From owner-freebsd-net Wed Apr 21 22:19:53 1999 Delivered-To: freebsd-net@freebsd.org Received: from Meta-Bug.ppp.ucar.edu (ras36.ucar.edu [128.117.68.36]) by hub.freebsd.org (Postfix) with SMTP id 5C88315273 for ; Wed, 21 Apr 1999 22:19:16 -0700 (PDT) (envelope-from rousskov@ircache.net) Received: from localhost (rousskov@localhost) by Meta-Bug.ppp.ucar.edu (950413.SGI.8.6.12/950213.SGI.AUTOCF) via ESMTP id XAA06441; Wed, 21 Apr 1999 23:16:07 -0600 Date: Wed, 21 Apr 1999 23:16:07 -0600 From: Alex Rousskov X-Sender: rousskov@Meta-Bug To: David Greenman Cc: freebsd-net@FreeBSD.ORG Subject: Re: _Some_ acks delayed for 200 msec? In-Reply-To: <199904220503.WAA16761@implode.root.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Wed, 21 Apr 1999, David Greenman wrote: > >Now, if that is the infamous delayed ack problem, then > > - why only *some* acks are delayed? > > Probably because of timing of the response packets. It's impossible to > say with your limited, one-sided tcpdump. Response packets are coming as soon as an ack is sent or prior to that, as far as I can tell. There was a small bi-directional tcpdump in the original post. By "one-sided", do you mean a dump collected on a single [client] host, or that server responses were filtered out in the long dump that I sent? I can certainly provide more info. Just tell me what would be useful. I was afraid of posting long tcpdumps... > The Nagle algorithm doesn't know or care about "local" networks. Right. I confused Nagle with TCP_ACK_HACK (which is sort of a Nagle-like algorithm). TCP_ACK_HACK (a sysctl option in 3.1) does depend on network "locality" from our experience. > > - why disabling Nagle (TCP_NODELAY) does not help? > > It will likely have to be disabled on both sides for your application since > there appears to be a syncronous request/response involved. It was disabled on both sides. Thanks a lot, Alex. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message