From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [52.28.52.200]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id A9AC03B2A4 for ; Thu, 6 Apr 2017 11:58:28 -0400 (EDT) From: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1491494307; bh=NMX5LENoPH8o5RQeGEwDro7xrraqBmbpuQ6MM1U77eg=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=PqP21yti5JuV7lr4yE7RGD6TwspbnEh1PL7IPDx2V61hwfyte10xh4Ny63fOzfANL S5QsdKnHNdOLePVYKxMoW7e0cw/GQGpIdfA76aU024HySNhuhqMr0+VDgGnKNQMUUj KsFpAbLlhrznuT7JKb+eMg04YhCIFlIvUuZ8Pgxkn5h5c0IjcCpK23TP8RAYPTVzNV Rm8k0mzfv27v+z2JsieyTdVlwtUL2t/yGwgFINJCIVBgAQ1uw88VG39og1AxeEkq6y y/VRv3knRNnvq45OuGmuEiBixNVmKhKWGDpDxAAjN/EDd9E1NcL0jaZXITMkrjV3R0 cXjvSWqF8X3Uw== To: Eric Dumazet Cc: make-wifi-fast@lists.bufferbloat.net, linux-wireless@vger.kernel.org References: <20170405161810.30671-1-toke@toke.dk> <20170406093826.16626-1-toke@toke.dk> <1491475915.10124.75.camel@edumazet-glaptop3.roam.corp.google.com> Date: Thu, 06 Apr 2017 17:58:25 +0200 In-Reply-To: <1491475915.10124.75.camel@edumazet-glaptop3.roam.corp.google.com> (Eric Dumazet's message of "Thu, 06 Apr 2017 03:51:55 -0700") X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <87efx5ply6.fsf@alrua-kau> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Make-wifi-fast] [PATCH v3] mac80211: Dynamically set CoDel parameters per station X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Apr 2017 15:58:28 -0000 Eric Dumazet writes: > On Thu, 2017-04-06 at 11:38 +0200, Toke H=C3=B8iland-J=C3=B8rgensen wrote: > >> + >> + if (thr && thr < STA_SLOW_THRESHOLD * sta->local->num_sta) { >> + sta->cparams.target =3D MS2TIME(50); >> + sta->cparams.interval =3D MS2TIME(300); >> + sta->cparams.ecn =3D false; >> + } else { >> + sta->cparams.target =3D MS2TIME(20); >> + sta->cparams.interval =3D MS2TIME(100); >> + sta->cparams.ecn =3D true; >> + } >> +} > > Why ECN is flipped on/off like that ? The reasoning is that at really low bandwidths we're better off dropping the packet and getting potentially latency-sensitive data queued behind it through (see Dave's various rants with the topic "Packets have mass"). > ECN really should be an admin choice. Well, the trouble is that the mac80211 queues don't really have an admin interface currently. So it'll always use ECN (before this change). > Also, this change in parameters looks suspect to me, adding a bimodal > behavior. I would consult Kathleen and Van on this possibility. Yeah, I agree that it's somewhat of a hack from a theoretical point of view. I've also been experimenting with Kathy's recommended way of dealing with bursty MACs (turning off CoDel when there's less than an MTU's worth of data left), but have not had a lot of success with it. Guess I can go back and try some variants on that, unless someone else has better ideas? -Toke