From owner-freebsd-stable Mon Nov 16 15:17:10 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id PAA03553 for freebsd-stable-outgoing; Mon, 16 Nov 1998 15:17:10 -0800 (PST) (envelope-from owner-freebsd-stable@FreeBSD.ORG) Received: from backup.af.speednet.com.au (af.speednet.com.au [202.135.206.244]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id PAA03542 for ; Mon, 16 Nov 1998 15:17:06 -0800 (PST) (envelope-from andyf@speednet.com.au) Received: from localhost (andyf@localhost) by backup.af.speednet.com.au (8.9.1/8.9.1) with ESMTP id KAA23778; Tue, 17 Nov 1998 10:14:53 +1100 (EST) X-Authentication-Warning: backup.zippynet.iol.net.au: andyf owned process doing -bs Date: Tue, 17 Nov 1998 10:14:52 +1100 (EST) From: Andy Farkas X-Sender: andyf@backup.zippynet.iol.net.au To: Marc Slemko cc: Michael Robinson , freebsd-stable@FreeBSD.ORG Subject: Re: writev() to tcp In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Mon, 16 Nov 1998, Marc Slemko wrote: > > I've noticed this very wierd thing: with a total writev buffer of 160 > > bytes, the tcp socket is sending the first 100 bytes (on a segment boundary), > > waiting for a tcp ack on the socket, and then sending the remaining 60 bytes. > > This doesn't really have anything to do with writev() in particular. There > is a bug in the TCP code where a packet bigger than a single mbuf (MLEN == > 108 bytes) but not big enough for a mbuf cluster (MINCLSIZE == 204 bytes) > ends up being put into two mbufs that end up being put on the wire in two > parts. There should be some messages about it in the archives. There are > various fixes, but none has been made yet. > > Disabling nagle can work around some of the bad interactions between nagle > and delayed ack in this case, but isn't a great solution in general. > There is mention of this problem in the Squid FAQ at http://squid.nlanr.net/Squid/FAQ/FAQ-14.html#ss14.2 It suggests two workarounds ... -- :{ andyf@speednet.com.au Andy Farkas System Administrator Speed Internet Services http://www.speednet.com.au/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message