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authorNeal Cardwell <ncardwell@google.com>2013-10-21 15:40:19 -0400
committerDavid S. Miller <davem@davemloft.net>2013-10-21 18:56:23 -0400
commit02cf4ebd82ff0ac7254b88e466820a290ed8289a (patch)
tree864cf11d0c85f96e897ab42b72535f19496accda /net
parentd69e0f7ea95fef8059251325a79c004bac01f018 (diff)
downloadlinux-02cf4ebd82ff0ac7254b88e466820a290ed8289a.tar.gz
tcp: initialize passive-side sk_pacing_rate after 3WHS
For passive TCP connections, upon receiving the ACK that completes the 3WHS, make sure we set our pacing rate after we get our first RTT sample. On passive TCP connections, when we receive the ACK completing the 3WHS we do not take an RTT sample in tcp_ack(), but rather in tcp_synack_rtt_meas(). So upon receiving the ACK that completes the 3WHS, tcp_ack() leaves sk_pacing_rate at its initial value. Originally the initial sk_pacing_rate value was 0, so passive-side connections defaulted to sysctl_tcp_min_tso_segs (2 segs) in skbuffs made in the first RTT. With a default initial cwnd of 10 packets, this happened to be correct for RTTs 5ms or bigger, so it was hard to see problems in WAN or emulated WAN testing. Since 7eec4174ff ("pkt_sched: fq: fix non TCP flows pacing"), the initial sk_pacing_rate is 0xffffffff. So after that change, passive TCP connections were keeping this value (and using large numbers of segments per skbuff) until receiving an ACK for data. Signed-off-by: Neal Cardwell <ncardwell@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_input.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 53974c7c04f..a16b01b537b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5712,6 +5712,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
} else
tcp_init_metrics(sk);
+ tcp_update_pacing_rate(sk);
+
/* Prevent spurious tcp_cwnd_restart() on first data packet */
tp->lsndtime = tcp_time_stamp;