TCP stack and bisected it to a recent commit. In case where we process SACK, we can coalesce multiple skbs into fat ones (tcp_shift_skb_data()), to lower write queue overhead, because we do not expect to retransmit these packets. However, SACK reneging can happen, forcing the sender to retransmit all these packets. If skb->len is above 64KB, we then send buggy IP packets that could hang TSO engine on cxgb4. Neal suggested to use tcp_tso_autosize() instead of tp->gso_segs so that we cook packets of optimal size vs TCP/pacing. Thanks to Arjun for reporting the bug and running the tests ! Fixes: 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Arjun V <arjun@chelsio.com> Tested-by: Arjun V <arjun@chelsio.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-10tcp: add in_flight to tcp_skb_cbLawrence Brakmo1-1/+3
Add in_flight (bytes in flight when packet was sent) field to tx component of tcp_skb_cb and make it available to congestion modules' pkts_acked() function through the ack_sample function argument. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-16tcp: minor optimizations around tcp_hdr() usageEric Dumazet1-16/+14
tcp_hdr() is slightly more expensive than using skb->data in contexts where we know they point to the same byte. In receive path, tcp_v4_rcv() and tcp_v6_rcv() are in this situation, as tcp header has not been pulled yet. In output path, the same can be said when we just pushed the tcp header in the skb, in tcp_transmit_skb() and tcp_make_synack() Also factorize the two checks for tcb->tcp_flags & TCPHDR_SYN in tcp_transmit_skb() and pass tcp header pointer to tcp_ecn_send(), so that compiler can further optimize and avoid a reload. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-15Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-2/+4
The nf_conntrack_core.c fix in 'net' is not relevant in 'net-next' because we no longer have a per-netns conntrack hash. The ip_gre.c conflict as well as the iwlwifi ones were cases of overlapping changes. Conflicts: drivers/net/wireless/intel/iwlwifi/mvm/tx.c net/ipv4/ip_gre.c net/netfilter/nf_conntrack_core.c Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-10tcp: refresh skb timestamp at retransmit timeEric Dumazet1-2/+4
In the very unlikely case __tcp_retransmit_skb() can not use the cloning done in tcp_transmit_skb(), we need to refresh skb_mstamp before doing the copy and transmit, otherwise TCP TS val will be an exact copy of original transmit. Fixes: 7faee5c0d514 ("tcp: remove TCP_SKB_CB(skb)->when") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-03net: add __sock_wfree() helperEric Dumazet1-1/+1
Hosts sending lot of ACK packets exhibit high sock_wfree() cost because of cache line miss to test SOCK_USE_WRITE_QUEUE We could move this flag close to sk_wmem_alloc but it is better to perform the atomic_sub_and_test() on a clean cache line, as it avoid one extra bus transaction. skb_orphan_partial() can also have a fast track for packets that either are TCP acks, or already went through another skb_orphan_partial() Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-02tcp: do not assume TCP code is non preemptibleEric Dumazet1-6/+5
We want to to make TCP stack preemptible, as draining prequeue and backlog queues can take lot of time. Many SNMP updates were assuming that BH (and preemption) was disabled. Need to convert some __NET_INC_STATS() calls to NET_INC_STATS() and some __TCP_INC_STATS() to TCP_INC_STATS() Before using this_cpu_ptr(net->ipv4.tcp_sk) in tcp_v4_send_reset() and tcp_v4_send_ack(), we add an explicit preempt disabled section. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-28tcp: Handle eor bit when fragmenting a skbMartin KaFai Lau1-0/+9
When fragmenting a skb, the next_skb should carry the eor from prev_skb. The eor of prev_skb should also be reset. Packetdrill script for testing: ~~~~~~ +0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10` +0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7> 0.100 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7> 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 0.200 sendto(4, ..., 15330, MSG_EOR, ..., ...) = 15330 0.200 sendto(4, ..., 730, 0, ..., ...) = 730 0.200 > . 1:7301(7300) ack 1 0.200 > . 7301:14601(7300) ack 1 0.300 < . 1:1(0) ack 14601 win 257 0.300 > P. 14601:15331(730) ack 1 0.300 > P. 15331:16061(730) ack 1 0.400 < . 1:1(0) ack 16061 win 257 0.400 close(4) = 0 0.400 > F. 16061:16061(0) ack 1 0.400 < F. 1:1(0) ack 16062 win 257 0.400 > . 16062:16062(0) ack 2 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-28tcp: Handle eor bit when coalescing skbMartin KaFai Lau1-0/+4
