From 32efcc06d2a15fa87585614d12d6c2308cc2d3f3 Mon Sep 17 00:00:00 2001
From: Abdul Kabbani <akabbani@google.com>
Date: Fri, 24 Jan 2020 16:34:02 -0500
Subject: [PATCH] tcp: export count for rehash attempts
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>
---
include/linux/tcp.h | 2 ++
include/uapi/linux/snmp.h | 2 ++
include/uapi/linux/tcp.h | 1 +
net/ipv4/proc.c | 2 ++
net/ipv4/tcp.c | 2 ++
net/ipv4/tcp_input.c | 4 +++-
net/ipv4/tcp_timer.c | 6 ++++++
7 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 4e2124607d325c..1cf73e6f85ca83 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -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 */
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 7eee233e78d274..7d91f4debc483f 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -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
};
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index d87184e673ca83..fd9eb8f6bcae37 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -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 */
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index cc90243ccf7678..2580303249e23e 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -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
};
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2857c853e2fdc6..484485ae74c26e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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;
}
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 4915de65d278df..e8b840a4767e14 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -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)
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 1097b438befe14..c3f26dcd6704ee 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -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;
--
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