| Message ID | 1537732141-22468-1-git-send-email-laoar.shao@gmail.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net-next] tcp: expose sk_state in tcp_retransmit_skb tracepoint | expand |
On 09/23/2018 12:49 PM, Yafang Shao wrote: > With sk_state, we can know whether this connection is in SYN_SENT state > or ESTBLISHED state. > The reason to distinguish between these two scenario is that the > retransmission in ESTABLISHED state always mean network congestion while > in SYN_SENT state it always mean server issue, i.e. the syn packet is > dropped due to syn backlog queue full. You mean, a packet drop on the remote peer ? It could also be a packet drop in the network. Your patch is good, but changelog is quite misleading.
On Mon, Sep 24, 2018 at 5:42 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > > > On 09/23/2018 12:49 PM, Yafang Shao wrote: >> With sk_state, we can know whether this connection is in SYN_SENT state >> or ESTBLISHED state. >> The reason to distinguish between these two scenario is that the >> retransmission in ESTABLISHED state always mean network congestion while >> in SYN_SENT state it always mean server issue, i.e. the syn packet is >> dropped due to syn backlog queue full. > > You mean, a packet drop on the remote peer ? > Yes, I mean drop on the remote peer. > It could also be a packet drop in the network. > Yes of course. > Your patch is good, but changelog is quite misleading. Will modify the changelog. Thanks Yafang
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h index ac55b32..2bc9960 100644 --- a/include/trace/events/tcp.h +++ b/include/trace/events/tcp.h @@ -56,6 +56,7 @@ TP_STRUCT__entry( __field(const void *, skbaddr) __field(const void *, skaddr) + __field(int, state) __field(__u16, sport) __field(__u16, dport) __array(__u8, saddr, 4) @@ -70,6 +71,7 @@ __entry->skbaddr = skb; __entry->skaddr = sk; + __entry->state = sk->sk_state; __entry->sport = ntohs(inet->inet_sport); __entry->dport = ntohs(inet->inet_dport); @@ -84,9 +86,10 @@ sk->sk_v6_rcv_saddr, sk->sk_v6_daddr); ), - TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c", + TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c state=%s\n", __entry->sport, __entry->dport, __entry->saddr, __entry->daddr, - __entry->saddr_v6, __entry->daddr_v6) + __entry->saddr_v6, __entry->daddr_v6, + show_tcp_state_name(__entry->state)) ); DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb,
With sk_state, we can know whether this connection is in SYN_SENT state or ESTBLISHED state. The reason to distinguish between these two scenario is that the retransmission in ESTABLISHED state always mean network congestion while in SYN_SENT state it always mean server issue, i.e. the syn packet is dropped due to syn backlog queue full. PS: SYNACK retransmission is traced in tcp_retransmit_synack tracepoint. Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- include/trace/events/tcp.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)