From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [IPv6:2a0c:4d80:42:2001::664]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 84F933B29E for ; Wed, 9 Dec 2020 07:17:09 -0500 (EST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1607516228; bh=hgkZvW9GVAqCIoCGEYwpXWPKDM1rG2ObTo2scrxjItA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=xj/YR3LZXSOsw/d+Xxxzi61E30IOUQnQP038JvHZmntMU3z+uWZUpK4KA9XsS0ehi xJuHXQcsXa0/xl4zrErlg5wpIihLfhu61PP8FSftnbtAKqUQrPZhYYr0u3wx+ByvCb +d/5Mp5QsXiZTsqTGYEbgszgIr8x9latugZ3pnatqCBkUc9tzRgdMfdHljrv+VSmtE wlEltn1wY1G17MtIjBOnueejGjQb+Scz35c/csHwUlLarJrYyC/J1WaFKE9suBmN5n A8uSVl2ZEXwhR2eObWCmEwoHg3Ec1Sofs2izvORHK3b33kfxkDBXs6zOg1lWIS7C75 EJtmWhhFSvynQ== To: Sebastian Moeller Cc: Kenneth Porter , Bufferbloat Mailing List In-Reply-To: <4E613653-EF22-40A2-B194-7BA543F15DE3@gmx.de> References: <8E303BEF17675E3847CBD76C@[172.27.17.193]> <877dprp7z3.fsf@toke.dk> <472E7038-DC03-4A54-97BC-49999B78B343@gmx.de> <871rfzp6na.fsf@toke.dk> <4E613653-EF22-40A2-B194-7BA543F15DE3@gmx.de> Date: Wed, 09 Dec 2020 13:17:08 +0100 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <87v9dbnph7.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Bloat] Why you need at least 3Mbps upload to get good game performance with ~1500byte packets: Doing the math X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Dec 2020 12:17:09 -0000 Sebastian Moeller writes: > Hi Toke, > > >> On Dec 9, 2020, at 12:20, Toke H=C3=B8iland-J=C3=B8rgensen wrote: >>=20 >> Sebastian Moeller writes: >>=20 >>> Hi Toke, >>>=20 >>>=20 >>>> On Dec 9, 2020, at 11:52, Toke H=C3=B8iland-J=C3=B8rgensen via Bloat <= bloat@lists.bufferbloat.net> wrote: >>>>=20 >>>> Kenneth Porter writes: >>>>=20 >>>>> >>>>>=20 >>>>> Upstream article: >>>>>=20 >>>>> >>>>=20 >>>> Good points, but doesn't mention options to decrease the packet size >>>> (lower MTU/MSS clamping)... :) >>>=20 >>> But he is doing exactly that in the script he developed for OpenWrt ga= mes on poor links: >>=20 >> Ah, cool! May be necessary to actually decrease the interface MTU as >> well, though, since TCP MSS clamping won't work for QUIC... > > Mmmh, QUIC does pMPUd, no? IN that case a "simple" filter to drop QUIC p= ackets along a certain size might already do the trick? Maybe? But actually lowering the MTU of the interface would have the same effect, I guess? And what happens in the wild is anyone's guess, of course... ;) >> And of course, for IPv6 you can't decrease the MTU below 1280 bytes >> without breaking spec :( > > Jepp, but MSS clamping still works, except there are limits how > low OS will go, Macos will not go below ~200, and I believe > Linux also recently got increased values for min MSS to counter > some DOS issues with SACK and friends, no? That said, it is well > possible that even IPv6 might work with smaller MTUs... Sure, MSS clamping will work even for IPv6, but only for TCP... -Toke