From owner-freebsd-hardware Wed Jul 3 9: 6:48 2002 Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BBAE037B405 for ; Wed, 3 Jul 2002 09:06:38 -0700 (PDT) Received: from wall.polstra.com (wall-gw.polstra.com [206.213.73.130]) by mx1.FreeBSD.org (Postfix) with ESMTP id BEFB843E09 for ; Wed, 3 Jul 2002 09:06:37 -0700 (PDT) (envelope-from jdp@polstra.com) Received: from vashon.polstra.com (vashon.polstra.com [206.213.73.13]) by wall.polstra.com (8.11.3/8.11.3) with ESMTP id g63G6aT52630; Wed, 3 Jul 2002 09:06:37 -0700 (PDT) (envelope-from jdp@vashon.polstra.com) Received: (from jdp@localhost) by vashon.polstra.com (8.12.4/8.12.4/Submit) id g5TJMW1h007693; Sat, 29 Jun 2002 12:22:32 -0700 (PDT) Date: Sat, 29 Jun 2002 12:22:32 -0700 (PDT) Message-Id: <200206291922.g5TJMW1h007693@vashon.polstra.com> To: hardware@freebsd.org From: John Polstra Cc: jack_zhangcl@hotmail.com Subject: Re: wscale issue on netperf testing In-Reply-To: References: Organization: Polstra & Co., Seattle, WA Sender: owner-freebsd-hardware@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org In article , zhang jack wrote: > Hi, > > I am testing giga bits NICs with netperf,two machine have the same install, > but when I start netperf,using tcpdump to listen,the wscale is different. > > giga# tcpdump -vv -n -i em0 -c 100 > tcpdump: listening on em0 > 19:28:35.946808 10.0.0.1.49187 > 10.0.0.2.12865: S [tcp sum ok] > 3414289560:3414289560(0) win 65535 4,nop,nop,timestamp 336910 0> (ttl 64, id 12226, len 60) > 19:28:35.946877 10.0.0.2.12865 > 10.0.0.1.49187: S [bad tcp cksum 751c!] > 2862099494:2862099494(0) ack 3414289561 win 57344 0,nop,nop,timestamp 346195 336910> (ttl 64, id 27150, len 60) Check again, and I think you will discover that the two machines do not have the same install. In FreeBSD 4-stable the default receive window was reduced from 64k to 57k on 7 June 2002. One of your machines has that change, and the other one does not have it. Here is the explanation of the change from the commit log message: revision 1.51.2.13 date: 2002/06/07 20:23:44; author: obrien; state: Exp; lines: +1 -1 IPfiler has problems with its keep state when the windows size is 64k. So reduce it to 57k for now. It should remain 64k in -CURRENT so we can force a fix in broken software. There is nice explanation in the PR about the environment in which the bug happens. Approved by: murray PR: 34801 Submitted by: AMAKAWA Shuhei You can easily change the receive window with the sysctl variable "net.inet.tcp.recvspace". John -- John Polstra John D. Polstra & Co., Inc. Seattle, Washington USA "Disappointment is a good sign of basic intelligence." -- Chögyam Trungpa To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message