Date: Thu, 16 Nov 2006 23:43:46 +0100 From: Andre Oppermann <andre@freebsd.org> To: Andre Oppermann <andre@freebsd.org> Cc: freebsd-net@freebsd.org, freebsd-current@freebsd.org Subject: Re: Automatic TCP send socker buffer sizing Message-ID: <455CE9A2.6030900@freebsd.org> In-Reply-To: <455CB311.8040301@freebsd.org> References: <455CB311.8040301@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Andre Oppermann wrote: > This is a patch adding automatic TCP send socket buffer sizing. Normally > the socket buffers are static (either derived from global defaults or set > with setsockopt) and do not adapt to real network conditions. Two things > happen: a) your socket buffers are too small and you can't reach the full > potential of the network between both hosts; b) your socket buffers are > too big and you waste a lot of kernel memory for data just sitting around. > > With automatic TCP send socket buffers we can start with a small buffer > and quickly grow it in parallel with the TCP congestion window to match > real network conditions. > > FreeBSD has a default 32K send socket buffer. This supports a maximal > transfer rate of only slightly more than 2Mbit/s on a 100ms RTT trans- > continental link. Or at 200ms just above 1Mbit/s. With TCP send buffer > auto scaling and the default values below it supports 20Mbit/s at 100ms > and 10Mbit/s at 200ms. That's an improvement of factor 10, or 1000%. > > New sysctl's are: > > net.inet.tcp.sndbuf_auto=1 (enabled) > net.inet.tcp.sndbuf_inc=8192 (8K, step size) > net.inet.tcp.sndbuf_max=262144 (256K, growth limit) > > The patch is available here: > > http://people.freebsd.org/~andre/tcp_auto_sndbuf-20061116.diff The patch was missing the changes to tcp_usrreq.c and socketvar.h. I've replaced it with an updated one. Please fetch again. -- Andre
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?455CE9A2.6030900>