From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.mhcomputing.net (master.mhcomputing.net [74.208.46.186]) by dpdk.org (Postfix) with ESMTP id 47F1E374C for ; Mon, 20 Apr 2015 18:23:13 +0200 (CEST) Received: by mail.mhcomputing.net (Postfix, from userid 1000) id B8DCC80BD84; Mon, 20 Apr 2015 09:21:41 -0700 (PDT) Date: Mon, 20 Apr 2015 09:21:41 -0700 From: Matthew Hall To: Ravi Kumar Iyer Message-ID: <20150420162141.GB20826@mhcomputing.net> References: <115e8a38d223487488d22a99f53cc926@GURMBXV03.AD.ARICENT.COM> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <115e8a38d223487488d22a99f53cc926@GURMBXV03.AD.ARICENT.COM> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] cost of reading tsc register X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Apr 2015 16:23:13 -0000 On Mon, Apr 20, 2015 at 02:37:53PM +0000, Ravi Kumar Iyer wrote: > We were doing some code optimizations , running DPDK based applications, and chanced upon the rte_rdtsc function [ to read tsc timestamp register value ] consuming cpu cycles of the order of 100clock cycles with a delta of upto 40cycles at times [ 60-140 cycles] > > We are actually building up a cpu intensive application which is also very clock cycle sensitive and this is impacting our implementation. > > To validate the same using a small/vanilla application we wrote a small code and tested on a single core. > Has anyone else faced a similar issue or are we doing something really atrocious here. What happened when you tried rte_rdtsc_precise ? Matthew.