From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id ECE1A8E72 for ; Tue, 12 Jan 2016 15:13:25 +0100 (CET) Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga101.jf.intel.com with ESMTP; 12 Jan 2016 06:13:25 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,557,1444719600"; d="scan'208";a="725414458" Received: from smonroyx-mobl.ger.corp.intel.com (HELO [10.237.221.28]) ([10.237.221.28]) by orsmga003.jf.intel.com with ESMTP; 12 Jan 2016 06:13:22 -0800 From: Sergio Gonzalez Monroy To: Pavel Fedin References: <1446748276-132087-1-git-send-email-jianfeng.tan@intel.com> <1452426182-86851-1-git-send-email-jianfeng.tan@intel.com> <1452426182-86851-3-git-send-email-jianfeng.tan@intel.com> <5694C36D.2040006@intel.com> <00d501d14d20$930c8ae0$b925a0a0$@samsung.com> <5694D9E9.6060704@intel.com> <00de01d14d28$7c2eaf80$748c0e80$@samsung.com> <5694DE7C.4050206@intel.com> <00e301d14d2d$ad9cb350$08d619f0$@samsung.com> <5694EDA4.9030202@intel.com> <00ed01d14d41$278cd8d0$76a68a70$@samsung.com> Message-ID: <56950A01.1010508@intel.com> Date: Tue, 12 Jan 2016 14:13:21 +0000 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <00ed01d14d41$278cd8d0$76a68a70$@samsung.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: nakajima.yoshihiro@lab.ntt.co.jp, "'Michael S. Tsirkin'" , dev@dpdk.org, ann.zhuangyanying@huawei.com Subject: Re: [dpdk-dev] [PATCH 2/4] mem: add API to obstain memory-backed file info 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: Tue, 12 Jan 2016 14:13:26 -0000 On 12/01/2016 13:57, Pavel Fedin wrote: > Hello! > >> I might be missing something obvious here but, aside from having memory >> SHARED which most DPDK apps using hugepages will have anyway, what is >> the backward compatibility issues that you see here? > Heh, sorry once again for confusing. Indeed, with hugepages we always get MAP_SHARED. I missed that. So, we indeed need > --shared-mem only in addition to --no-huge. > > Backwards compatibility issue is stated in the description of PATCH 1/4: > --- cut --- > b. possible ABI break, originally, --no-huge uses anonymous memory > instead of file-backed way to create memory. > --- cut --- > The patch unconditionally changes that to SHARED. That's all. I should read more carefully! Sorry about that, I thought you were the one with the ABI concerns. Regarding ABI, I don't think there is any ABI issue with the change, we just have our memory file-backed and SHARED but we do that when using hugepages so I don't think it would be a huge issue. But if folks have concerns about it, we could always keep old behavior by default and, as you suggest, introduce another option for changing the flag. Sergio > Kind regards, > Pavel Fedin > Senior Engineer > Samsung Electronics Research center Russia > >