Date: Sun, 10 Aug 2014 11:48:58 +0800 From: Niu Zhixiong <kaiaixi@gmail.com> To: Niu Zhixiong <kaiaixi@gmail.com>, Michael Tuexen <Michael.Tuexen@lurchi.franken.de>, freebsd-net@freebsd.org, Bill Yuan <bycn82@gmail.com>, John-Mark Gurney <jmg@funkthat.com> Subject: Re: A problem on TCP in High RTT Environment. Message-ID: <CAOENNMA-dwPQr53bM4rzC=1eitoi-JAB4mCGx4zybFwUC=GMNg@mail.gmail.com> In-Reply-To: <20140810033212.GL83475@funkthat.com> 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> <CAOENNMCPuiYS7LHwMfOczhZ4yisjGkpOmWzv2pcAoi9Hhzb7dw@mail.gmail.com> <20140810022350.GI83475@funkthat.com> <CAOENNMB3=FZx5kSHVPDPBTtMKbmYJ=c_XNMcuYuoLPe=6U%2Bkxg@mail.gmail.com> <CAOENNMARg36KH1Y%2B0wG8pd7sSf8XKnMf6g790_KiKaj3Mdwyjw@mail.gmail.com> <20140810033212.GL83475@funkthat.com>
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I am using Intel I350-T4 NIC. The LRO is closed by default. And by the way, when I am using KVM-based virtual machine(virtio NIC) do the exactly same test. The results are same. ifconfig igb0 igb0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 150= 0 options=3D403bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM= ,TSO4,TSO6,VLAN_HWTSO> ether a0:36:9f:38:27:d0 inet 10.0.10.3 netmask 0xffffff00 broadcast 10.0.10.255 inet6 fe80::a236:9fff:fe38:27d0%igb0 prefixlen 64 scopeid 0x1 nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> media: Ethernet autoselect (1000baseT <full-duplex>) status: active 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 11:32 AM, John-Mark Gurney <jmg@funkthat.com> wrote= : > Niu Zhixiong wrote this message on Sun, Aug 10, 2014 at 10:50 +0800: > > I am sorry that I upload a WRONG SCTP capture. But, the throughput is > same. > > SCTP is double than TCP, about 18Mbps. > > ??? > > sctp_2.pcapng.gz > > < > https://docs.google.com/file/d/0By8sTL79ob4tMlh4WDlTSndHX0k/edit?usp=3Ddr= ive_web > > > > ??? > > Ok, the owin graph is very interesting... We do have a full 2MB window > on the receiver side, but for some reason, we only ever have just under > 6k outstanding on the connection... > > So, it looks like we send for a short period of time, and then stop > sending... Do you have LRO enabled? I think it might be related to: > https://svnweb.freebsd.org/changeset/base/r256920 > > As I'm seeing >100ms gaps where the sender doesn't send any data, and > as soon as more than one ack comes in, the next segment goes out... If > we only receive a single ack, then we wait for a timeout before sending > the next segment.. > > Can you try to disable LRO on the receiving host? > > ifconfig <iface> -lro > > And see if that helps... If it does... Applying the patch, or compiling > a more recent kernel from stable/10 that is after r257367 as that is was > the date that the change was merged... > > > On Sun, Aug 10, 2014 at 10:42 AM, Niu Zhixiong <kaiaixi@gmail.com> > wrote: > > > > > I am sure that wnd is about 2MB all the time. > > > This is my latest capture, plz see Google Drive. > > > In the latest test, TCP(0s-120s) is about 9Mbps and SCTP(0s-120s) is > about > > > 18Mbps. > > > (The bandwidth(20Mbps) and delay(200ms) is set by dummynet) > > > The SCTP and TCP are tested in same environment. > > > > > > ??? > > > sctp.pcapng.gz > > > < > https://docs.google.com/file/d/0By8sTL79ob4tYl9sM2V5a19iNVU/edit?usp=3Ddr= ive_web > > > > > ?????? > > > tcp.pcapng.gz > > > < > https://docs.google.com/file/d/0By8sTL79ob4tV0NMR1FYLUQ3MWs/edit?usp=3Ddr= ive_web > > > > > ??? > > > > > > > > > > > > Regards, > > > Niu Zhixiong > > > ????????????????????????????????????????????? > > > kaiaixi@gmail.com > > > > > > > > > On Sun, Aug 10, 2014 at 10:23 AM, John-Mark Gurney <jmg@funkthat.com> > > > wrote: > > > > > >> Niu Zhixiong wrote this message on Sun, Aug 10, 2014 at 10:12 +0800: > > >> > 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 > > >> > > >> Ok, so you are getting a full 2MB in there, and w/ that, you should > > >> easily be saturating your pipe... > > >> > > >> The next thing would be to get a tcpdump, and take a look at the > > >> window size.. Wireshark has lots of neat tools to make this analysis > > >> easy... Another tool that is good is tcptrace.. It can output a > > >> variety of different graphs that will help you track down, and see > > >> what part of the system is the problem... > > >> > > >> You probably only need a few tens of seconds of the tcpdump... > > >> > > >> > 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 21:5= 1 > > >> +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 20:3= 4 > > >> +0800: > > >> > > >>>> Dear all, > > >> > > >>>> > > >> > > >>>> Last month, I send problems related to FTP/TCP in a high RT= T > > >> > > 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 is > > >> > > >>>> always slower than SCTP. But, I think it is not possible. > (Plz > > >> see the > > >> > > >>>> 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: Th= u > 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 > > >> enough > > >> > > >>> to deal w/ the higher latency... > > >> > > >>> > > >> > > >>> Also, make sure your program isn't setting the recv buffer > size > > >> as that > > >> > > >>> will disable the auto growing... > > >> > > >> I think the program sets the buffer to 2MB, which it also doe= s > for > > >> SCTP. > > >> > > >> So having both statically at the same size makes sense for th= e > > >> > > 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 se= e > 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 u= s > know > > >> > > > if the buffer is getting to 2MB or not... > > >> > > That is correct. Niu: Can you provide this? > > -- > 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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