From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x243.google.com (mail-oi0-x243.google.com [IPv6:2607:f8b0:4003:c06::243]) (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 9393D3B2B0 for ; Sun, 12 Jun 2016 12:40:46 -0400 (EDT) Received: by mail-oi0-x243.google.com with SMTP id r4so21047156oib.1 for ; Sun, 12 Jun 2016 09:40:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=YRjwWr14xO0SUNvPOJKOHEcF6LRwpcbRa2RU5heY3ps=; b=ZxZddrDjhIke/eQTme8HvYGbKHEiu9uBMMxh5km4usRR1Hl/l0I9zCLJR2LoqxaT2E GjN7+FKgIttGboZi6571jONUcnhcPI/j5nTTVuOHPbPfFV9rcZokpz5ffy9iT/128h9D vxYxBu16oesKthfXq2GeBfw+RWHCiNAF7KwoawJ8Diq9CavzrBDoEGiv5xmqFd9xhYRc 7MMFhppRUFdjHhLan+d0nwo4wDym2Hj0bKNkyoYvt2Jeaw8li38EVE6g5i+sWpAcKRgQ gwz6WDZCjyJ8VyhtEqU77FbCezOyZrq1XZMQWNcIS3HUkN3752XmHYWK9By+m+P3FrUZ 9SDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=YRjwWr14xO0SUNvPOJKOHEcF6LRwpcbRa2RU5heY3ps=; b=ZtQBrxJY5S0Z5q+C8bK4vmxdTvSgJm8kx+GqWb4FYzE10+TpfINA2FijAMpOKyCKpq m2bbMbcvwClU4iS9IewW3mORQhXeWu7CW7lgvXl03ri9uk3wf3Lb93A0USLCSHDRxg6O bDABZ3hEBfQdGA6M7XXNC274WjqtCtJbzF6MU4m7eElwncfYApzwMKE7PiSpU8NjGnm9 R1ijgecNBvqaUvSJlIZncCfeaJlCfQw3wcGtzFc4OSyOvUN9vVTTDnBhK52N2DQ1vN3J +NbyrgMtaMU49sXqKPaw2d5xekqvd+UR3OqkF5e4mz5RNLDgvGNVgqWm/+/ibiCo1zQo 2GCw== X-Gm-Message-State: ALyK8tKXSJ+ZV5KK2ClOfAwDjUmXfPdojvGI0OHoo1w/mvS8M9wWTBC6tfmr9tXCL893VYHKyykt8mAMcskBQA== X-Received: by 10.157.15.151 with SMTP id d23mr5826166otd.49.1465749645974; Sun, 12 Jun 2016 09:40:45 -0700 (PDT) MIME-Version: 1.0 Received: by 10.202.229.210 with HTTP; Sun, 12 Jun 2016 09:40:45 -0700 (PDT) In-Reply-To: <1465749085.7945.81.camel@edumazet-glaptop3.roam.corp.google.com> 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> From: Dave Taht Date: Sun, 12 Jun 2016 09:40:45 -0700 Message-ID: To: Eric Dumazet Cc: Jonathan Morton , cake@lists.bufferbloat.net Content-Type: text/plain; charset=UTF-8 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 16:40:46 -0000 Eric: Quick side question (from trying to understand the qdisc locking fixes you recently landed in net-next) In the sqm-scripts, we are usually in a position where we are doing both inbound and outbound rate limiting (htb + fq_codel or cake). We typically run out of cpu or have mis-behavior on the inbound side, and the cpu bottleneck appears to be in ksoftirqd. 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? B) But you have eliminated lot of overhead in basic qdisc processing to much cpu benefit and we should consider backporting these changes to lede/openwrt (4.4)?