Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751333AbVIBOsJ (ORCPT ); Fri, 2 Sep 2005 10:48:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751320AbVIBOsJ (ORCPT ); Fri, 2 Sep 2005 10:48:09 -0400 Received: from mailer1.psc.edu ([128.182.58.100]:3551 "EHLO mailer1.psc.edu") by vger.kernel.org with ESMTP id S1751224AbVIBOsI (ORCPT ); Fri, 2 Sep 2005 10:48:08 -0400 In-Reply-To: References: <20050901.154300.118239765.davem@davemloft.net> <2d02c76a84655d212634a91002b3eccd@psc.edu> <20050901.232823.123760177.davem@davemloft.net> <6064b8272aa4562242eb60eb75c7cdae@psc.edu> Mime-Version: 1.0 (Apple Message framework v622) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <002cb4586f9d008438e81da96e5cecd0@psc.edu> Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , linux-net@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org From: John Heffner Subject: Re: Possible BUG in IPv4 TCP window handling, all recent 2.4.x/2.6.x kernels Date: Fri, 2 Sep 2005 10:48:01 -0400 To: lists@limebrokerage.com X-Mailer: Apple Mail (2.622) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1313 Lines: 28 On Sep 2, 2005, at 10:33 AM, lists@limebrokerage.com wrote: > On Fri, 2 Sep 2005, John Heffner wrote: > >> Have you tried increasing the size of the receive buffer yet? > > Actually, I just did. I changed rmem_max and rmem_default to 4MB and > tcp_rmem to "64k 4MB 4MB". It did seem to help, but I'm wondering if > that's simply because it has a _lot_ of memory now to leak before it > starts eating up into the window size. If it is window clamping, then you should be asymptotically approaching a ratio between receive buffer and window that corresponds (with a fudge factor) to the ratio between TCP segment data size and allocated packet size. If you make the receive buffer large enough, then the clamped window should still end up big enough. Also, since you have "real time" data, a larger receive buffer should probably be adequate to eliminate this problem, since it only occurs when the receiving application falls behind for a while, and a bigger receive buffer allows it to fall behind more without triggering the window clamping. -John - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/