Date: Wed, 18 Oct 2006 22:31:44 -0700 (PDT) From: Moses Leslie <marmoset@malformed.org> To: freebsd-questions@freebsd.org Subject: increasing transmit speeds in WAN setting? Message-ID: <20061018222030.S11323@fincher.users.accretive-networks.net>
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Hi, We're running 6.1-R, and are having difficulty getting decent speeds as latency increases. The server is connected via gbit copper, and is gbit or better to the internet (depending on the path). For everything local, we're able to get what you'd expect (300+MBit without really any tuning). However, when the latency is 60-80ms (IE across the US), we're unable to get better than around 300KB/s. It appears to be possibly related to the tcp.inflight stuff, but disabling it or messing with some of the related sysctls doesn't appear to help much. Downloads often start quickly, but are then throttled back down to 300KB/s within 10 seconds or so. We've changed the hz (100 to 10000), the net.inet.tcp.sendspace, kern.ipc.maxsockbuf, and tried different variations on the inflight tunables, but nothing has made a positive difference of more than ~20KB/s at best. If the server is running linux (2.6 kernel with default TCP settings), we can get much better speeds, 600-1000KB/s easily. If we were going for time/distance records, we would try changing around tcp settings on the client, but we're trying to maximize performance for standard surfers who wouldn't know how to do that, so we're looking for anything that is server side only. We've been searching high and low for any tuning ideas but aren't able to find anything that's made a difference. From looking at how the congestion stuff works in the source, it appears that something like: http://www.sigusr1.org/weblog/index.php?/categories/6-Hacks might be happening here, but we're kind of stabbing in the dark. Does anyone have any tuning ideas for 6.1 in a WAN setting? Thanks, Moses
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