From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-x242.google.com (mail-io0-x242.google.com [IPv6:2607:f8b0:4001:c06::242]) (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 D98A03B2B0 for ; Sun, 12 Jun 2016 14:19:09 -0400 (EDT) Received: by mail-io0-x242.google.com with SMTP id d2so7325027iof.1 for ; Sun, 12 Jun 2016 11:19:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:subject:from:to:cc:date:in-reply-to:references :mime-version:content-transfer-encoding; bh=zY683rqSRsU1FajRp5gJxfDej3BfU6rXOA6k/U7npRY=; b=cYJcX3WbhudIp9rXs87Mpy2gSWH0nTGPMGCv/xUbuFFMlRRU/UjaLJfKo22T1nS3uw WjGxiQoKl/BnPBq1iXUL47SqBd24Fil844UNSz7BjWRqDFkt66N8c5M0o2J+yClG8eBF 9hZZYxp4SW6T/armIANt9obfYuZTWWtht+rMn8WHoiesmSuaKu3sh6wWQMm4xhFYzRHn vJNF5/h+9W0+xU+X0lmBMli8OV7xAfbGhr/r0vtP3vttiqKWKuWt0cHC5zsi/3nVu2Yd u0A8vGwQJ3t1cVXzSlC7S16j89gYwMClApQ9sgmSCVKWIj8lYA9fqyIGt6Y3FWGysqQE 3BvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=zY683rqSRsU1FajRp5gJxfDej3BfU6rXOA6k/U7npRY=; b=SrnIvc1eAJ/bMA0fmlNWifUxtA7ICK0+IUnqmAn3OIbh4H6tnYpkk32goZhjqLLTRR ste82bkzbWqzXZOrw6vEiZhmCI52f196CyO7CrboQ0i/gYh3PdssUiPISQiGfOvLbJIq nyiO753TaGCebu3B7HTNPcc21Z3RZCZaXLLzUvdttGqiGH9o4/Da8tXqCiMUQqY3gSOu 1UMpwhobVJ5o4x4CMKDnnpJo47WdkhuclxvNtE5avffQTQj+lmppwBFJ3/S+/ROe0rZ2 v1OgO03LUtfPI5yYM2QPYge8OFdhg4Cczprlw9Nq4I3i5H+wVvrwVOfxb0FBJaHR8cMd un7g== X-Gm-Message-State: ALyK8tKnEQWZldwvjwP1Wy4kc1a3Il5t1mSGTWeZkjPRQCmNyizne2vljmasi2RgNypQNg== X-Received: by 10.107.175.227 with SMTP id p96mr16718499ioo.78.1465755549430; Sun, 12 Jun 2016 11:19:09 -0700 (PDT) Received: from [172.26.50.149] ([172.26.50.149]) by smtp.googlemail.com with ESMTPSA id o201sm10422651ioe.15.2016.06.12.11.19.08 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 12 Jun 2016 11:19:08 -0700 (PDT) Message-ID: <1465755547.7945.88.camel@edumazet-glaptop3.roam.corp.google.com> From: Eric Dumazet To: Jonathan Morton Cc: Dave Taht , cake@lists.bufferbloat.net Date: Sun, 12 Jun 2016 11:19:07 -0700 In-Reply-To: References: <5756ADEC.9070305@darbyshire-bryant.me.uk> <8EE35B4F-5C28-41C7-8795-93A6F606B3A8@gmail.com> <5756E2CA.2020700@darbyshire-bryant.me.uk> <575BD5D0.4060702@darbyshire-bryant.me.uk> <98AFD8C3-2343-4B8B-BFB0-6F877161A039@gmail.com> <1465749085.7945.81.camel@edumazet-glaptop3.roam.corp.google.com> <1465753733.7945.85.camel@edumazet-glaptop3.roam.corp.google.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: Re: [Cake] Possible BUG - parent backlog incorrectly updated in case of NET_XMIT_CN 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: Sun, 12 Jun 2016 18:19:10 -0000 On Sun, 2016-06-12 at 20:51 +0300, Jonathan Morton wrote: > > On 12 Jun, 2016, at 20:48, Eric Dumazet wrote: > > > >> A) In my failing to make sense of all the dialog around these patches > >> ( https://lwn.net/Articles/687617/ ), it sounds like this (inbound > >> and outbound) processing are still locked to a single thread, > >> essentially? > > > > Om a router, these discussions should not matter really, since the > > workload is about receiving/sending packets without user space > > intervention (well... I do hope this !) > > Dave’s point is that inbound and outbound processing could in > principle be on *two* distinct threads, potentially doubling aggregate > throughput in a CPU-limited environment. Only if IRQ were not properly tuned (smp_affinity) on SMP host. If you have one CPU, having two threads wont help, it will actually slow down a bit things. NAPI model already handles the 'one cpu, multiple queues/devices' quite well.