Date: Sun, 10 Aug 2014 10:12:10 +0800 From: Niu Zhixiong <kaiaixi@gmail.com> To: Michael Tuexen <Michael.Tuexen@lurchi.franken.de> Cc: freebsd-net@freebsd.org, John-Mark Gurney <jmg@funkthat.com>, Bill Yuan <bycn82@gmail.com> Subject: Re: A problem on TCP in High RTT Environment. Message-ID: <CAOENNMCPuiYS7LHwMfOczhZ4yisjGkpOmWzv2pcAoi9Hhzb7dw@mail.gmail.com> In-Reply-To: <3F6BC212-4223-4AAC-8668-A27075DC55C2@lurchi.franken.de> References: <CAOENNMA_CiBDJc0kchzUbTcf_JBwTJPF=PdBAUB6FPo-KzYkeQ@mail.gmail.com> <20140809184232.GF83475@funkthat.com> <8AE1AC56-D52F-4F13-AAA3-BB96042B37DD@lurchi.franken.de> <20140809204500.GG83475@funkthat.com> <3F6BC212-4223-4AAC-8668-A27075DC55C2@lurchi.franken.de>
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Hi During the TCP4 transmission. Proto Recv-Q Send-Q Local Address Foreign Address (state) tcp4 0 2097346 10.0.10.2.13504 10.0.10.3.9000 ESTABLISHED Regards, Niu Zhixiong =EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF= =BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D=EF=BC=8D kaiaixi@gmail.com On Sun, Aug 10, 2014 at 4:58 AM, Michael Tuexen < Michael.Tuexen@lurchi.franken.de> wrote: > > On 09 Aug 2014, at 22:45, John-Mark Gurney <jmg@funkthat.com> wrote: > > > Michael Tuexen wrote this message on Sat, Aug 09, 2014 at 21:51 +0200: > >> > >> On 09 Aug 2014, at 20:42, John-Mark Gurney <jmg@funkthat.com> wrote: > >> > >>> Niu Zhixiong wrote this message on Fri, Aug 08, 2014 at 20:34 +0800: > >>>> Dear all, > >>>> > >>>> Last month, I send problems related to FTP/TCP in a high RTT > environment. > >>>> After that, I setup a simulation environment(Dummynet) to test TCP > and SCTP > >>>> in high delay environment. After finishing the test, I can see TCP i= s > >>>> always slower than SCTP. But, I think it is not possible. (Plz see t= he > >>>> figure in the attachment). When the delay is 200ms(means RTT=3D400ms= ). > >>>> Besides, the TCP is extremely slow. > >>>> > >>>> ALL BW=3D20Mbps, DELAY=3D 0 ~ 200MS, Packet LOSS =3D 0 (by dummynet) > >>>> > >>>> This is my parameters: > >>>> FreeBSD vfreetest0 10.0-RELEASE FreeBSD 10.0-RELEASE #0: Thu Aug 7 > >>>> 11:04:15 HKT 2014 > >>>> > >>>> sysctl net.inet.tcp > >>> > >>> [...] > >>> > >>>> net.inet.tcp.recvbuf_auto: 0 > >>> > >>> [...] > >>> > >>>> net.inet.tcp.sendbuf_auto: 0 > >>> > >>> Try enabling this... This should allow the buffer to grow large enou= gh > >>> to deal w/ the higher latency... > >>> > >>> Also, make sure your program isn't setting the recv buffer size as th= at > >>> will disable the auto growing... > >> I think the program sets the buffer to 2MB, which it also does for SCT= P. > >> So having both statically at the same size makes sense for the > comparison. > >> I remember that there was a bug in the combination of LRO and delayed > ACK, > >> which was fixed, but I don't remember it was fixed before 10.0... > > > > Sounds like disabling LRO and TSO would be a useful test to see if that > > improves things... But hiren said that the fix made it, so... > > > >>> If you use netstat -a, you should be able to see the send-q on the > >>> sender grow as necessary... > > > > Also, getting the send-q output while it's running would let us know > > if the buffer is getting to 2MB or not... > That is correct. Niu: Can you provide this? > > Best regards > Michael > > > > -- > > John-Mark Gurney Voice: +1 415 225 5579 > > > > "All that I will do, has been done, All that I have, has not." > > > >
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