From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 91B25A04B1; Wed, 26 Aug 2020 18:41:31 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 02FFCAAB7; Wed, 26 Aug 2020 18:41:31 +0200 (CEST) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 9297458C4 for ; Wed, 26 Aug 2020 18:41:29 +0200 (CEST) IronPort-SDR: Lxj6hO7MM2jSkmGyF+YEN5scQNcFhgyaIqG5VrZE2ytM/8nLVMECUXvQxXiOVn4dhLBYGLUNSq t6cJmXLligmA== X-IronPort-AV: E=McAfee;i="6000,8403,9725"; a="156329883" X-IronPort-AV: E=Sophos;i="5.76,356,1592895600"; d="scan'208";a="156329883" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2020 09:41:28 -0700 IronPort-SDR: g1Ug+6pOFIbIUs+qYedSkn8k1QeAQHdVBM0naZ50udL/PqObYyj22WjOQsm/8o5ag7L2hjxPIk ZdI6UWs3J/NQ== X-IronPort-AV: E=Sophos;i="5.76,356,1592895600"; d="scan'208";a="474839735" Received: from bricha3-mobl.ger.corp.intel.com ([10.252.1.248]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-SHA; 26 Aug 2020 09:41:26 -0700 Date: Wed, 26 Aug 2020 17:41:23 +0100 From: Bruce Richardson To: Ferruh Yigit Cc: Dharmik Thakkar , dev@dpdk.org, nd@arm.com, Ed Czeck , Jerin Jacob Kollanukkaran Message-ID: <20200826164123.GC564@bricha3-MOBL.ger.corp.intel.com> References: <20200520032023.2649-2-dharmik.thakkar@arm.com> <20200714215108.22437-1-dharmik.thakkar@arm.com> <3092c394-29e2-df76-6b99-01022875cde6@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3092c394-29e2-df76-6b99-01022875cde6@intel.com> Subject: Re: [dpdk-dev] [PATCH 0/6] app/testpmd: add runtime config X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Wed, Aug 26, 2020 at 05:33:20PM +0100, Ferruh Yigit wrote: > On 7/14/2020 10:51 PM, Dharmik Thakkar wrote: > > Meson build system lacks support for > > CONFIG_RTE_TEST_PMD_RECORD_CORE_CYCLES and > > CONFIG_RTE_TEST_PMD_RECORD_BURST_STATS configuration options. > > > > One solution is to add these options within meson_options.txt > > > > Since adding these as runtime config causes no performance impact, > > Hi Dharmik, > > These are on the datapath, and even disable there will be additional > checks, isn't it expected to have some impact? Did you do any > measurements for it? > Branches that always predict the same way can be very cheap, and unless proven to be a problem, I'd see no issue with having a few on the datapath - especially if it just one or two per burst. If we start seeing a significant number, or ones that occur for every packet, then we perhaps need to be more cautious. I also think that using lots of different CFLAGS for turning things on and off is as bad - or even worse - than using the old build-time config options, just this time we don't have a single list of them somewhere! Therefore, I think we really need to start converting these to runtime options where we can. Regards, /Bruce