This patch: 1. Prevent next_skb from coalescing to the prev_skb if TCP_SKB_CB(prev_skb)->eor is set 2. Update the TCP_SKB_CB(prev_skb)->eor if coalescing is allowed Packetdrill script for testing: ~~~~~~ +0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10` +0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7> 0.100 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7> 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 0.200 sendto(4, ..., 730, MSG_EOR, ..., ...) = 730 0.200 sendto(4, ..., 730, MSG_EOR, ..., ...) = 730 0.200 write(4, ..., 11680) = 11680 0.200 > P. 1:731(730) ack 1 0.200 > P. 731:1461(730) ack 1 0.200 > . 1461:8761(7300) ack 1 0.200 > P. 8761:13141(4380) ack 1 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:13141,nop,nop> 0.300 > P. 1:731(730) ack 1 0.300 > P. 731:1461(730) ack 1 0.400 < . 1:1(0) ack 13141 win 257 0.400 close(4) = 0 0.400 > F. 13141:13141(0) ack 1 0.500 < F. 1:1(0) ack 13142 win 257 0.500 > . 13142:13142(0) ack 2 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-28tcp: remove SKBTX_ACK_TSTAMP since it is redundantSoheil Hassas Yeganeh1-6/+11
The SKBTX_ACK_TSTAMP flag is set in skb_shinfo->tx_flags when the timestamp of the TCP acknowledgement should be reported on error queue. Since accessing skb_shinfo is likely to incur a cache-line miss at the time of receiving the ack, the txstamp_ack bit was added in tcp_skb_cb, which is set iff the SKBTX_ACK_TSTAMP flag is set for an skb. This makes SKBTX_ACK_TSTAMP flag redundant. Remove the SKBTX_ACK_TSTAMP and instead use the txstamp_ack bit everywhere. Note that this frees one bit in shinfo->tx_flags. Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Suggested-by: Willem de Bruijn <willemb@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-27net: rename NET_{ADD|INC}_STATS_BH()Eric Dumazet1-7/+7
Rename NET_INC_STATS_BH() to __NET_INC_STATS() and NET_ADD_STATS_BH() to __NET_ADD_STATS() Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-27net: tcp: rename TCP_INC_STATS_BHEric Dumazet1-2/+2
Rename TCP_INC_STATS_BH() to __TCP_INC_STATS() Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24tcp-tso: do not split TSO packets at retransmit timeEric Dumazet1-35/+29
Linux TCP stack painfully segments all TSO/GSO packets before retransmits. This was fine back in the days when TSO/GSO were emerging, with their bugs, but we believe the dark age is over. Keeping big packets in write queues, but also in stack traversal has a lot of benefits. - Less memory overhead, because write queues have less skbs - Less cpu overhead at ACK processing. - Better SACK processing, as lot of studies mentioned how awful linux was at this ;) - Less cpu overhead to send the rtx packets (IP stack traversal, netfilter traversal, drivers...) - Better latencies in presence of losses. - Smaller spikes in fq like packet schedulers, as retransmits are not constrained by TCP Small Queues. 1 % packet losses are common today, and at 100Gbit speeds, this translates to ~80,000 losses per second. Losses are often correlated, and we see many retransmit events leading to 1-MSS train of packets, at the time hosts are already under stress. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24tcp: Merge txstamp_ack in tcp_skb_collapse_tstampMartin KaFai Lau1-0/+2
When collapsing skbs, txstamp_ack also needs to be merged. Retrans Collapse Test: ~~~~~~ 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 0.200 write(4, ..., 730) = 730 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 write(4, ..., 730) = 730 +0 setsockopt(4, SOL_SOCKET, 37, [2176], 4) = 0 0.200 write(4, ..., 11680) = 11680 0.200 > P. 1:731(730) ack 1 0.200 > P. 731:1461(730) ack 1 0.200 > . 1461:8761(7300) ack 1 0.200 > P. 8761:13141(4380) ack 1 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:2921,nop,nop> 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:4381,nop,nop> 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:5841,nop,nop> 0.300 > P. 1:1461(1460) ack 1 0.400 < . 1:1(0) ack 13141 win 257 BPF Output Before: ~~~~~ <No output due to missing SCM_TSTAMP_ACK timestamp> BPF Output After: ~~~~~ <...