From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier Matz Subject: Re: rte_mbuf library likely()/unlikely() Date: Tue, 24 Jul 2018 09:29:15 +0200 Message-ID: <20180724072915.tc66rnjxx6lbbvb4@platinum> References: <98CBD80474FA8B44BF855DF32C47DC35B421EE@smartserver.smartshare.dk> <98CBD80474FA8B44BF855DF32C47DC35B421F1@smartserver.smartshare.dk> <1220B8CA-FF5E-4632-81E4-E2A5243005BF@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: Morten =?iso-8859-1?Q?Br=F8rup?= , Honnappa Nagarahalli , "dev@dpdk.org" To: "Wiles, Keith" Return-path: Received: from mail.droids-corp.org (zoll.droids-corp.org [94.23.50.67]) by dpdk.org (Postfix) with ESMTP id 4215231FC for ; Tue, 24 Jul 2018 09:29:24 +0200 (CEST) Content-Disposition: inline In-Reply-To: <1220B8CA-FF5E-4632-81E4-E2A5243005BF@intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi, On Mon, Jul 23, 2018 at 10:40:03PM +0000, Wiles, Keith wrote: > > > > On Jul 23, 2018, at 2:09 PM, Morten Brørup wrote: > > > > I haven't performance tested, but they are compiler branch prediction hints pointing out the most likely execution path, so I expect them to have a positive effect. > > We really need to make sure this provides any performance improvement and that means it needs to be tested on a number of systems. Can you please do some performance testing or see if we can get the guys doing DPDK performance testing to first give this a try? This area is very sensitive to tweaking. I agree we should be driven by performance improvements. I remember a discussion with Bruce on the ML saying that hardware branch predictors generally do a good job. Thanks, Olivier