path: root/net/ipv4/tcp_timer.c
diff options
authorYuchung Cheng <ycheng@google.com>2013-03-20 13:32:58 +0000
committerDavid S. Miller <davem@davemloft.net>2013-03-21 11:47:50 -0400
commit9b44190dc114c1720b34975b5bfc65aece112ced (patch)
treec1202e05d6a04fa1d31be2ad2942fbe32ffa3f76 /net/ipv4/tcp_timer.c
parentfilter: add minimal BPF JIT image disassembler (diff)
tcp: refactor F-RTO
The patch series refactor the F-RTO feature (RFC4138/5682). This is to simplify the loss recovery processing. Existing F-RTO was developed during the experimental stage (RFC4138) and has many experimental features. It takes a separate code path from the traditional timeout processing by overloading CA_Disorder instead of using CA_Loss state. This complicates CA_Disorder state handling because it's also used for handling dubious ACKs and undos. While the algorithm in the RFC does not change the congestion control, the implementation intercepts congestion control in various places (e.g., frto_cwnd in tcp_ack()). The new code implements newer F-RTO RFC5682 using CA_Loss processing path. F-RTO becomes a small extension in the timeout processing and interfaces with congestion control and Eifel undo modules. It lets congestion control (module) determines how many to send independently. F-RTO only chooses what to send in order to detect spurious retranmission. If timeout is found spurious it invokes existing Eifel undo algorithms like DSACK or TCP timestamp based detection. The first patch removes all F-RTO code except the sysctl_tcp_frto is left for the new implementation. Since CA_EVENT_FRTO is removed, TCP westwood now computes ssthresh on regular timeout CA_EVENT_LOSS event. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
1 files changed, 1 insertions, 5 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index eeccf795e917..4b85e6f636c9 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -416,11 +416,7 @@ void tcp_retransmit_timer(struct sock *sk)
NET_INC_STATS_BH(sock_net(sk), mib_idx);
- if (tcp_use_frto(sk)) {
- tcp_enter_frto(sk);
- } else {
- tcp_enter_loss(sk, 0);
- }
+ tcp_enter_loss(sk, 0);
if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) {
/* Retransmission failed because of local congestion,