>-2027 [007] d.s. 79.765921: : ee_data:1459 Sacks Collapse Test: ~~~~~ 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 0.200 write(4, ..., 1460) = 1460 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 write(4, ..., 13140) = 13140 +0 setsockopt(4, SOL_SOCKET, 37, [2176], 4) = 0 0.200 > P. 1:1461(1460) ack 1 0.200 > . 1461:8761(7300) ack 1 0.200 > P. 8761:14601(5840) ack 1 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:14601,nop,nop> 0.300 > P. 1:1461(1460) ack 1 0.400 < . 1:1(0) ack 14601 win 257 BPF Output Before: ~~~~~ <No output due to missing SCM_TSTAMP_ACK timestamp> BPF Output After: ~~~~~ <...>-2049 [007] d.s. 89.185538: : ee_data:14599 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Tested-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-24tcp: Carry txstamp_ack in tcp_fragment_tstampMartin KaFai Lau1-0/+2
When a tcp skb is sliced into two smaller skbs (e.g. in tcp_fragment() and tso_fragment()), it does not carry the txstamp_ack bit to the newly created skb if it is needed. The end result is a timestamping event (SCM_TSTAMP_ACK) will be missing from the sk->sk_error_queue. This patch carries this bit to the new skb2 in tcp_fragment_tstamp(). BPF Output Before: ~~~~~~ <No output due to missing SCM_TSTAMP_ACK timestamp> BPF Output After: ~~~~~~ <...>-2050 [000] d.s. 100.928763: : ee_data:14599 Packetdrill Script: ~~~~~~ +0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10` +0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7> 0.100 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7> 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 write(4, ..., 14600) = 14600 +0 setsockopt(4, SOL_SOCKET, 37, [2176], 4) = 0 0.200 > . 1:7301(7300) ack 1 0.200 > P. 7301:14601(7300) ack 1 0.300 < . 1:1(0) ack 14601 win 257 0.300 close(4) = 0 0.300 > F. 14601:14601(0) ack 1 0.400 < F. 1:1(0) ack 16062 win 257 0.400 > . 14602:14602(0) ack 2 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Tested-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-23Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-0/+16
Conflicts were two cases of simple overlapping changes, nothing serious. In the UDP case, we need to add a hlist_add_tail_rcu() to linux/rculist.h, because we've moved UDP socket handling away from using nulls lists. Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-21tcp: Merge tx_flags and tskey in tcp_shifted_skbMartin KaFai Lau1-2/+2
After receiving sacks, tcp_shifted_skb() will collapse skbs if possible. tx_flags and tskey also have to be merged. This patch reuses the tcp_skb_collapse_tstamp() to handle them. BPF Output Before: ~~~~~ <no-output-due-to-missing-tstamp-event> BPF Output After: ~~~~~ <...>-2024 [007] d.s. 88.644374: : ee_data:14599 Packetdrill Script: ~~~~~ +0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10` +0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7> 0.100 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7> 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 0.200 write(4, ..., 1460) = 1460 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 write(4, ..., 13140) = 13140 0.200 > P. 1:1461(1460) ack 1 0.200 > . 1461:8761(7300) ack 1 0.200 > P. 8761:14601(5840) ack 1 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:14601,nop,nop> 0.300 > P. 1:1461(1460) ack 1 0.400 < . 1:1(0) ack 14601 win 257 0.400 close(4) = 0 0.400 > F. 14601:14601(0) ack 1 0.500 < F. 1:1(0) ack 14602 win 257 0.500 > . 14602:14602(0) ack 2 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Tested-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-21tcp: Merge tx_flags and tskey in tcp_collapse_retransMartin KaFai Lau1-0/+16
If two skbs are merged/collapsed during retransmission, the current logic does not merge the tx_flags and tskey. The end result is the SCM_TSTAMP_ACK timestamp could be missing for a packet. The patch: 1. Merge the tx_flags 2. Overwrite the prev_skb's tskey with the next_skb's tskey BPF Output Before: ~~~~~~ <no-output-due-to-missing-tstamp-event> BPF Output After: ~~~~~~ packetdrill-2092 [001] d.s. 453.998486: : ee_data:1459 Packetdrill Script: ~~~~~~ +0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10` +0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7> 0.100 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7> 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 0.200 write(4, ..., 730) = 730 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 write(4, ..., 730) = 730 +0 setsockopt(4, SOL_SOCKET, 37, [2176], 4) = 0 0.200 write(4, ..., 11680) = 11680 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 > P. 1:731(730) ack 1 0.200 > P. 731:1461(730) ack 1 0.200 > . 