On 09 Aug 2014, at 20:42, John-Mark Gurney <j...@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 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=400ms). >> Besides, the TCP is extremely slow. >> >> ALL BW=20Mbps, DELAY= 0 ~ 200MS, Packet LOSS = 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 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 does for SCTP. 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... Best regards Michael > > If you use netstat -a, you should be able to see the send-q on the > sender grow as necessary... > > -- > John-Mark Gurney Voice: +1 415 225 5579 > > "All that I will do, has been done, All that I have, has not." > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org" > _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
