Date: Sun, 05 Nov 2000 14:57:28 -0800 From: David Greenman <dg@root.com> To: "Richard A. Steenbergen" <ras@e-gerbil.net> Cc: freebsd-net@freebsd.org Subject: Re: tcp sendspace/recvspace Message-ID: <200011052257.OAA24410@implode.root.com> In-Reply-To: Your message of "Sun, 05 Nov 2000 17:29:14 EST." <Pine.BSF.4.21.0011051715520.306-100000@overlord.e-gerbil.net>
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>BTW a blanket 32k in both directions, while not an outright bad idea, is >not optimal and probably overly wasteful. In most cases you can achieve >your increased thruput by setting the recv buffer higher without needing >to make the sendbuf match, but the numbers you're looking for are probably >closet to 65535 without rfc1323 window scaling or at least 256k with, in >order to get optimal thruput. You can obviously see problems coming from >this. Among other things its just plain stupid, not every connection needs >the memory it just needs the potential for the memory for any given >connection at any given time, and you open yourself to mbuf exhaustion and >various forms of attacks by trying to achieve that with blanket numbers. Uh, the negotiated window maximum is the lower of the receiver's advertised window and the sender's congestion window, so both sides must cooperate for a larger window to be used. Since FreeBSD is used as both a client and server platform, I feel it is important to increase both recvspace and sendspace. Overall I like the idea of a dynamically scaling these, but I'm talking about the "right now" and not the "next year some time, maybe". I am concerned about the increased memory use in some applications, but memory is cheap these days and getting cheaper. Really the only issue I see is that some people may not be prepared to tune there kernel configs to allow for the increased network buffer use. -DG David Greenman Co-founder, The FreeBSD Project - http://www.freebsd.org President, TeraSolutions, Inc. - http://www.terasolutions.com Pave the road of life with opportunities. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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