1461:8761(7300) ack 1 0.200 > P. 8761:13141(4380) ack 1 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:2921,nop,nop> 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:4381,nop,nop> 0.300 < . 1:1(0) ack 1 win 257 <sack 1461:5841,nop,nop> 0.300 > P. 1:1461(1460) ack 1 0.400 < . 1:1(0) ack 13141 win 257 0.400 close(4) = 0 0.400 > F. 13141:13141(0) ack 1 0.500 < F. 1:1(0) ack 13142 win 257 0.500 > . 13142:13142(0) ack 2 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Tested-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-15tcp: do not mess with listener sk_wmem_allocEric Dumazet1-4/+12
When removing sk_refcnt manipulation on synflood, I missed that using skb_set_owner_w() was racy, if sk->sk_wmem_alloc had already transitioned to 0. We should hold sk_refcnt instead, but this is a big deal under attack. (Doing so increase performance from 3.2 Mpps to 3.8 Mpps only) In this patch, I chose to not attach a socket to syncookies skb. Performance is now 5 Mpps instead of 3.2 Mpps. Following patch will remove last known false sharing in tcp_rcv_state_process() Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-03-14tcp: Add RFC4898 tcpEStatsPerfDataSegsOut/InMartin KaFai Lau1-1/+3
Per RFC4898, they count segments sent/received containing a positive length data segment (that includes retransmission segments carrying data). Unlike tcpi_segs_out/in, tcpi_data_segs_out/in excludes segments carrying no data (e.g. pure ack). The patch also updates the segs_in in tcp_fastopen_add_skb() so that segs_in >= data_segs_in property is kept. Together with retransmission data, tcpi_data_segs_out gives a better signal on the rxmit rate. v6: Rebase on the latest net-next v5: Eric pointed out that checking skb->len is still needed in tcp_fastopen_add_skb() because skb can carry a FIN without data. Hence, instead of open coding segs_in and data_segs_in, tcp_segs_in() helper is used. Comment is added to the fastopen case to explain why segs_in has to be reset and tcp_segs_in() has to be called before __skb_pull(). v4: Add comment to the changes in tcp_fastopen_add_skb() and also add remark on this case in the commit message. v3: Add const modifier to the skb parameter in tcp_segs_in() v2: Rework based on recent fix by Eric: commit a9d99ce28ed3 ("tcp: fix tcpi_segs_in after connection establishment") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Chris Rapier <rapier@psc.edu> Cc: Eric Dumazet <edumazet@google.com> Cc: Marcelo Ricardo Leitner <mleitner@redhat.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-02-07ipv4: Namespaceify tcp_notsent_lowat sysctl knobNikolay Borisov1-3/+0
Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-02-07ipv4: Namespaceify tcp_retries2 sysctl knobNikolay Borisov1-1/+2
Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-01-14net: tcp_memcontrol: simplify linkage between socket and page counterJohannes Weiner1-2/+2
There won't be any separate counters for socket memory consumed by protocols other than TCP in the future. Remove the indirection and link sockets directly to their owning memory cgroup. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14net: tcp_memcontrol: sanitize tcp memory accounting callbacksJohannes Weiner1-2/+5
There won't be a tcp control soft limit, so integrating the memcg code into the global skmem limiting scheme complicates things unnecessarily. Replace this with simple and clear charge and uncharge calls--hidden behind a jump label--to account skb memory. Note that this is not purely aesthetic: as a result of shoehorning the per-memcg code into the same memory accounting functions that handle the global level, the old code would compare the per-memcg consumption against the smaller of the per-memcg limit and the global limit. This allowed the total consumption of multiple sockets to exceed the global limit, as long as the individual sockets stayed within bounds. After this change, the code will always compare the per-memcg consumption to the per-memcg limit, and the global consumption to the global limit, and thus close this loophole. Without a soft limit, the per-memcg memory pressure state in sockets is generally questionable. However, we did it until now, so we continue to enter it when the hard limit is hit, and packets are dropped, to let other sockets in the cgroup know that they shouldn't grow their transmit windows, either. However, keep it simple in the new callback model and leave memory pressure lazily when the next packet is accepted (as opposed to doing it synchroneously when packets are processed). When packets are dropped, network performance will already be in the toilet, so that should be a reasonable trade-off. As described above, consumption is now checked on the per-memcg level and the global level separately. Likewise, memory pressure states are maintained on both the per-memcg level and the global level, and a socket is considered under pressure when either level asserts as much. