diff options
author | Eric Dumazet <edumazet@google.com> | 2016-04-21 10:55:23 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2016-04-24 14:43:59 -0400 |
commit | 10d3be569243def8d92ac3722395ef5a59c504e6 (patch) | |
tree | ac01b70cff99ad2e59c54e80ddcd524eaa9691a8 /include/net/tcp.h | |
parent | 8cee83dd29dea4e7d27fda3b170381059f628868 (diff) | |
download | op-kernel-dev-10d3be569243def8d92ac3722395ef5a59c504e6.zip op-kernel-dev-10d3be569243def8d92ac3722395ef5a59c504e6.tar.gz |
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 'include/net/tcp.h')
-rw-r--r-- | include/net/tcp.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index c0ef054..7f2553d 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -538,8 +538,8 @@ __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, int nonagle); bool tcp_may_send_now(struct sock *sk); -int __tcp_retransmit_skb(struct sock *, struct sk_buff *); -int tcp_retransmit_skb(struct sock *, struct sk_buff *); +int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); +int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); void tcp_retransmit_timer(struct sock *sk); void tcp_xmit_retransmit_queue(struct sock *); void tcp_simple_retransmit(struct sock *); |