From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-x233.google.com (mail-yw0-x233.google.com [IPv6:2607:f8b0:4002:c05::233]) (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 75B8B3B25D; Sun, 1 May 2016 16:55:43 -0400 (EDT) Received: by mail-yw0-x233.google.com with SMTP id o66so251911778ywc.3; Sun, 01 May 2016 13:55:43 -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=scvVrkMA4o99W6CdjtaaEhWBFcszUbc0EgZyXTThrGo=; b=OOyx/A6w5pBQJTtf8r2yZ7g3mXIH37ujJM47zoENnzYO4yWeHNtz4YPnZnO/W+rh1+ weCr6JotkCamwAxfA7H94cqxR0U6r/3DilzjDQZuxpn+s7mdJm2A6kT+EWz+axw3Dwcv T5u8rUw2dx07kQVLVnIKk89WckVrtiC1IQsydGicBvu9x+ill8GqCNB5fIxn1NIq3rU9 VlykcMWOuPqVPoTsjoz+bPc162menFwbPj2hAHjaPKeQrUiduK01bUNEl91MyLihoFA3 7bkl+PepTOrolV++pKmJgcwzbCpEtwnr119OsNX4P3b3/3Z1XRp7ZPcjWF1pToJzQ9+M hSYA== 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=scvVrkMA4o99W6CdjtaaEhWBFcszUbc0EgZyXTThrGo=; b=EMIWwpQp5ERKpS1sj1pXXDtXLQy4DX8UdoKHjNST6WfxnVf2jWQZhp1UUVw6ZS8bDY t9Vf+ifJkaYpJbFLrdlOC1Cqv7mPRgHU3BBbVCEIV0RgVbqw4fubdMysepsgLyQVA9YV ayAiWSLnzrptnd/LXUa9MNj5p+OtZtUTMyzxAq+LhGWjGfmOfOE/eHAQY21LEkkZmlPd rKFl9PiLkjchJywmiQfsR0HvdRHvr5JsPcX14Zvc+Qxz6FjSt/YjiYS42Hofi6VmtrSn 8Sjjrw2kiLHkcf3uLJ0G4/5SCq9izimZ4vxS9wN4n70bLMhqv2Got30RIKCWj0CLbj4E ThfQ== X-Gm-Message-State: AOPr4FVjLCDV3Qu/Kl9HAJiHPZl7P+8U9OUSO+MY+D53luEZJYTPf2X07b9sWrybwtIj+w== X-Received: by 10.129.95.11 with SMTP id t11mr19357020ywb.301.1462136143022; Sun, 01 May 2016 13:55:43 -0700 (PDT) Received: from [100.96.106.16] ([100.96.106.16]) by smtp.googlemail.com with ESMTPSA id t189sm13570107ywd.43.2016.05.01.13.55.41 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 01 May 2016 13:55:42 -0700 (PDT) Message-ID: <1462136140.5535.219.camel@edumazet-glaptop3.roam.corp.google.com> From: Eric Dumazet To: Jonathan Morton Cc: Dave Taht , make-wifi-fast@lists.bufferbloat.net, "codel@lists.bufferbloat.net" , ath10k Date: Sun, 01 May 2016 13:55:40 -0700 In-Reply-To: References: <1462125592.5535.194.camel@edumazet-glaptop3.roam.corp.google.com> <865DA393-262D-40B6-A9D3-1B978CD5F6C6@gmail.com> <1462128385.5535.200.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 X-Mailman-Approved-At: Mon, 02 May 2016 15:49:25 -0400 Subject: Re: [Make-wifi-fast] [Codel] fq_codel_drop vs a udp flood 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: Sun, 01 May 2016 20:55:43 -0000 On Sun, 2016-05-01 at 23:35 +0300, Jonathan Morton wrote: > > On 1 May, 2016, at 21:46, Eric Dumazet wrote: > > > > Optimizing the search function is not possible, unless you slow down the > > fast path. This was my design choice. > > I beg to differ. Cake iterates over the queues in the bulk and sparse > lists, rather than all queues full stop. That’s a straightforward > optimisation which covers the case in question here, and has no effect > on the fast path. Thats not going to help, sorry, if you have hundreds of flows in these queues. (I had 200 TCP_STREAM running in my test, plus one hostile UDP_STREAM) It is going to be _much_ slower, since you'll bring in cpu caches way more memory, while disc spinlock is held. Better have a known cost of 1 cache line miss per drop, instead of 200 cache line misses per drop. (4096 bytes to store q->backlogs[] array -> 64 cache lines. If we drop 64 skb per pass, this averages to 1 cache line miss per drop) Listen, I never thought people were going to use fq_codel in some hostile env. I simply designed it to be used in home routers, so I would not imagine someone would be trying to kill its own Internet connection. So I believe I will sent this patch as is to David Miller for inclusion.