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-17Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-11/+12
Conflicts: drivers/net/geneve.c Here we had an overlapping change, where in 'net' the extraneous stats bump was being removed whilst in 'net-next' the final argument to udp_tunnel6_xmit_skb() was being changed. Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-17tcp: restore fastopen with no data in SYN packetEric Dumazet1-11/+12
Yuchung tracked a regression caused by commit 57be5bdad759 ("ip: convert tcp_sendmsg() to iov_iter primitives") for TCP Fast Open. Some Fast Open users do not actually add any data in the SYN packet. Fixes: 57be5bdad759 ("ip: convert tcp_sendmsg() to iov_iter primitives") Reported-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-02tcp: suppress too verbose messages in tcp_send_ack()Eric Dumazet1-6/+8
If tcp_send_ack() can not allocate skb, we properly handle this and setup a timer to try later. Use __GFP_NOWARN to avoid polluting syslog in the case host is under memory pressure, so that pertinent messages are not lost under a flood of useless information. sk_gfp_atomic() can use its gfp_mask argument (all callers currently were using GFP_ATOMIC before this patch) We rename sk_gfp_atomic() to sk_gfp_mask() to clearly express this function now takes into account its second argument (gfp_mask) Note that when tcp_transmit_skb() is called with clone_it set to false, we do not attempt memory allocations, so can pass a 0 gfp_mask, which most compilers can emit faster than a non zero or constant value. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-11-02net: make skb_set_owner_w() more robustEric Dumazet1-3/+1
skb_set_owner_w() is called from various places that assume skb->sk always point to a full blown socket (as it changes sk->sk_wmem_alloc) We'd like to attach skb to request sockets, and in the future to timewait sockets as well. For these kind of pseudo sockets, we need to take a traditional refcount and use sock_edemux() as the destructor. It is now time to un-inline skb_set_owner_w(), being too big. Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener") Signed-off-by: Eric Dumazet <edumazet@google.com> Bisected-by: Haiyang Zhang <haiyangz@microsoft.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-24Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-1/+1
Conflicts: net/ipv6/xfrm6_output.c net/openvswitch/flow_netlink.c net/openvswitch/vport-gre.c net/openvswitch/vport-vxlan.c net/openvswitch/vport.c net/openvswitch/vport.h The openvswitch conflicts were overlapping changes. One was the egress tunnel info fix in 'net' and the other was the vport ->send() op simplification in 'net-next'. The xfrm6_output.c conflicts was also a simplification overlapping a bug fix. Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-21tcp: remove improper preemption check in tcp_xmit_probe_skb()Renato Westphal1-1/+1
Commit e520af48c7e5a introduced the following bug when setting the TCP_REPAIR sockoption: [ 2860.657036] BUG: using __this_cpu_add() in preemptible [00000000] code: daemon/12164 [ 2860.657045] caller is __this_cpu_preempt_check+0x13/0x20 [ 2860.657049] CPU: 1 PID: 12164 Comm: daemon Not tainted 4.2.3 #1 [ 2860.657051] Hardware name: Dell Inc. PowerEdge R210 II/0JP7TR, BIOS 2.0.5 03/13/2012 [ 2860.657054] ffffffff81c7f071 ffff880231e9fdf8 ffffffff8185d765 0000000000000002 [ 2860.657058] 0000000000000001 ffff880231e9fe28 ffffffff8146ed91 ffff880231e9fe18 [ 2860.657062] ffffffff81cd1a5d ffff88023534f200 ffff8800b9811000 ffff880231e9fe38 [ 2860.657065] Call Trace: [ 2860.657072] [<ffffffff8185d765>] dump_stack+0x4f/0x7b [ 2860.657075] [<ffffffff8146ed91>] check_preemption_disabled+0xe1/0xf0 [ 2860.657078] [<ffffffff8146edd3>] __this_cpu_preempt_check+0x13/0x20 [ 