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tcp: export count for rehash attempts

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Using IPv6 flow-label to swiftly route around avoid congested or
disconnected network path can greatly improve TCP reliability.

This patch adds SNMP counters and a OPT_STATS counter to track both
host-level and connection-level statistics. Network administrators
can use these counters to evaluate the impact of this new ability better.

Export count for rehash attempts to
1) two SNMP counters: TcpTimeoutRehash (rehash due to timeouts),
   and TcpDuplicateDataRehash (rehash due to receiving duplicate
   packets)
2) Timestamping API SOF_TIMESTAMPING_OPT_STATS.

Signed-off-by: Abdul Kabbani <akabbani@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Kevin(Yudong) Yang <yyd@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Abdul Kabbani 2020-01-24 16:34:02 -05:00 committed by David S. Miller
parent 6efca894e9
commit 32efcc06d2
7 changed files with 18 additions and 1 deletions
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2
include/linux/tcp.h
View file

@ -386,6 +386,8 @@ struct tcp_sock {
#define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
#endif
u16 timeout_rehash; /* Timeout-triggered rehash attempts */
u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */
/* Receiver side RTT estimation */

2
include/uapi/linux/snmp.h
View file

@ -285,6 +285,8 @@ enum
LINUX_MIB_TCPRCVQDROP, /* TCPRcvQDrop */
LINUX_MIB_TCPWQUEUETOOBIG, /* TCPWqueueTooBig */
LINUX_MIB_TCPFASTOPENPASSIVEALTKEY, /* TCPFastOpenPassiveAltKey */
LINUX_MIB_TCPTIMEOUTREHASH, /* TCPTimeoutRehash */
LINUX_MIB_TCPDUPLICATEDATAREHASH, /* TCPDuplicateDataRehash */
__LINUX_MIB_MAX
};

1
include/uapi/linux/tcp.h
View file

@ -311,6 +311,7 @@ enum {
TCP_NLA_DSACK_DUPS, /* DSACK blocks received */
TCP_NLA_REORD_SEEN, /* reordering events seen */
TCP_NLA_SRTT, /* smoothed RTT in usecs */
TCP_NLA_TIMEOUT_REHASH, /* Timeout-triggered rehash attempts */
};
/* for TCP_MD5SIG socket option */

2
net/ipv4/proc.c
View file

@ -289,6 +289,8 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPRcvQDrop", LINUX_MIB_TCPRCVQDROP),
SNMP_MIB_ITEM("TCPWqueueTooBig", LINUX_MIB_TCPWQUEUETOOBIG),
SNMP_MIB_ITEM("TCPFastOpenPassiveAltKey", LINUX_MIB_TCPFASTOPENPASSIVEALTKEY),
SNMP_MIB_ITEM("TcpTimeoutRehash", LINUX_MIB_TCPTIMEOUTREHASH),
SNMP_MIB_ITEM("TcpDuplicateDataRehash", LINUX_MIB_TCPDUPLICATEDATAREHASH),
SNMP_MIB_SENTINEL
};

2
net/ipv4/tcp.c
View file

@ -3337,6 +3337,7 @@ static size_t tcp_opt_stats_get_size(void)
nla_total_size(sizeof(u32)) + /* TCP_NLA_DSACK_DUPS */
nla_total_size(sizeof(u32)) + /* TCP_NLA_REORD_SEEN */
nla_total_size(sizeof(u32)) + /* TCP_NLA_SRTT */
nla_total_size(sizeof(u16)) + /* TCP_NLA_TIMEOUT_REHASH */
0;
}
@ -3391,6 +3392,7 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk)
nla_put_u32(stats, TCP_NLA_DSACK_DUPS, tp->dsack_dups);
nla_put_u32(stats, TCP_NLA_REORD_SEEN, tp->reord_seen);
nla_put_u32(stats, TCP_NLA_SRTT, tp->srtt_us >> 3);
nla_put_u16(stats, TCP_NLA_TIMEOUT_REHASH, tp->timeout_rehash);
return stats;
}

4
net/ipv4/tcp_input.c
View file

@ -4271,8 +4271,10 @@ static void tcp_rcv_spurious_retrans(struct sock *sk, const struct sk_buff *skb)
* The receiver remembers and reflects via DSACKs. Leverage the
* DSACK state and change the txhash to re-route speculatively.
*/
if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq)
if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq) {
sk_rethink_txhash(sk);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDUPLICATEDATAREHASH);
}
}
static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb)

6
net/ipv4/tcp_timer.c
View file

@ -223,6 +223,9 @@ static int tcp_write_timeout(struct sock *sk)
dst_negative_advice(sk);
} else {
sk_rethink_txhash(sk);
tp->timeout_rehash++;
__NET_INC_STATS(sock_net(sk),
LINUX_MIB_TCPTIMEOUTREHASH);
}
retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
expired = icsk->icsk_retransmits >= retry_until;
@ -234,6 +237,9 @@ static int tcp_write_timeout(struct sock *sk)
dst_negative_advice(sk);
} else {
sk_rethink_txhash(sk);
tp->timeout_rehash++;
__NET_INC_STATS(sock_net(sk),
LINUX_MIB_TCPTIMEOUTREHASH);
}
retry_until = net->ipv4.sysctl_tcp_retries2;