From owner-freebsd-net Tue Oct 15 18:53:44 2002 Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 14D9B37B408 for ; Tue, 15 Oct 2002 18:53:43 -0700 (PDT) Received: from carp.icir.org (carp.icir.org [192.150.187.71]) by mx1.FreeBSD.org (Postfix) with ESMTP id E4EF043E9E for ; Tue, 15 Oct 2002 18:53:39 -0700 (PDT) (envelope-from rizzo@carp.icir.org) Received: from carp.icir.org (localhost [127.0.0.1]) by carp.icir.org (8.12.3/8.12.3) with ESMTP id g9G1rcpJ029422; Tue, 15 Oct 2002 18:53:38 -0700 (PDT) (envelope-from rizzo@carp.icir.org) Received: (from rizzo@localhost) by carp.icir.org (8.12.3/8.12.3/Submit) id g9G1rcj6029421; Tue, 15 Oct 2002 18:53:38 -0700 (PDT) (envelope-from rizzo) Date: Tue, 15 Oct 2002 18:53:38 -0700 From: Luigi Rizzo To: Mike Silbersack Cc: Paul Herman , Lars Eggert , Steve Francis , Kirill Ponomarew , freebsd-net@FreeBSD.ORG Subject: Re: delayed ACK Message-ID: <20021015185338.A29388@carp.icir.org> References: <20021015183044.A29061@carp.icir.org> <20021015204614.L21041-100000@patrocles.silby.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20021015204614.L21041-100000@patrocles.silby.com>; from silby@silby.com on Tue, Oct 15, 2002 at 08:52:49PM -0500 Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Tue, Oct 15, 2002 at 08:52:49PM -0500, Mike Silbersack wrote: ... > NetBSD introduced a "fix" for this recently, it seems sorta hackish, but > maybe we need to do something similar. this helps you if the other side has delayed acks, but halves the throughput if you are being window limited and the other side does not use delayed acks (can you force immediate acks by setting the PUSH flag in the tcp header ?) cheers luigi > > http://cvsweb.netbsd.org/bsdweb.cgi/syssrc/sys/netinet/tcp_output.c.diff?r1=1.84&r2=1.85 > > Revision 1.85 / (download) - annotate - [select for diffs], Tue Aug 20 > 16:29:42 2002 UTC (8 weeks ago) by thorpej > Branch: MAIN > CVS Tags: gehenna-devsw-base > Changes since 1.84: +18 -4 lines > Diff to previous 1.84 (colored) > > Never send more than half a socket buffer of data. This insures that > we can always keep 2 packets on the wire, no matter what SO_SNDBUF is, > and therefore ACKs will never be delayed unless we run out of data to > transmit. The problem is quite easy to tickle when the MTU of the > outgoing interface is larger than the socket buffer size (e.g. loopback). > > Fix from Charles Hannum. > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message