Date: Thu, 31 May 2007 9:54:36 -0500 From: Nicolas Gieczewski <nicolas@nixsoftware.com> To: Pang <freebsd@laws.ms> Cc: freebsd-net@freebsd.org, freebsd-questions@freebsd.org Subject: Re: Download speed and TCPIP window sizing Message-ID: <37f6bd601e453b39a3f70c0e95be3876@75.126.162.136> In-Reply-To: <465ED66F.30902@laws.ms> References: <465ED66F.30902@laws.ms>
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On Thu, 31 May 2007 22:06:39 +0800, Pang <freebsd@laws.ms> wrote: > Recently, I have leased a rack in Asianetcom and some bandwidth. > However, the speed for my curcuit is substantially slower than my > provider's company site. > [...] > *This server is using FreeBSD 6.2 patch 4 with Apache in the port tree. > The kernel is custom built but I haven't made any modification in sysctl > > I have asked many techs in Asianetcom and they blamed on TCPIP window > sizing. I used to have the same problem with my FreeBSD dedicated servers in the U.S. when I was living in South America with a latency of ~200 ms. Given identical hardware and connectivity, I could max out my download speed when downloading from a server running Linux, but would get no more than 100-150 KB/s when downloading from an otherwise identical FreeBSD box. The solution was to increase the size of the TCP send window on the FreeBSD server to about 128 KB--the default of 32 KB turned out to be way too small. # sysctl net.inet.tcp.sendspace=131072 After modifying this value, you need to restart any processes (e.g. Apache) that you want to take advantage of the change. Hope it helps.
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