2860.657082] [<ffffffff817e0bc7>] tcp_xmit_probe_skb+0xc7/0x100 [ 2860.657085] [<ffffffff817e1e2d>] tcp_send_window_probe+0x2d/0x30 [ 2860.657089] [<ffffffff817d1d8c>] do_tcp_setsockopt.isra.29+0x74c/0x830 [ 2860.657093] [<ffffffff817d1e9c>] tcp_setsockopt+0x2c/0x30 [ 2860.657097] [<ffffffff81767b74>] sock_common_setsockopt+0x14/0x20 [ 2860.657100] [<ffffffff817669e1>] SyS_setsockopt+0x71/0xc0 [ 2860.657104] [<ffffffff81865172>] entry_SYSCALL_64_fastpath+0x16/0x75 Since tcp_xmit_probe_skb() can be called from process context, use NET_INC_STATS() instead of NET_INC_STATS_BH(). Fixes: e520af48c7e5 ("tcp: add TCPWinProbe and TCPKeepAlive SNMP counters") Signed-off-by: Renato Westphal <renatow@taghos.com.br> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-21tcp: remove tcp_mark_lost_retrans()Yuchung Cheng1-6/+0
Remove the existing lost retransmit detection because RACK subsumes it completely. This also stops the overloading the ack_seq field of the skb control block. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-18tcp: do not set queue_mapping on SYNACKEric Dumazet1-1/+1
At the time of commit fff326990789 ("tcp: reflect SYN queue_mapping into SYNACK packets") we had little ways to cope with SYN floods. We no longer need to reflect incoming skb queue mappings, and instead can pick a TX queue based on cpu cooking the SYNACK, with normal XPS affinities. Note that all SYNACK retransmits were picking TX queue 0, this no longer is a win given that SYNACK rtx are now distributed on all cpus. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-12net: shrink struct sock and request_sock by 8 bytesEric Dumazet1-1/+1
One 32bit hole is following skc_refcnt, use it. skc_incoming_cpu can also be an union for request_sock rcv_wnd. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-03tcp: attach SYNACK messages to request sockets instead of listenerEric Dumazet1-7/+15
If a listen backlog is very big (to avoid syncookies), then the listener sk->sk_wmem_alloc is the main source of false sharing, as we need to touch it twice per SYNACK re-transmit and TX completion. (One SYN packet takes listener lock once, but up to 6 SYNACK are generated) By attaching the skb to the request socket, we remove this source of contention. Tested: listen(fd, 10485760); // single listener (no SO_REUSEPORT) 16 RX/TX queue NIC Sustain a SYNFLOOD attack of ~320,000 SYN per second, Sending ~1,400,000 SYNACK per second. Perf profiles now show listener spinlock being next bottleneck. 20.29% [kernel] [k] queued_spin_lock_slowpath 10.06% [kernel] [k] __inet_lookup_established 5.12% [kernel] [k] reqsk_timer_handler 3.22% [kernel] [k] get_next_timer_interrupt 3.00% [kernel] [k] tcp_make_synack 2.77% [kernel] [k] ipt_do_table 2.70% [kernel] [k] run_timer_softirq 2.50% [kernel] [k] ip_finish_output 2.04% [kernel] [k] cascade Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-28tcp: Fix CWV being too strict on thin streamsBendik Rønning Opstad1-2/+2
Application limited streams such as thin streams, that transmit small amounts of payload in relatively few packets per RTT, can be prevented from growing the CWND when in congestion avoidance. This leads to increased sojourn times for data segments in streams that often transmit time-dependent data. Currently, a connection is considered CWND limited only after having successfully transmitted at least one packet with new data, while at the same time failing to transmit some unsent data from the output queue because the CWND is full. Applications that produce small amounts of data may be left in a state where it is never considered to be CWND limited, because all unsent data is successfully transmitted each time an incoming ACK opens up for more data to be transmitted in the send window. Fix by always testing whether the CWND is fully used after successful packet transmissions, such that a connection is considered CWND limited whenever the CWND has been filled. This is the correct behavior as specified in RFC2861 (section 3.1). Cc: Andreas Petlund <apetlund@simula.no> Cc: Carsten Griwodz <griff@simula.no> Cc: Jonas Markussen <jonassm@ifi.uio.no> Cc: Kenneth Klette Jonassen <kennetkl@ifi.uio.no> Cc: Mads Johannessen <madsjoh@ifi.uio.no> Signed-off-by: Bendik Rønning Opstad <bro.devel+kernel@gmail.com> Acked-by: Eric Dumazet <edumazet@google.com> Tested-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Tested-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-26Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-0/+1
