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Message-ID: <3c750ac3-8739-89ed-ce41-d4cde755171e@huawei.com>
Date: Wed, 13 Sep 2017 15:15:24 +0800
From: liujian <liujian56@...wei.com>
To: Eric Dumazet <eric.dumazet@...il.com>
CC: <davem@...emloft.net>, <kuznet@....inr.ac.ru>,
<yoshfuji@...ux-ipv6.org>, <edumazet@...gle.com>,
<ycheng@...gle.com>, <hkchu@...gle.com>, <netdev@...r.kernel.org>,
<weiyongjun1@...wei.com>,
wangkefeng 00227729 <wangkefeng.wang@...wei.com>
Subject: Re: [PATCH] tcp: TCP_USER_TIMEOUT can not work in tcp_probe_timer()
在 2017/9/13 14:56, liujian 写道:
>
>
> 在 2017/9/12 23:38, Eric Dumazet 写道:
>> On Tue, 2017-09-12 at 08:05 -0700, Eric Dumazet wrote:
>>> On Tue, 2017-09-12 at 14:08 +0800, liujian wrote:
>>>> Hi,
>>>>
>>>> In the scenario, tcp server side IP changed, and at that memont,
>>>> userspace application still send data continuously;
>>>> tcp_send_head(sk)'s timestamp always be refreshed.
>>>>
>>>> Here is the packetdrill script:
>>>>
>>>> 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
>>>> +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
>>>> +0 bind(3, ..., ...) = 0
>>>> +0 listen(3, 1) = 0
>>>>
>>>> +0 < S 0:0(0) win 0 <mss 1460,sackOK,nop,nop,nop,wscale 7>
>>>> +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7>
>>>>
>>>> +.1 < . 1:1(0) ack 1 win 65530
>>>> +0 accept(3, ..., ...) = 4
>>>>
>>>> +0 setsockopt(4, SOL_TCP, TCP_USER_TIMEOUT, [3000], 4) = 0
>>>> +0 write(4, ..., 24) = 24
>>>> +0 > P. 1:25(24) ack 1 win 229
>>>> +.1 < . 1:1(0) ack 25 win 65530
>>>>
>>>> //change the ipaddress
>>>> +1 `ifconfig tun0 192.168.0.10/16`
>>>>
>>>> +1 write(4, ..., 24) = 24
>>>> +1 write(4, ..., 24) = 24
>>>> +1 write(4, ..., 24) = 24
>>>> +1 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>> +3 write(4, ..., 24) = 24
>>>>
>>>> +0 `ifconfig tun0 192.168.0.1/16`
>>>> +0 < . 1:1(0) ack 1 win 1000
>>>> +0 write(4, ..., 24) = -1
>>>>
>>>>
>>>
>>> This has nothing to do with the code patch you have changed.
>>>
>>> How have you tested your patch exactly ?
>>>
> I tested the patch, it can work.
>
> [root@...alhost ~]# time ./gtests/net/packetdrill/packetdrill test.pkt
> test.pkt:24: runtime error in write call: Expected result 24 but got -1 with errno 110 (Connection timed out)
>
> real 0m5.356s
> user 0m0.026s
> sys 0m0.104s
>
> [root@...alhost ~]# ss -toenmi src :8080
> State Recv-Q Send-Q Local Address:Port Peer Address:Port
> ESTAB 0 48 192.168.0.1:8080 192.0.2.1:39559 timer:(persist,186ms,2) ino:37178 sk:6 <->
> skmem:(r0,rb369280,t0,tb87040,f1792,w2304,o0,bl0) sack cubic wscale:7,7 rto:301 backoff:2 rtt:100.253/37.643 mss:1460 cwnd:10 bytes_acked:24 segs_out:5 segs_in:3 send 1.2Mbps lastsnd:976 lastrcv:4082 lastack:3982 pacing_rate 2.3Mbps rcv_space:29200
>
>
> if change the TCP_USER_TIMEOUT to 30s, test result as below:
>
> [root@...alhost ~]# time ./gtests/net/packetdrill/packetdrill test.pkt
> test.pkt:37: runtime error in write call: Expected result 24 but got -1 with errno 110 (Connection timed out)
>
> real 0m44.362s
> user 0m0.018s
> sys 0m0.110s
>
> ESTAB 0 360 192.168.0.1:8080 192.0.2.1:47577 timer:(persist,516ms,6) ino:18806 sk:5 <->
> skmem:(r0,rb369280,t0,tb87040,f1792,w2304,o0,bl0) sack cubic wscale:7,7 rto:301 backoff:6 rtt:100.228/37.623 mss:10 bytes_acked:24 segs_out:22 segs_in:3 send 1.2Mbps lastsnd:2343 lastrcv:40450 lastack:40350 pacing_rate 2.3Mbps rcv_sp
>
>>
>> lpaa23:~# ss -toenmi src :8080
>> State Recv-Q Send-Q Local Address:Port Peer
>> Address:Port
>> ESTAB 0 144 192.168.134.161:8080
>> 192.0.2.1:51165 timer:(persist,8.262ms,5) ino:1
>> 82083 sk:3 <->
>> skmem:(r0,rb359040,t0,tb46080,f1792,w2304,o0,bl0,d0) sack cubic
>> wscale:7,8 rto:301 backoff:5 rtt:100.127/37.576
>> mss:1460 rcvmss:536 advmss:1460 cwnd:10 bytes_acked:24 segs_out:12
>> segs_in:3 data_segs_out:12 send 1.2Mbps lastsnd:1370 l
>> astrcv:13348 lastack:13248 pacing_rate 2.3Mbps delivery_rate 116.7Kbps
>> app_limited busy:11346ms rcv_space:29200 notsent:1
>> 44 minrtt:100.043userspace application still send data continuously
>>
>> This is the typical RTO timer, not zero window probe.
>>
> with the script, it is not zero window; but the code enter tcp_probe_timer.
> ->tcp_sendmsg
> -->tcp_push
> ---->__tcp_push_pending_frames
> ------>tcp_write_xmit
> -------->tcp_transmit_skb (at this function, tcp_send_head(sk)'s timestamp was be refreshed)
> ---------->ip_queue_xmit (can not find route, return -EHOSTUNREACH)
> -------->tcp_transmit_skb (send fail, do not advance send head)
> ------->tcp_check_probe_timer (reset ICSK_TIME_PROBE0 timer)
sorry, change to
->tcp_sendmsg
-->tcp_push
---->__tcp_push_pending_frames
------>tcp_write_xmit
-------->tcp_transmit_skb (at this function, tcp_send_head(sk)'s timestamp was be refreshed)
---------->ip_queue_xmit (can not find route, return -EHOSTUNREACH)
------>tcp_write_xmit (send fail, do not advance send head)
------>tcp_check_probe_timer (reset ICSK_TIME_PROBE0 timer)
> Here userspace application still send data continuously,
> it triggered ICSK_TIME_PROBE0 timer and tcp_send_head(sk)'s timestamp refresh.
>
>
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