From owner-freebsd-net Sun Jun 18 12:39:23 2000 Delivered-To: freebsd-net@freebsd.org Received: from implode.root.com (root.com [209.102.106.178]) by hub.freebsd.org (Postfix) with ESMTP id 2FB6A37B997 for ; Sun, 18 Jun 2000 12:39:19 -0700 (PDT) (envelope-from dg@implode.root.com) Received: from implode.root.com (localhost [127.0.0.1]) by implode.root.com (8.8.8/8.8.5) with ESMTP id MAA15444; Sun, 18 Jun 2000 12:30:24 -0700 (PDT) Message-Id: <200006181930.MAA15444@implode.root.com> To: "Richard A. Steenbergen" Cc: freebsd-net@FreeBSD.ORG Subject: Re: Auto-scaling socket buffers In-reply-to: Your message of "Sun, 18 Jun 2000 15:03:28 EDT." From: David Greenman Reply-To: dg@root.com Date: Sun, 18 Jun 2000 12:30:24 -0700 Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org >IDEA: > >Which leads to my idea. Automatically scale the socket buffer when the TCP >window is exausted and the reason it cannot be extended is the sockbuf. >This would allow the default recvspace/sendspace to be set to something >like 4k, but still allow performance sockets to quickly scale upwards to a >set limit, to achieve maximium thruput. This idea sounds familiar and I think it has been suggested before. It does seem like a good idea. One concern that I have is the case of a saturated local (ethernet) circuit, causing the delay to increase due to buffering in the network device driver and perhaps in the nearby upstream switches. Since the problem is lack of bandwidth that is causing the delay to increase, it seems that the new algorithm would behave badly - increasing the socket buffer space on all connections needlessly. In other words, it might be a bad assumption that delay is caused by speed of light lag when it might instead be caused by network congestion which isn't helped by increasing the amount of buffering. -DG David Greenman Co-founder, The FreeBSD Project - http://www.freebsd.org Manufacturer of high-performance Internet servers - 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