Conflicts: net/ipv4/arp.c The net/ipv4/arp.c conflict was one commit adding a new local variable while another commit was deleting one. Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-25tcp/dccp: constify rtx_synack() and friendsEric Dumazet1-1/+1
This is done to make sure we do not change listener socket while sending SYNACK packets while socket lock is not held. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-25tcp: constify tcp_make_synack() socket argumentEric Dumazet1-9/+15
listener socket is not locked when tcp_make_synack() is called. We better make sure no field is written. There is one exception : Since SYNACK packets are attached to the listener at this moment (or SYN_RECV child in case of Fast Open), sock_wmalloc() needs to update sk->sk_wmem_alloc, but this is done using atomic operations so this is safe. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-25tcp: remove tcp_ecn_make_synack() socket argumentEric Dumazet1-7/+3
SYNACK packets might be sent without holding socket lock. For DCTCP/ECN sake, we should call INET_ECN_xmit() while socket lock is owned, and only when we init/change congestion control. This also fixies a bug if congestion module is changed from dctcp to another one on a listener : we now clear ECN bits properly. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-25tcp: remove tcp_synack_options() socket argumentEric Dumazet1-8/+7
We do not use the socket in this function. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-23tcp: add proper TS val into RST packetsEric Dumazet1-0/+1
RST packets sent on behalf of TCP connections with TS option (RFC 7323 TCP timestamps) have incorrect TS val (set to 0), but correct TS ecr. A > B: Flags [S], seq 0, win 65535, options [mss 1000,nop,nop,TS val 100 ecr 0], length 0 B > A: Flags [S.], seq 2444755794, ack 1, win 28960, options [mss 1460,nop,nop,TS val 7264344 ecr 100], length 0 A > B: Flags [.], ack 1, win 65535, options [nop,nop,TS val 110 ecr 7264344], length 0 B > A: Flags [R.], seq 1, ack 1, win 28960, options [nop,nop,TS val 0 ecr 110], length 0 We need to call skb_mstamp_get() to get proper TS val, derived from skb->skb_mstamp Note that RFC 1323 was advocating to not send TS option in RST segment, but RFC 7323 recommends the opposite : Once TSopt has been successfully negotiated, that is both <SYN> and <SYN,ACK> contain TSopt, the TSopt MUST be sent in every non-<RST> segment for the duration of the connection, and SHOULD be sent in an <RST> segment (see Section 5.2 for details) Note this RFC recommends to send TS val = 0, but we believe it is premature : We do not know if all TCP stacks are properly handling the receive side : When an <RST> segment is received, it MUST NOT be subjected to the PAWS check by verifying an acceptable value in SEG.TSval, and information from the Timestamps option MUST NOT be used to update connection state information. SEG.TSecr MAY be used to provide stricter <RST> acceptance checks. In 5 years, if/when all TCP stack are RFC 7323 ready, we might consider to decide to send TS val = 0, if it buys something. Fixes: 7faee5c0d514 ("tcp: remove TCP_SKB_CB(skb)->when") Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-21tcp: send loss probe after 1s if no RTT availableYuchung Cheng1-4/+5
This patch makes TLP to use 1 sec timer by default when RTT is not available due to SYN/ACK retransmission or SYN cookies. Prior to this change, the lack of RTT prevents TLP so the first data packets sent can only be recovered by fast recovery or RTO. If the fast recovery fails to trigger the RTO is 3 second when SYN/ACK is retransmitted. With this patch we can trigger fast recovery in 1sec instead. Note that we need to check Fast Open more properly. A Fast Open connection could be (accepted then) closed before it receives the final ACK of 3WHS so the state is FIN_WAIT_1. Without the new check, TLP will retransmit FIN instead of SYN/ACK. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Nandita Dukkipati <nanditad@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-17tcp: provide skb->hash to synack packetsEric Dumazet1-0/+2
