Date: Mon, 01 Jul 2002 10:40:17 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: hawkeyd@visi.com Cc: DougB@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG Subject: Re: ftp and mail much slower into fbsd 4.4 vs and old BSDi Message-ID: <3D209401.DA05586D@mindspring.com> References: <5.1.0.14.2.20020629235459.031daf28_mail.Go2France.com@ns.sol.net> <3D1EB35C.70F64275_FreeBSD.org@ns.sol.net> <200207011600.g61G0RW06589@sheol.localdomain> <3D2089D5.89D0CE7D@mindspring.com> <20020701121324.A6798@sheol.localdomain>
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D J Hawkey Jr wrote: > > If you turn it off, you rat all your firends out in the Prisoner's > > Dilemma. > > > > Congestion control protocols only work if everyone participates. > > > > All "Reno TCP" implementations include TCP Fast Retransmit and Fast > > Recovery algorithms [RFC2581]... > > > > [SNIP] > > > > ...THat's the PSC "nutshell" description of NewReno. > > OK. Thanks, Terry. > > I'm guessing that the suggestion to turn it off (the original thread) is > valid enough, as all machines referred to were on the same network, else > why wouldn't the above still hold true? Or is it a matter of FTP and/or > SMTP (specifically, sendmail) not playing nice with newreno? No. Disabling congestion control is a bad thing. There are some known bugs in the FreeBSD implementation; see the Matt Dillon postings on the subject; he posted a couple of patches that would work around (but not fix) the problems with the FreeBSD code. I thought they had been checked in, so as long as you are running a recent release, it should not be an issue. If you are hitting the problem, then you are hitting congestion, or it would not be triggering. Butting in front of other people in line at the movie theater seems like a good idea: you get your tickets and popcorn faster, and you always get a nice seat. Until everyone else starts to do the same thing. Then it becomes a fist-fight. I personally like TCP Rate Halving (Hoe, et. al.) as a congestion solution: half-rate ACK-based self-pacing during congestion. The patches for NetBSD are up on the CMU PSC site, and are easily portable to FreeBSD. In any case, you need to read Dillon's postings and the other references (particularly, RFC-2581) so that you understand what it is that you are turning off. Search for "Reno" in the FreeBSD-current archives to find the thread in which the comments were posted. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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