Date: Fri, 11 Apr 2003 09:22:47 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: bj@dc.luth.se Cc: David Gilbert <dgilbert@velocet.ca> Subject: Re: tcp_output starving -- is due to mbuf get delay? Message-ID: <3E96EBD7.5CA4C171@mindspring.com> References: <200304111407.h3BE7hKl086838@dc.luth.se>
next in thread | previous in thread | raw e-mail | index | archive | help
Borje Josefsson wrote: > I should add that I have tried with MTU 1500 also. Using NetBSD as sender > works fine (just a little bit higher CPU load). When we tried MTU1500 with > FreeBSD as sender, we got even lower performance. > > Somebody else in this thread said that he had got full GE speed between > two FreeBSD boxes connected back-to-back. I don't question that, but that > doesn't prove anything. The problem arises when You are trying to do this > long-distance and have to handle a large mbuf queue. The boxes were not connected "back to back", they were connected through three Gigabit switches and a VLAN trunk. But they were in a lab, yes. I'd be happy to try long distance for you, and even go so far as to fix the problem for you, if you are willing to drop 10GBit fiber to my house. 8-) 8-). As far as a large mbuf queue, one thing that's an obvious difference is SACK support; however, this can not be the problem, since the NetBSD->FreeBSD speed is unafected (supposedly). What is the FreeBSD->NetBSD speed? Some knobs to try on FreeBSD: net.inet.ip.intr_queue_maxlen -> 300 net.inet.ip.check_interface -> 0 net.inet.tcp.rfc1323 -> 0 net.inet.tcp.inflight_enable -> 1 net.inet.tcp.inflight_debug -> 0 net.inet.tcp.delayed_ack -> 0 net.inet.tcp.newreno -> 0 net.inet.tcp.slowstart_flightsize -> 4 net.inet.tcp.msl -> 1000 net.inet.tcp.always_keepalive -> 0 net.inet.tcp.sendspace -> 65536 (on sender) Don't try them all at once and expect magic; you will probably need some combination. Also, try recompiling your kernel *without* IPSEC support. -- Terry
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3E96EBD7.5CA4C171>