In commit b73c3d0e4f0e ("net: Save TX flow hash in sock and set in skbuf on xmit"), Tom provided a l4 hash to most outgoing TCP packets. We'd like to provide one as well for SYNACK packets, so that all packets of a given flow share same txhash, to later enable bonding driver to also use skb->hash to perform slave selection. Note that a SYNACK retransmit shuffles the tx hash, as Tom did in commit 265f94ff54d62 ("net: Recompute sk_txhash on negative routing advice") for established sockets. This has nice effect making TCP flows resilient to some kind of black holes, even at connection establish phase. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Tom Herbert <tom@herbertland.com> Cc: Mahesh Bandewar <maheshb@google.com> Acked-by: Tom Herbert <tom@herbertland.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-10tcp: generate CA_EVENT_TX_START on data framesNeal Cardwell1-3/+3
Issuing a CC TX_START event on control frames like pure ACK is a waste of time, as a CC should not care. Following patch needs this change, as we want CUBIC to properly track idle time at a low cost, with a single TX_START being generated. Yuchung might slightly refine the condition triggering TX_START on a followup patch. Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Cc: Jana Iyengar <jri@google.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: Sangtae Ha <sangtae.ha@gmail.com> Cc: Lawrence Brakmo <lawrence@brakmo.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-08-25tcp: fix slow start after idle vs TSO/GSOEric Dumazet1-8/+4
slow start after idle might reduce cwnd, but we perform this after first packet was cooked and sent. With TSO/GSO, it means that we might send a full TSO packet even if cwnd should have been reduced to IW10. Moving the SSAI check in skb_entail() makes sense, because we slightly reduce number of times this check is done, especially for large send() and TCP Small queue callbacks from softirq context. As Neal pointed out, we also need to perform the check if/when receive window opens. Tested: Following packetdrill test demonstrates the problem // Test of slow start after idle `sysctl -q net.ipv4.tcp_slow_start_after_idle=1` 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 +0 < S 0:0(0) win 65535 <mss 1000,sackOK,nop,nop,nop,wscale 7> +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 6> +.100 < . 1:1(0) ack 1 win 511 +0 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_SOCKET, SO_SNDBUF, [200000], 4) = 0 +0 write(4, ..., 26000) = 26000 +0 > . 1:5001(5000) ack 1 +0 > . 5001:10001(5000) ack 1 +0 %{ assert tcpi_snd_cwnd == 10 }% +.100 < . 1:1(0) ack 10001 win 511 +0 %{ assert tcpi_snd_cwnd == 20, tcpi_snd_cwnd }% +0 > . 10001:20001(10000) ack 1 +0 > P. 20001:26001(6000) ack 1 +.100 < . 1:1(0) ack 26001 win 511 +0 %{ assert tcpi_snd_cwnd == 36, tcpi_snd_cwnd }% +4 write(4, ..., 20000) = 20000 // If slow start after idle works properly, we should send 5 MSS here (cwnd/2) +0 > . 26001:31001(5000) ack 1 +0 %{ assert tcpi_snd_cwnd == 10, tcpi_snd_cwnd }% +0 > . 31001:36001(5000) ack 1 Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-08-13tcp: TLP retransmits last if failed to send new packetYuchung Cheng1-16/+22
When TLP fails to send new packet because of receive window limit, it should fall back to retransmit the last packet instead. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Nandita Dukkipati <nanditad@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-08-13tcp: don't extend RTO on failed loss probe attemptsYuchung Cheng1-7/+6
If TLP was unable to send a probe, it extended the RTO to now + icsk_rto. But extending the RTO makes little sense if no TLP probe went out. With this commit, instead of extending the RTO we re-arm it relative to the transmit time of the write queue head. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Nandita Dukkipati <nanditad@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-07-27tcp: tso: allow deferring under reordering stateEric Dumazet1-1/+1
While doing experiments with reordering resilience, we found linux senders were not able to send at full speed under reordering, because every incoming SACK was releasing one MSS. This patch removes the limitation, as we did for CWR state in commit a0ea700e409 ("tcp: tso: allow CA_CWR state in tcp_tso_should_defer()") Neal Cardwell had a concern about limited transmit so Yuchung conducted experiments on GFE and found nothing worth adding an extra check on fast path : if (icsk->icsk_ca_state == TCP_CA_Disorder && tcp_sk(sk)->reordering == sysctl_tcp_reordering) goto send_now; Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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