From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <toke@toke.dk>
Received: from mail.toke.dk (mail.toke.dk [52.28.52.200])
 (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by lists.bufferbloat.net (Postfix) with ESMTPS id 1474C3BA8E
 for <cake@lists.bufferbloat.net>; Fri, 24 Nov 2017 06:21:33 -0500 (EST)
From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023;
 t=1511522490; bh=4Nx7/7QUSwgtBhxazMWqA3tChP6kBEjLBjoTEiEFk4o=;
 h=From:To:Cc:Subject:In-Reply-To:References:Date:From;
 b=SnuvszoqZtFPw+yvjOWeFkys2Otk601hG90LSOTQV1XkFioHo3yMiHXTMfHiGeFhP
 J/xRl/a7Z7HrgFQxXHf6dyz4r3YEIwhbuznniWhcNWISvf5w86pfyaq9U8+wGRP9mE
 2ZDo7M+dVtXdjg0zk4jjthhHdklpx5xsT/fbctwwiMWZP2p4+LSJKCmmo+LIAAwx7l
 DVkO+wUx4lo+xi6LRA9wNCeyWjh1H6KVMMXe3l0zT1nM1jx+f/VSFussaUIfkVp6KS
 xYp2WBy73pFi1SxqGIuzZ6A6Etsx6LR3NwYRXGZokwiLRry45bPQEyYvDYHfUJ/5bg
 zn1Fx1MslcGwA==
To: Dave Taht <dave@taht.net>, Pete Heist <peteheist@gmail.com>
Cc: Cake List <cake@lists.bufferbloat.net>
In-Reply-To: <87tvxlvsex.fsf@nemesis.taht.net>
References: <71FB183D-F848-4513-A6F6-D03FD0F10769@gmail.com>
 <CAJq5cE08yhPxOJwCBbHFQiQ1Hp4_Zff2f7Oia+a5S=tdNZBJNg@mail.gmail.com>
 <52C2B216-220C-4C17-882C-9994867E86BB@gmail.com>
 <87tvxlvsex.fsf@nemesis.taht.net>
Date: Fri, 24 Nov 2017 12:21:30 +0100
X-Clacks-Overhead: GNU Terry Pratchett
Message-ID: <87609zapmt.fsf@toke.dk>
MIME-Version: 1.0
Content-Type: text/plain
Subject: Re: [Cake] lan keyword affects host fairness
X-BeenThere: cake@lists.bufferbloat.net
X-Mailman-Version: 2.1.20
Precedence: list
List-Id: Cake - FQ_codel the next generation <cake.lists.bufferbloat.net>
List-Unsubscribe: <https://lists.bufferbloat.net/options/cake>,
 <mailto:cake-request@lists.bufferbloat.net?subject=unsubscribe>
List-Archive: <https://lists.bufferbloat.net/pipermail/cake>
List-Post: <mailto:cake@lists.bufferbloat.net>
List-Help: <mailto:cake-request@lists.bufferbloat.net?subject=help>
List-Subscribe: <https://lists.bufferbloat.net/listinfo/cake>,
 <mailto:cake-request@lists.bufferbloat.net?subject=subscribe>
X-List-Received-Date: Fri, 24 Nov 2017 11:21:33 -0000

Dave Taht <dave@taht.net> writes:

> Pete Heist <peteheist@gmail.com> writes:
>
>>     On Nov 23, 2017, at 10:44 AM, Jonathan Morton <chromatix99@gmail.com> wrote:
>>     
>>     This is most likely an interaction of the AQM with Linux' scheduling
>>     latency.
>>
>>     At the 'lan' setting, the time comstants are similar in magnitude to the
>>     delays induced by Linux itself, so congestion might be signalled
>>     prematurely. The flows will then become sparse and total throughput reduced,
>>     leaving little or no back-pressure for the fairness logic to work against.
>
> Agreed. 
>
> man page add:
>
> At the 'lan' setting(1ms), the time constants are similar in magnitude
> to the jitter in the Linux kernel itself, so congestion might be
> signalled prematurely. The flows will then become sparse and total
> throughput reduced, leaving little or no back-pressure for the fairness
> logic to work against. Use the "metro" setting for local lans unless you
> have a custom kernel.

Erm, doesn't this make the 'lan' keyword pretty much useless? So why not
just remove it? Or redefine it to something that actually works? 3ms?

-Toke