path: root/net/ipv4/tcp_timer.c
diff options
authorEric Dumazet <edumazet@google.com>2016-04-21 10:55:23 -0700
committerDavid S. Miller <davem@davemloft.net>2016-04-24 14:43:59 -0400
commit10d3be569243def8d92ac3722395ef5a59c504e6 (patch)
treeac01b70cff99ad2e59c54e80ddcd524eaa9691a8 /net/ipv4/tcp_timer.c
parenttipc: fix stale links after re-enabling bearer (diff)
tcp-tso: do not split TSO packets at retransmit time
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>
Diffstat (limited to '')
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 49bc474f8e35..373b03e78aaa 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -404,7 +404,7 @@ void tcp_retransmit_timer(struct sock *sk)
goto out;
- tcp_retransmit_skb(sk, tcp_write_queue_head(sk));
+ tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1);
goto out_reset_timer;
@@ -436,7 +436,7 @@ void tcp_retransmit_timer(struct sock *sk)
- if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) {
+ if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1) > 0) {
/* Retransmission failed because of local congestion,
* do not backoff.