From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x235.google.com (mail-lf0-x235.google.com [IPv6:2a00:1450:4010:c07::235]) (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 792693BA8E for ; Thu, 26 Apr 2018 03:26:16 -0400 (EDT) Received: by mail-lf0-x235.google.com with SMTP id r125-v6so29173129lfe.2 for ; Thu, 26 Apr 2018 00:26:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=eFKM2ZFu8Z7m3VSvO/YqeWTIZzabDRpz1BjJLZ2/1A8=; b=MnS9VtvDf/0FGLMnNaVwvSq6rjkdduDbX+mAlcxmSNR03P+E15AhJPbd+Ued5xpVBa 6BZbRQOTVgSYXuXxqYGfZPqV5Uu01NzM0tNQTS1tk8sspIqYgXnukliBAlQb8q1f7GbJ bTZAdghkgHmL1LVFUh4pf9fWyR+9qHTreUcb+mVX1KcHBVwVI7U9Lr92Dqe+teh4kb5+ 2SFl34owIPHopx4W7+HRMOHVT9qVunn9JDRRmF863vnsls9DqBbYMoSHJku3r128hKpR cccM135TnPZnNPciSLWrF4g93lCFXYIyk3sjHvCs2EJZ7uDd5Udge5wHGKvQiZv8a6NP SGyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=eFKM2ZFu8Z7m3VSvO/YqeWTIZzabDRpz1BjJLZ2/1A8=; b=W/4OdANhI5qM6RwKtAzFPdlonJ0JLQqNLOGQdweitCPguVv1/l0UaUEss1PR+kNXff F9LDkrXeZPW8fjX77Ywc+zQxUe6jaU4OwXF1WUNvgOndXuGAHEFyNZCfY1/ZyMHS0205 ksZCsk3Cu0CA6eQToSxdDmCUQZ78rv7v2tY+b29S1GGPJqHrKKu4pvGEDleOq6x6S/aT 02fl7f0Krdbw+pJuhI7fsxlr4y7N76/EKZifSzEsZsWWc5WuTPMz7iXxt97dYyvDY9ZP TMHUphQYK4jrLORd3wAp4FzZPlBOg1j2ovLVMZhD8xgM/XF71w/+LvenqktUswoP2woB CY6g== X-Gm-Message-State: ALQs6tCa/kMMKQN7TAeOGZPBjHvvZ0kYN7P4yetnUR7Dw+U/66dxrMBO k9TUIHBwZI6XY/Ik+SDMV3M= X-Google-Smtp-Source: AB8JxZoqSiJGLKX27opV8gTJ2NIh66LWOqUeQtw8PWv75caKtOp+b6eoc5yZT5K1EO1JQ06kA1s6mg== X-Received: by 2002:a19:ec0a:: with SMTP id b10-v6mr13353543lfa.31.1524727575402; Thu, 26 Apr 2018 00:26:15 -0700 (PDT) Received: from [192.168.239.216] (83-245-234-255-nat-p.elisa-mobile.fi. [83.245.234.255]) by smtp.gmail.com with ESMTPSA id a21-v6sm4271750lfi.75.2018.04.26.00.26.14 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Apr 2018 00:26:14 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.3 \(3445.6.18\)) From: Jonathan Morton In-Reply-To: Date: Thu, 26 Apr 2018 10:26:12 +0300 Cc: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , "cake@lists.bufferbloat.net" Content-Transfer-Encoding: quoted-printable Message-Id: <46C6A124-61F3-4503-B310-C55D46597EED@gmail.com> References: <87vacf3th7.fsf@toke.dk> To: Kevin Darbyshire-Bryant X-Mailer: Apple Mail (2.3445.6.18) Subject: Re: [Cake] CAKE upstreaming - testers wanted, ACK filtering rescuers needed 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: Thu, 26 Apr 2018 07:26:16 -0000 > Genuine question: I have a superpacket circa 64K, this is a lump of = data in a tcp flow. I have another small VOIP packet, it=E2=80=99s = latency sensitive. If I split the super packet into individual 1.5K = packets as they would be on the wire, I can insert my VOIP packet at = suitable place in time such that jitter targets are not exceeded. If I = don=E2=80=99t split the super packet, surely I have to wait till the end = of the superpacket=E2=80=99s queue (for want of a better word) and = possibly exceed my latency target. That looks to me like =E2=80=98GSO/TSO= =E2=80=99 is potentially bad for interflow latencies. > What don=E2=80=99t I understand here? You have it exactly right. For some reason, Eric is failing to consider = the general case of flow-isolating queues at low link rates, and only = considering high-rate FIFOs. More to the point, at 64Kbps a maximal GSO packet can take 8 seconds to = clear, while an MTU packet takes less than a quarter second! - Jonathan Morton