Date: Sun, 01 Jan 2006 23:34:04 +1100 From: Michael Vince <mv@roq.com> To: Zongsheng Zhang <zhang@ist.osaka-u.ac.jp> Cc: freebsd-net@freebsd.org Subject: Re: tcp performance Message-ID: <43B7CC3C.4080606@roq.com> In-Reply-To: <43B11DF3.8070501@ist.osaka-u.ac.jp> References: <43B11DF3.8070501@ist.osaka-u.ac.jp>
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Zongsheng Zhang wrote: >Hi, *, > >For testing throughput of a TCP connection, the following topology is used: > Host-A ---GB Ethernet--- Dummynet ---GB Ethernet--- Host-B > >Host-A/B use FreeBSD v6.0. Sysctl parameters of Host-A/B are: >kern.ipc.nmbclusters=32768 >net.inet.tcp.inflight.enable=0 >net.inet.tcp.sendspace=2097152 # 2M >net.inet.tcp.recvspace=2097152 # 2M > >When RTT in Dummynet is set to 0ms, the throughput (A--B) is about >900Mbps. The buffer size is enough to fill a link bandwidth=800Mbps, and >RTT=20ms. However, if RTT is set to 20ms, the throughput is only about >500Mbps. > >Are there other parameters which are necessary to adjust? Does anyone >have suggestion for high throughput? > >Thanks in advance. > > > What are you following on your hosts? Release/stable or current? I only use just release or stable. For your middle router try net.inet.ip.fastforwarding or net.isr.direct but not at the same time, then try on top enabling polling. Personally I found enabling polling worked best combined with net.inet.ip.fastforwarding. Andre Oppermann claimed in a post just recently he gets best performance using just net.inet.ip.fastforwarding without polling but that might be for just -current, I am not sure. You could also try using current, but if I had to guess you already are? Regards, Mike
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