From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id DBEFF3B29D for ; Fri, 15 May 2020 16:38:51 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589575131; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=091kWnpkhoY8oOUGCScQ5eaPbNjHvQDeInNvBYD3Rkg=; b=EaxXpyRLnKrxGk42nPD6MreK6c0yB03I+0Vl1PA1giM3SOgDVcsHpxcxzpBKsikh9QVHye 5/aq0SflVsmNI/EbonyorferXHW8tkZbH9Cwk/ULTxvDiAh7B8tvtoLTPObGQ3YO9RNGbX KAf3pHxQYfmEPD++9uh4bdvaIKJjnVU= Received: from mail-lf1-f71.google.com (mail-lf1-f71.google.com [209.85.167.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-480-lv9Yq8bVMx6vKAgD1R9r8g-1; Fri, 15 May 2020 16:38:45 -0400 X-MC-Unique: lv9Yq8bVMx6vKAgD1R9r8g-1 Received: by mail-lf1-f71.google.com with SMTP id t11so1308262lfc.17 for ; Fri, 15 May 2020 13:38:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=091kWnpkhoY8oOUGCScQ5eaPbNjHvQDeInNvBYD3Rkg=; b=Uif+kSZr5qX4EWCYRV8oyqrcoVHDfva/ZcVU68rlpsOBO29Pji/LbF7fWV8IB8x5WJ 7ehe6B8S4tycFJPoJam5eRPAwWeKZDoO0TTWfNcTvMYJbLy16u9inmGrhcOj/WPFMdVC 7pVtKouku6o0xHYb5bvmGhOiA+GkuuwDEf7A8NpHXbpJmJwPmZ6mxvqGKxsyNwUgoaia zmVyXAxmfQw6cGbOIA4fB9YXgVIgm7VVFIEb638zT49Nyis3rIQq7DDCcbMHMhUf23/z 4/7HG9bOWaitQF9p7CrA0+lrYctoF2cDrOmI5SeHgREyTBeelelkFzGaogF9vxfm4yat FOOw== X-Gm-Message-State: AOAM530PYS7uWNwoia/phVuUQ68BICJaHvhs9JZPyf+lR8tcqBjSQOMM /QrGByZXm9UDw7BJj54Bs2rLBTlq2llOfvhq+GegwfDeoPld1+pezt/QHxHl9J3axvP02tc6i6N /PSo2v88gMyEJmE3U1sY3YwOuaI5ceQFEAx8= X-Received: by 2002:ac2:599b:: with SMTP id w27mr3506520lfn.164.1589575122129; Fri, 15 May 2020 13:38:42 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyoewU4U/Ra5SW9PiG+U27GMlINv/ROUG8HfGrB2BOPJx0SrhQNRX/oJxXk4TE6nI86izHxmA== X-Received: by 2002:ac2:599b:: with SMTP id w27mr3506513lfn.164.1589575121894; Fri, 15 May 2020 13:38:41 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id u24sm1672618ljl.28.2020.05.15.13.38.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 May 2020 13:38:41 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 49D6B181510; Fri, 15 May 2020 22:38:40 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Bob McMahon , Tim Higgins Cc: Make-Wifi-fast In-Reply-To: References: <56a03e99-3337-bf4a-4743-deb93abb9592@smallnetbuilder.com> <6d8fc82a-cd32-31ba-023c-4dcd7822bb1d@smallnetbuilder.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Fri, 15 May 2020 22:38:40 +0200 Message-ID: <87k11dq6gf.fsf@toke.dk> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Subject: Re: [Make-wifi-fast] SmallNetBuilder article: Does OFDMA Really Work? 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: Fri, 15 May 2020 20:38:51 -0000 Bob McMahon via Make-wifi-fast writes: > In that analogy, latency and bloat, while correlated, aren't the same > thing. I think by separating them one can better understand how a system > will perform. I suspect your tests with 120ms of latency are really > measuring bloat. Little's law is average queue depth = average effective > arrival rate * average service time. Bloat is mostly about excessive queue > depths and latency mostly about excessive service times. Since they affect > one another it's easy to conflate them. I'd say this is a bit of an odd definition? In my view, "latency" is the time it takes a packet to get from one place to another, and it can have many sources, one of which is bloat. For a rather comprehensive survey and categorisation of other sources, see [0]. As you say, bloat does tend to drown out other sources of latency, but that is a bug as far as I'm concerned. Once you fix that, looking at all the other sources becomes much easier. Optimising those other sources of latency is worthwhile too, of course, it just doesn't help as much until you also fix the bloat. -Toke [0] https://ieeexplore.ieee.org/abstract/document/6967689