From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from vsmta12-2.nsc.no (vip22scan.telenor.net [148.123.15.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 0CF613B29E for ; Mon, 9 Oct 2017 03:41:55 -0400 (EDT) Received: from [153.110.251.167] ([153.110.251.167:49033] helo=ilp-smtp01.man.cosng.net) by vsmta12-2.nsc.no (envelope-from ) (ecelerity 3.6.22.53981 r(Core:3.6.22.0)) with ESMTPS (cipher=DHE-RSA-AES256-GCM-SHA384) id 89/F6-31444-2482BD95; Mon, 09 Oct 2017 09:41:54 +0200 Received: from TNS-SKO-24-202.corp.telenor.no (TNS-SKO-24-202.corp.telenor.no [10.179.59.70]) by ilp-smtp01.man.cosng.net (Postfix) with ESMTP id 1015820228; Mon, 9 Oct 2017 09:41:54 +0200 (CEST) Received: from TNS-SKO-24-210.corp.telenor.no (10.179.59.78) by TNS-SKO-24-202.corp.telenor.no (10.179.59.70) with Microsoft SMTP Server (TLS) id 15.0.1263.5; Mon, 9 Oct 2017 09:41:54 +0200 Received: from TNS-SKO-24-208.corp.telenor.no (10.179.59.76) by TNS-SKO-24-210.corp.telenor.no (10.179.59.78) with Microsoft SMTP Server (TLS) id 15.0.1263.5; Mon, 9 Oct 2017 09:41:52 +0200 Received: from TNS-SKO-24-208.corp.telenor.no ([fe80::b024:7a41:ba33:25b6]) by TNS-SKO-24-208.corp.telenor.no ([fe80::b024:7a41:ba33:25b6%12]) with mapi id 15.00.1263.000; Mon, 9 Oct 2017 09:41:52 +0200 From: To: , Thread-Topic: [Bloat] emulating non-duplex media in linux qdiscs Thread-Index: AQHTQKGGRxQVosPuF0OG5PDP9gEiR6LbIhw8 Date: Mon, 9 Oct 2017 07:41:52 +0000 Message-ID: <1507534912438.44276@telenor.com> References: In-Reply-To: Accept-Language: nb-NO, en-US Content-Language: nb-NO X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.181.50.13] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-SCAN_VERDICT: inbox Subject: Re: [Bloat] emulating non-duplex media in linux qdiscs 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: Mon, 09 Oct 2017 07:41:56 -0000 Half duplex is the term you are looking for=0A= https://en.wikipedia.org/wiki/Duplex_(telecommunications)=0A= =0A= Simplex is one way communication like traditional AM radio.=0A= =0A= Within emulation I'm not sure how to set this up with qdiscs, but you can o= ften set the network interface to half duplex with ethtool. Not sure if thi= s solves your task though.=0A= =0A= -Erik=0A= =0A= ________________________________________=0A= Fra: Bloat p=E5 vegne av Dave Taht =0A= Sendt: 9. oktober 2017 03:54=0A= Til: bloat=0A= Emne: [Bloat] emulating non-duplex media in linux qdiscs=0A= =0A= I have been hacking away at netem for a while now in the hope that=0A= eventually - with a great deal more hacking - it could be used to more=0A= accurately emulate shared media like wifi and lte.=0A= =0A= (Some people try to describe these as simplex (which is not true=0A= because you can have multiple destinations), and they certainly are=0A= not duplex, so I tend to say non-duplex and still hope some better=0A= word emerges)=0A= =0A= So... one sticking point for me has been wanting to emulate the fact=0A= that on shared media, that you cannot transmit and receive at the same=0A= time; that these are "coupled" events, and what I'd like to be able to=0A= express might be something like:=0A= =0A= tc qdisc add dev eth0 root netem rate 100mbit coupled some_identifier=0A= ... some tc mirred magic for ifb here ...=0A= tc qdisc add dev ifb0 root netem rate 10mbit coupled the_same_identifier=0A= =0A= "some_identifier" would be a mutex of some sort, and I confess to=0A= not having much grip on the kernel outside of the net/sched directory.=0A= =0A= What facility would be best to try and leverage? It would be created=0A= (globally) on first use, ref-counted (thus destroyed when it goes to=0A= zero), atomically updated... posix shared memory seems too heavyweight=0A= to use....=0A= =0A= --=0A= =0A= Dave T=E4ht=0A= CEO, TekLibre, LLC=0A= http://www.teklibre.com=0A= Tel: 1-669-226-2619=0A= _______________________________________________=0A= Bloat mailing list=0A= Bloat@lists.bufferbloat.net=0A= https://lists.bufferbloat.net/listinfo/bloat=0A=