From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x232.google.com (mail-pf0-x232.google.com [IPv6:2607:f8b0:400e:c00::232]) (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 96D283BA8E for ; Mon, 9 Oct 2017 16:21:52 -0400 (EDT) Received: by mail-pf0-x232.google.com with SMTP id d28so170077pfe.2 for ; Mon, 09 Oct 2017 13:21:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=3zj/Ab0rchITAQTPUsIeY22EGW88NnFwNvcnbZLNQ/4=; b=Gj8VW/EsMrhYf8Qg3Q3fVRW/JlnbeL5Ih/eaILze6eniZD3zWTKvwcY2gFMbtwxdhx SCz53eLnDk0kS0WnEhdJfkKJcqOkRzXTnrnGQQVxDuthnRc8OU8yK2HfHgSsp0vn1fnd wJEIL0JYNcaVAquUXxmGJ1Fi+R5q6Wj2j2UI//SlNPlKhNIcFhm+N8a3u1DWLkDXIMtH tzpMaY0ibpd9/QyCAS1CVjsMM7PUP3bQA4LE3oGztYwUw2IDUBVIXojTVDC/y3EJlMcH LdmZ3l9jWEH9+SO7C1lRJk3ltlqydsTk559yE7wolsntUsb+HborfMbyhDB3qioBoO9j ci1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=3zj/Ab0rchITAQTPUsIeY22EGW88NnFwNvcnbZLNQ/4=; b=AS2VCNh7oKnXZvpYOfH30ul0ybXNQharAngXA5qEZMLRJdRpyI9a9meS8UmhTxAIuS cyCWzIwDRQ09+EuAGjDVExO7c6TqCkkYbd99VDLXncnFR5/vdyY9PCK6DI6KJK2BwgLm FhZ0yGlq0srLipyS44PqaCAl/z7/ACiA0LCuyIT2onkWHWXXj8vLlFW5BcjUKt54KCC+ Shaogsjcb6jNEIXeBy1eFwPPqmWlYCT5iJjkGUhrqr9Ke6KxJcd2LnU4FLMN35gZpY5K oLwOyUc7KvkA20kI8yHl3IvQdRtqcBEXdWbJZ7AqgZJdGv5N/X+0H4etvcyTDMGE7Evu S0WA== X-Gm-Message-State: AMCzsaWe3sqrH9/U44ERvihNELyFdQIFMwf5nuuBU+qmOEGR1RQcOIN7 3nBXVS6zSzIKppyhMFT3DQyqvJzGS7D+DN659n+Ftw== X-Google-Smtp-Source: AOwi7QBN+hRce7F2F5eHeFynPEQf0Oyt7JFX06HLOCc3AOW/Fp9DoZdKDZ9oNN4Q9Pbn97Ww5Ky9YCUCIpkhifsWgr8= X-Received: by 10.101.77.137 with SMTP id p9mr10261032pgq.88.1507580511751; Mon, 09 Oct 2017 13:21:51 -0700 (PDT) MIME-Version: 1.0 Received: by 10.100.178.67 with HTTP; Mon, 9 Oct 2017 13:21:51 -0700 (PDT) In-Reply-To: References: From: Stephen Hemminger Date: Mon, 9 Oct 2017 13:21:51 -0700 Message-ID: To: Dave Taht Cc: bloat Content-Type: multipart/alternative; boundary="089e08250fc8dfa332055b22f0d1" 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 20:21:52 -0000 --089e08250fc8dfa332055b22f0d1 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, Oct 8, 2017 at 6:54 PM, Dave Taht wrote: > I have been hacking away at netem for a while now in the hope that > eventually - with a great deal more hacking - it could be used to more > accurately emulate shared media like wifi and lte. > > (Some people try to describe these as simplex (which is not true > because you can have multiple destinations), and they certainly are > not duplex, so I tend to say non-duplex and still hope some better > word emerges) > > So... one sticking point for me has been wanting to emulate the fact > that on shared media, that you cannot transmit and receive at the same > time; that these are "coupled" events, and what I'd like to be able to > express might be something like: > > tc qdisc add dev eth0 root netem rate 100mbit coupled some_identifier > ... some tc mirred magic for ifb here ... > tc qdisc add dev ifb0 root netem rate 10mbit coupled the_same_identifier > > "some_identifier" would be a mutex of some sort, and I confess to > not having much grip on the kernel outside of the net/sched directory. > > What facility would be best to try and leverage? It would be created > (globally) on first use, ref-counted (thus destroyed when it goes to > zero), atomically updated... posix shared memory seems too heavyweight > to use.... > > -- > > Dave T=C3=A4ht > CEO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-669-226-2619 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat Since qdisc only see output packets, maybe a overlay device (like a tunnel or vlan), would be closer to what you want. --089e08250fc8dfa332055b22f0d1 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Sun, Oct 8, 2017 at 6:54 PM, Dave Taht <dave.taht@gmail.com&g= t; wrote:
I have been hacking away= at netem for a while now in the hope that
eventually - with a great deal more hacking - it could be used to more
accurately emulate shared media like wifi and lte.

(Some people try to describe these as simplex (which is not true
because you can have multiple destinations), and they certainly are
not duplex, so I tend to say non-duplex and still hope some better
word emerges)

So... one sticking point for me has been wanting to emulate the fact
that on shared media, that you cannot transmit and receive at the same
time; that these are "coupled" events, and what I'd like to b= e able to
express might be something like:

tc qdisc add dev eth0 root netem rate 100mbit coupled some_identifier
... some tc mirred magic for ifb here ...
tc qdisc add dev ifb0 root netem rate 10mbit coupled the_same_identifier
"some_identifier" would be a mutex of some sort, and I confess to=
not having much grip on the kernel outside of the net/sched directory.

What facility would be best to try and leverage? It would be created
(globally) on first use, ref-counted (thus destroyed when it goes to
zero), atomically updated... posix shared memory seems too heavyweight
to use....

--

Dave T=C3=A4ht
CEO, TekLibre, LLC
ht= tp://www.teklibre.com
Tel: 1-669-226-2619
_______________________________________________
Bloat mailing list
Bloat@lists.bufferbloat.net<= /a>
https://lists.bufferbloat.net/listinfo/bloat

Since qdisc only see output pac= kets, maybe a overlay device (like a tunnel or vlan),
would be cl= oser to what you want.=C2=A0

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