From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-xd41.google.com (mail-io1-xd41.google.com [IPv6:2607:f8b0:4864:20::d41]) (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 148553B2A4; Mon, 1 Jun 2020 16:35:55 -0400 (EDT) Received: by mail-io1-xd41.google.com with SMTP id o5so8357396iow.8; Mon, 01 Jun 2020 13:35:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=P/EnesaXv45QQkopxW3klVlwa5wajILbHdcM6OC7ROw=; b=jFJNEQ1wOh86O5Xn0V+FDNYFdOTmuYZULC/Y4/Qn5pF1uxRZMgFO/5yRvs9uv3qfqD lY2sTa50MRF8qjPabj/NFSaDK5p5ipGuWsP2MLDxPfFV3X/h6SoHQsrHdwxxi5NkLlfN 0sNG9K5e9FmsDhhdzeenOXN4LyGynFgDTgH6XuL9jyUQvQGdlmDkcJGlL2ErEjZ2X8WV 7qRpyY0lIQB9nxVc9sIy8elRKRxmJymXFA2OUJVmBafbQsZnbQzkAYtqMKuQ453d7ba6 Er5wIYCzDkEQiAL9+JczSxJtJ59468lad/YTV79UYXZ+bPHX1sJbFgKDascSZHaBf3aM timA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=P/EnesaXv45QQkopxW3klVlwa5wajILbHdcM6OC7ROw=; b=c0Bmn5WuIH+X5CAulx6XxjyXbGGXTSpGPnqLC9cQtMKC7kVSN6+kyW7KCqCdRPjBNV sxspiKPXIIcU0IcKSi3C4Fm6UbFylUGlNOq8l/0XTFWJgrP0oMjeKLf1/aoI632svE/u 1C1QVE1mOyEy4cfROmtTcJ64AEs0dDAtCTnn8M9rKbdTxhPpWW3TmLEkzE2XIwOe7rdq suaH184YXi9LRA0vSFETwmrM92/Jo60nJKaxlNY3sTROm+K3sD9Ykjd/858TTruO7mCo sDWXTBb64Dzl3CTUtN4NHY+QrBu4QgO6DFlMGqXN/Hh6SwWIsSXGwLrNev8ZR8XZDbfM N6uA== X-Gm-Message-State: AOAM533k1gaWyfHRZZgRD8IPDTD31kyZ2bb9rCvhkEgllq4SeqW3N13P hRf78By23JmiRfjkPtLFQrabXJJPJRJUrYYBtoT1cHKv X-Google-Smtp-Source: ABdhPJzTKX3P9EZ6TV0iWfRc8ZZaVmOIlOPWeVN/J5NA0tPIzJ3yumDMt2GhE/YnVJKh7I6pnhGYkTlNNxy+rgGlgUE= X-Received: by 2002:a6b:5b02:: with SMTP id v2mr20725779ioh.161.1591043754610; Mon, 01 Jun 2020 13:35:54 -0700 (PDT) MIME-Version: 1.0 References: <18883.1591027117@localhost> In-Reply-To: <18883.1591027117@localhost> From: Dave Taht Date: Mon, 1 Jun 2020 13:35:42 -0700 Message-ID: To: Michael Richardson Cc: bloat , cerowrt-devel Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Cerowrt-devel] [Bloat] capacity awareness for the deadline scheduler X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 01 Jun 2020 20:35:55 -0000 On Mon, Jun 1, 2020 at 8:58 AM Michael Richardson wrote: > > > Dave Taht wrote: > > Gradually, people seem to be getting more and more about basic queu= e theory. > > https://lwn.net/SubscriberLink/821578/ef5d913a20977921/ > > Having skimmed the article, which seems to be mostly about CPU scheduling= , I > have a question. > > Does the availability of better *CPU* scheduling make it easier to do bet= ter > TCP pacing? Maybe that was your entire point? It wasn't my entire point, it's just that I'm pleased to see more and more progress in more people more deeply understanding kleinrocks work. as one example, pie's default rate estimator tends to go to hell in the presence of jitter - be it induced by cpu scheduling, offloads, pulling stuff off the rx ring, or putting it on the tx ring. A fixed version of pie is documented here: https://www.sciencedirect.com/science/article/abs/pii/S1389128619313775 . All I knew at the time pie was being developed was that it didn't work well with hw multiqueue, I was not aware the rate estimator problem was more general. it worries me that pie is being naively applied to cable modem tech as this problem does not show up in simple simulations. > > -- > ] Never tell me the odds! | ipv6 mesh netwo= rks [ > ] Michael Richardson, Sandelman Software Works | IoT architec= t [ > ] mcr@sandelman.ca http://www.sandelman.ca/ | ruby on rails= [ > --=20 "For a successful technology, reality must take precedence over public relations, for Mother Nature cannot be fooled" - Richard Feynman dave@taht.net CTO, TekLibre, LLC Tel: 1-831-435-0729