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tcp: add stat of data packet reordering events 

Introduce a new TCP stats to record the number of reordering events seen
and expose it in both tcp_info (TCP_INFO) and opt_stats
(SOF_TIMESTAMPING_OPT_STATS).
Application can use this stats to track the frequency of the reordering
events in addition to the existing reordering stats which tracks the
magnitude of the latest reordering event.

Note: this new stats tracks reordering events triggered by ACKs, which
could often be fewer than the actual number of packets being delivered
out-of-order.

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Wang 2018-07-31 17:46:24 -07:00 committed by David S. Miller
parent 7e10b6554f
commit 7ec65372ca
5 changed files with 11 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/tcp.h
View File

@ -220,8 +220,7 @@ struct tcp_sock {
#define TCP_RACK_RECOVERY_THRESH 16
u8 reo_wnd_persist:5, /* No. of recovery since last adj */
dsack_seen:1, /* Whether DSACK seen after last adj */
advanced:1, /* mstamp advanced since last lost marking */
reord:1; /* reordering detected */
advanced:1; /* mstamp advanced since last lost marking */
} rack;
u16 advmss; /* Advertised MSS */
u8 compressed_ack;
@ -267,6 +266,7 @@ struct tcp_sock {
u8 ecn_flags; /* ECN status bits. */
u8 keepalive_probes; /* num of allowed keep alive probes */
u32 reordering; /* Packet reordering metric. */
u32 reord_seen; /* number of data packet reordering events */
u32 snd_up; /* Urgent pointer */
/*

2
include/uapi/linux/tcp.h
View File

@ -239,6 +239,7 @@ struct tcp_info {
__u64 tcpi_bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut */
__u64 tcpi_bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans */
__u32 tcpi_dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups */
__u32 tcpi_reord_seen; /* reordering events seen */
};
/* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */
@ -264,6 +265,7 @@ enum {
TCP_NLA_BYTES_SENT, /* Data bytes sent including retransmission */
TCP_NLA_BYTES_RETRANS, /* Data bytes retransmitted */
TCP_NLA_DSACK_DUPS, /* DSACK blocks received */
TCP_NLA_REORD_SEEN, /* reordering events seen */
};
/* for TCP_MD5SIG socket option */

4
net/ipv4/tcp.c
View File

@ -2597,6 +2597,7 @@ int tcp_disconnect(struct sock *sk, int flags)
tp->bytes_sent = 0;
tp->bytes_retrans = 0;
tp->dsack_dups = 0;
tp->reord_seen = 0;
/* Clean up fastopen related fields */
tcp_free_fastopen_req(tp);
@ -3207,6 +3208,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
info->tcpi_bytes_sent = tp->bytes_sent;
info->tcpi_bytes_retrans = tp->bytes_retrans;
info->tcpi_dsack_dups = tp->dsack_dups;
info->tcpi_reord_seen = tp->reord_seen;
unlock_sock_fast(sk, slow);
}
EXPORT_SYMBOL_GPL(tcp_get_info);
@ -3234,6 +3236,7 @@ static size_t tcp_opt_stats_get_size(void)
nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BYTES_SENT */
nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_BYTES_RETRANS */
nla_total_size(sizeof(u32)) + /* TCP_NLA_DSACK_DUPS */
nla_total_size(sizeof(u32)) + /* TCP_NLA_REORD_SEEN */
0;
}
@ -3286,6 +3289,7 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk)
nla_put_u64_64bit(stats, TCP_NLA_BYTES_RETRANS, tp->bytes_retrans,
TCP_NLA_PAD);
nla_put_u32(stats, TCP_NLA_DSACK_DUPS, tp->dsack_dups);
nla_put_u32(stats, TCP_NLA_REORD_SEEN, tp->reord_seen);
return stats;
}

3
net/ipv4/tcp_input.c
View File

@ -906,8 +906,8 @@ static void tcp_check_sack_reordering(struct sock *sk, const u32 low_seq,
sock_net(sk)->ipv4.sysctl_tcp_max_reordering);
}
tp->rack.reord = 1;
/* This exciting event is worth to be remembered. 8) */
tp->reord_seen++;
NET_INC_STATS(sock_net(sk),
ts ? LINUX_MIB_TCPTSREORDER : LINUX_MIB_TCPSACKREORDER);
}
@ -1871,6 +1871,7 @@ static void tcp_check_reno_reordering(struct sock *sk, const int addend)
tp->reordering = min_t(u32, tp->packets_out + addend,
sock_net(sk)->ipv4.sysctl_tcp_max_reordering);
tp->reord_seen++;
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRENOREORDER);
}

2
net/ipv4/tcp_recovery.c
View File

@ -25,7 +25,7 @@ static u32 tcp_rack_reo_wnd(const struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
if (!tp->rack.reord) {
if (!tp->reord_seen) {
/* If reordering has not been observed, be aggressive during
* the recovery or starting the recovery by DUPACK threshold.
*/