Date: Sat, 17 Oct 2009 16:22:47 -0400 From: George Neville-Neil <gnn@neville-neil.com> To: Chuck Swiger <cswiger@mac.com> Cc: Steve Dong <sdong@huawei.com>, freebsd-performance@freebsd.org Subject: Re: Comparison of FreeBSD/Linux TCP Throughput performance Message-ID: <D3018D6C-D621-4016-9895-65987D5426FF@neville-neil.com> In-Reply-To: <0D9BF9F3-FDA1-4111-9E6C-733E1FD972F5@mac.com> References: <78DB4AE8EF5F4A1EBD3992D7404B2725@china.huawei.com> <b8592ed80910150512k6d334f89s3fa308a85e19da9e@mail.gmail.com> <4831593800614E6796A45F20BA4B818E@china.huawei.com> <001301ca4e23$b96e35b0$3322c10a@china.huawei.com> <001c01ca4e24$f10f6e70$3322c10a@china.huawei.com> <20091016075336.03eb17f2.wmoran@collaborativefusion.com> <000001ca4f3c$78dc3550$6501a8c0@china.huawei.com> <0D9BF9F3-FDA1-4111-9E6C-733E1FD972F5@mac.com>
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Hi, Trying to chime in with a few pointers here. Things to check when doing a TCP benchmark on FreeBSD. In particular make sure to adjust theses: net.inet.tcp.recvbuf_max: 262144 net.inet.tcp.recvbuf_inc: 16384 net.inet.tcp.recvbuf_auto: 1 net.inet.tcp.sendbuf_max: 262144 net.inet.tcp.sendbuf_inc: 8192 net.inet.tcp.sendbuf_auto: 1 Leave the auto on, but increase the max values and you should probably also change the inc (increment) values as well. Make sure that if you increase the buffer sizes you increase your number of mbufs and clusters as well. See kern.ipc.nmbclusters, which is a kernel tunable that can be set in /boot/loader.conf . Make sure that both of the systems you're testing have the same low level hardware support such as TCP Segment Offload (TSO) and TCP Checkusm Offload are turned on. Also you might want to turn this off: net.inet.tcp.inflight.enable: 1 This page http://fasterdata.es.net/TCP-tuning/FreeBSD.html claims that it can harm high speed connections. Those are the basics to start with. A search of "Tuning FreeBSD TCP" turns up some decent pages as well. Best, George
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