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tcp: Add TCP_INFO counter for packets received out-of-order

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For receive-heavy cases on the server-side, we want to track the
connection quality for individual client IPs. This counter, similar to
the existing system-wide TCPOFOQueue counter in /proc/net/netstat,
tracks out-of-order packet reception. By providing this counter in
TCP_INFO, it will allow understanding to what degree receive-heavy
sockets are experiencing out-of-order delivery and packet drops
indicating congestion.

Please note that this is similar to the counter in NetBSD TCP_INFO, and
has the same name.

Also note that we avoid increasing the size of the tcp_sock struct by
taking advantage of a hole.

Signed-off-by: Thomas Higdon <tph@fb.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Thomas Higdon 2019-09-13 23:23:34 +00:00 committed by David S. Miller
parent 40ba6a12a5
commit f9af2dbbfe
4 changed files with 7 additions and 0 deletions
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2
include/linux/tcp.h
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@ -354,6 +354,8 @@ struct tcp_sock {
#define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
#endif
u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */
/* Receiver side RTT estimation */
u32 rcv_rtt_last_tsecr;
struct {

2
include/uapi/linux/tcp.h
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@ -270,6 +270,8 @@ struct tcp_info {
__u64 tcpi_bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans */
__u32 tcpi_dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups */
__u32 tcpi_reord_seen; /* reordering events seen */
__u32 tcpi_rcv_ooopack; /* Out-of-order packets received */
};
/* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */

2
net/ipv4/tcp.c
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@ -2653,6 +2653,7 @@ int tcp_disconnect(struct sock *sk, int flags)
tp->rx_opt.saw_tstamp = 0;
tp->rx_opt.dsack = 0;
tp->rx_opt.num_sacks = 0;
tp->rcv_ooopack = 0;
/* Clean up fastopen related fields */
@ -3295,6 +3296,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
info->tcpi_bytes_retrans = tp->bytes_retrans;
info->tcpi_dsack_dups = tp->dsack_dups;
info->tcpi_reord_seen = tp->reord_seen;
info->tcpi_rcv_ooopack = tp->rcv_ooopack;
unlock_sock_fast(sk, slow);
}
EXPORT_SYMBOL_GPL(tcp_get_info);

1
net/ipv4/tcp_input.c
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@ -4555,6 +4555,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
tp->pred_flags = 0;
inet_csk_schedule_ack(sk);
tp->rcv_ooopack += max_t(u16, 1, skb_shinfo(skb)->gso_segs);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFOQUEUE);
seq = TCP_SKB_CB(skb)->seq;
end_seq = TCP_SKB_CB(skb)->end_seq;