From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 0D2AE3B29E for ; Wed, 25 Jul 2018 06:07:39 -0400 (EDT) Received: from [172.16.11.53] ([134.76.241.253]) by mail.gmx.com (mrgmx002 [212.227.17.190]) with ESMTPSA (Nemesis) id 0MXZw6-1fWhhE3Pbq-00WZx4; Wed, 25 Jul 2018 12:07:30 +0200 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Sebastian Moeller In-Reply-To: <87effr3a72.fsf@toke.dk> Date: Wed, 25 Jul 2018 12:07:28 +0200 Cc: =?utf-8?Q?Dave_T=C3=A4ht?= , Cake List Content-Transfer-Encoding: quoted-printable Message-Id: <6495D4D7-0920-43C7-A92E-3027102E723D@gmx.de> References: <87effr3a72.fsf@toke.dk> To: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Mailer: Apple Mail (2.3445.9.1) X-Provags-ID: V03:K1:v2wwSQLLrwb6iNj5xuurOFoKN+AFmrvmSj7axhCok6oHymHV1st MdIY5iUsjkpuQDvb46PFLIvSHZM9BivT+WmSr8whs/fG51StjZu2w/IzywMl5tQAglartQ8 USTFBq+tPSpfUbivRlkUIFKQVNKBifdEzaiD0bZ3e4MKRouI3wcUK9AF6OInPKQzhiHVOJs cIPDbTG4gMs9z8ouYqSnw== X-UI-Out-Filterresults: notjunk:1;V01:K0:TBKvT+OhVAo=:dvc/SBGhp2hgmOOQR2qKf3 aUbHT/7GydW91H4HTVcIlf/0CSzYPPtg5ajULJk3qhA0CwY13IlZ27eKKZr3RXaFp0Tmi2dsk mxM/15NsMBslSkP/kZ7vz3/wyHibk/hmPb6K+045czkQubgljiODDpEEIGGqDNDCOgt5E1TPZ DW0BjKtoULrVpF0Ip0FbJ0g92wPLKysZRTgeC+a39MQHYaTCBiiXLQn76jFyroOl9UHXgU4Nr WC+RBgeILQXtpDporE4pbeIVcG3z7IzQLa6H3jy+pJjN+SLydCalS4MImgQ5WigsHWzArN5/u je//m21cbKXfw1/bTZY7x+nnPvVElXjAmFlKHeQUQKy8zyMvVJz6//sEnU/uIo4LRXukBRyXf FU+mEZ28emA2bg7GzpZBGWYwwsUBrnjbTXiaDpuEnZbXpns2C2SgtwUNjL/wssneLO//QRjg4 Osa/JX1tna8fQ+5QEW8rTofIwqe1PZx1q/d/bIYGQyccYdtAy/+bZmRsJ4foK9UnDpD2YlfFn XBW3GnRLIXpKgh+mW+4nQKrK2F/+ZKBU6Wd1bPq8y2gy7Y2ywl5PAHcHo/M0ODKdfHJ4fTuIG khtspQyTkzQZ3jpp6XW6B8s+MhBJ+ajGZvJnatS39kQPJfwjSRBxeIvgPfSYSmtne4pOSfymQ FGRkrxX9leGj5qtBrTCHDUYjCS6sMCv1eAQukE8du5XvOf1Us6MaLaaL5HFNgtsz9i6xUSrY/ sgtRwYxqhyj+aoRrA9uq5c6F3iH4DHHf6AlaJWLnFXyOZuN+JSRReC4laGLWz8LZ2JEheQKq/ ehGYh4j Subject: Re: [Cake] making split_gso_threshold configurable X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Jul 2018 10:07:40 -0000 Hi Toke, > On Jul 25, 2018, at 12:02, Toke H=C3=B8iland-J=C3=B8rgensen = wrote: >=20 > Dave Taht writes: >=20 >> I really wanted cake to always optimize for low latency. I wanted it >> to "just work" at line rate on dsl, on 100mbit, even 10mbit ethernet, >> to work against pause frames, etc, without configuration. I wanted to >> defeat drivers like the mvneta that can do 64k of software GRO >> automagically. >=20 > So I think that Eric's point was that the GSO logic itself should > throttle back and not build so big packets when the link rate is = lower. > Might be worth it to check if this is actually the case, and if not to > get GSO fixed rather than disabling it. >=20 > Also, are there actually any modems that will negotiate ethernet line > rates less than a gigabit? Yes, there are XDSL Modem(routers) that only have fast-ethernet = ports. Not sure how rare these are though. Best Regards Sebastian >=20 >> Along the way to mainlining it, cake's behavior got changed, to scale >> well to 50Gbit by allowing GSO above a 1gbit shaped rate, and *always >> allowing GSO at line rate*. >>=20 >> if (q->rate_bps && q->rate_bps <=3D CAKE_SPLIT_GSO_THRESHOLD) >> q->rate_flags |=3D CAKE_FLAG_SPLIT_GSO; >> else >> q->rate_flags &=3D ~CAKE_FLAG_SPLIT_GSO; >>=20 >> I don't care about 50gbit. I'm delighted, even astonished, it does >> 50Gbit. I want it to do 1mbit with 13ms interpacket latency when hit >> by an IW10 burst from somewhere else, not 130, with hardware pause >> frames in use on the dsl modem or elsewhere. >=20 > Getting pause frames to work properly in this setup kinda requires the > buffering in the modem to be reasonable in the first place... >=20 >> so, I'd like to A) default to always split shaped or unshaped. And B) >> expose the split threshold to be configured via userspace. This = latter >> option would give a tunable for those struggling a bit for cpu to = play >> with, also. >=20 > I very much doubt that we can get upstream to accept split as the > default. It may be possible to get it to be user tunable. I don't = think > we should deviate from upstream unless we absolutely have to (that was > kinda the whole point of the upstreaming exercise), and I'm not > convinced that this is a good enough reason... >=20 > -Toke > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake