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 C8957A0613 for ; Mon, 23 Sep 2019 14:07:09 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id C80C71BED0; Mon, 23 Sep 2019 14:07:08 +0200 (CEST) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by dpdk.org (Postfix) with ESMTP id 012CE1BECE for ; Mon, 23 Sep 2019 14:07:06 +0200 (CEST) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Sep 2019 05:07:05 -0700 X-IronPort-AV: E=Sophos;i="5.64,539,1559545200"; d="scan'208";a="179106490" Received: from bricha3-mobl.ger.corp.intel.com ([10.237.221.95]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Sep 2019 05:07:02 -0700 Date: Mon, 23 Sep 2019 14:06:59 +0200 From: Bruce Richardson To: Andrzej Ostruszka Cc: Thomas Monjalon , Ray Kinsella , dev@dpdk.org, Aaron Conole , Michael Santana , John McNamara , Marko Kovacevic , David Hunt , Vladimir Medvedkin , Robert Sanford , Erik Gabriel Carrillo , mattias.ronnblom@ericsson.com, stephen@networkplumber.org, Andrzej Ostruszka Message-ID: <20190923120658.GA2003@bricha3-MOBL.ger.corp.intel.com> References: <20190917075754.8310-1-amo@semihalf.com> <20190919151624.GA1999@bricha3-MOBL.ger.corp.intel.com> <1873473.QF300kEeir@xps> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) Subject: Re: [dpdk-dev] [PATCH v2 01/10] build: add an option to enable LTO build 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 Mon, Sep 23, 2019 at 02:03:35PM +0200, Andrzej Ostruszka wrote: > On 9/23/19 9:23 AM, Thomas Monjalon wrote: > [...] > > Please can we get some numbers to understand how longer it is? > > Below numbers are for make based (make -j8) clean build on my system: > > non-LTO > real: 144.56s, user:451.81s, sys:48.46s, CPU:346% > > LTO > real: 607.20s, user:2141.71s, sys:88.36s, CPU:367% > > So it is similar ~5x increase as Mattias has reported. Have not > measured it, but the lion share of that increase is due to linking of > 'test' apps. > Interesting. Do we want to explicitly not use lto for the test app? > I would vote for leaving LTO as an option - although I must admit I did > not get what Ray meant by saying: > > 20/09/2019 09:38, Ray Kinsella: > [...] > > I would just like to see it in or out, not another build time option. > > If "in or out" means "either accept the patches with LTO on and no > config option or reject them" then I disagree. Even if run time > improvements are questionable I find the additional link time warnings > beneficial and would like to have an easy way to turn them on when doing > final touches before pushing out. Looking at it from the meson build view-point, support for lto is built into the tool itself, so the support can't be removed as such - it will either result in a working build or not. Therefore, I'm for taking a patch to support lto in meson, whatever about supporting it through make etc. /Bruce