From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f47.google.com (mail-pg0-f47.google.com [74.125.83.47]) by dpdk.org (Postfix) with ESMTP id D73B2137C for ; Sun, 20 Aug 2017 19:56:46 +0200 (CEST) Received: by mail-pg0-f47.google.com with SMTP id u191so12057452pgc.2 for ; Sun, 20 Aug 2017 10:56:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=IDBQE72xyAFh4jOBphMKqfcq/Hh0D10YFqAI9T3EBfk=; b=GGpWUdRPhvdudb3N+t5AuoCGO9IpLa+3zvbBaBYvVlT66NkidDOwY0UdC8AeNWFhJC l4fOWw38OT5KhFXnhu+Ydo694juFAMHi6BcfirtHEmI1msNY3xu2tsf405ojnqgy6wKE 0wPaWvzUjPJc3Cw6ig9Hzewo++SVNimroGQv1wY+VThe2F7hV3Gzlolqax3H4An/dzCF BuFKlqD1feGP3R3uBMHTFhfoJqY+W2mGMuj/EmAAJBSyElmlAPNzEfJYlwiP291pRVEq 3Z3gd5y2nRbAlIb374U0W3EI4oVQ99S7NDTkxqq+nOpkUZyICKnntrGs+NJpMhEr06DE U46g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=IDBQE72xyAFh4jOBphMKqfcq/Hh0D10YFqAI9T3EBfk=; b=ANIVHZxI4YNFVPwcbC35FF/4KdfaK1vWelcl4l71gRx5k9UP7hFC82epXjTmFm5xbe SoSM+AmH3155zRZkTPi9tOR+G6Z3PkvW9q6I4yD28AXM4ExIO+mu8a+g0ytBNCHGJbnX MnQHTEyEKjpPmTzWXQzzshL6XtCOnkLLOdgO+DHDTFItTepuDVQvKlyoRo7Zk8iTfojM dYNuLPhHRttt53dW7bz3XQDz08WoYk4v/hZZALa1zrJmrq7JQkO9lZKCr1RWmjD1k3AB SucIKfryiHGj8JTmvA+8d+7XG5DXaJZUNGfJDFAGdNSzGaAoTTexxXIWPdu8IiesjiYP JT9g== X-Gm-Message-State: AHYfb5iQUAKE9Ecr7UTPhxvRWziHN8yugc+db/WofymCkkU1wab2UVuy SV+gaaG/UuGzsofH X-Received: by 10.99.146.67 with SMTP id s3mr14250194pgn.130.1503251806039; Sun, 20 Aug 2017 10:56:46 -0700 (PDT) Received: from xeon-e3 (76-14-207-240.or.wavecable.com. [76.14.207.240]) by smtp.gmail.com with ESMTPSA id 74sm10443143pfv.155.2017.08.20.10.56.45 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 20 Aug 2017 10:56:45 -0700 (PDT) Date: Sun, 20 Aug 2017 10:56:38 -0700 From: Stephen Hemminger To: "Dorsett, Michal" Cc: "users@dpdk.org" Message-ID: <20170820105638.4d216f50@xeon-e3> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-users] movzbl in rte_eth_rx_burst X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 20 Aug 2017 17:56:47 -0000 On Sat, 19 Aug 2017 08:45:15 +0000 "Dorsett, Michal" wrote: > Hi, > > We are running dpdk 16.07. Below is a snippet from a perf annotate report of a CPU running a thread that constantly reads packets. > As you can see, the hottest instructruction is > > movzbl 0x10(%rcx),%r15d > > which, I believe, is referring to > > struct rte_eth_dev *dev = &rte_eth_devices[port_id]; > > > Can someone explain why this instruction is so costly, and how I can remedy this? Perf is not accurate on exact instruction. Your problem is that reading TSC causes a full pipeline stall on most x86 processors. https://archive.fosdem.org/2015/schedule/event/dpdk_performance/