From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 820573979 for ; Wed, 18 Nov 2015 17:19:24 +0100 (CET) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP; 18 Nov 2015 08:18:39 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,313,1444719600"; d="scan'208";a="841595655" Received: from irsmsx109.ger.corp.intel.com ([163.33.3.23]) by fmsmga001.fm.intel.com with ESMTP; 18 Nov 2015 08:17:24 -0800 Received: from irsmsx103.ger.corp.intel.com ([169.254.3.13]) by IRSMSX109.ger.corp.intel.com ([169.254.13.96]) with mapi id 14.03.0248.002; Wed, 18 Nov 2015 16:13:33 +0000 From: "Richardson, Bruce" To: Stephen Hemminger , "Xie, Huawei" Thread-Topic: [dpdk-dev] [RFC PATCH 2/2] lib/librte_eal: Remove unnecessary hugepage zero-filling Thread-Index: AQHRIhpJdgn7SSp6+EKQv/+xCvgSOZ6h86lQ Date: Wed, 18 Nov 2015 16:13:32 +0000 Message-ID: <59AF69C657FD0841A61C55336867B5B035985B24@IRSMSX103.ger.corp.intel.com> References: <1447817231-10510-1-git-send-email-zhihong.wang@intel.com> <1447817231-10510-3-git-send-email-zhihong.wang@intel.com> <8F6C2BD409508844A0EFC19955BE094183467C@SHSMSX152.ccr.corp.intel.com> <20151118080013.3cad8f5b@samsung9> In-Reply-To: <20151118080013.3cad8f5b@samsung9> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.182] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [RFC PATCH 2/2] lib/librte_eal: Remove unnecessary hugepage zero-filling 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: Wed, 18 Nov 2015 16:19:25 -0000 > -----Original Message----- > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen Hemminger > Sent: Wednesday, November 18, 2015 4:00 PM > To: Xie, Huawei > Cc: dev@dpdk.org > Subject: Re: [dpdk-dev] [RFC PATCH 2/2] lib/librte_eal: Remove unnecessar= y > hugepage zero-filling >=20 > On Wed, 18 Nov 2015 12:07:54 +0000 > "Xie, Huawei" wrote: >=20 > > >>> The kernel fills new allocated (huge) pages with zeros. > > >>> DPDK just has to touch the pages to trigger the allocation. > > I think we shouldn't reply on the assumption that kernel has zeroed > > the memory. Kernel zeroes the memory mostly to avoid information > > leakage.It could also achieve this by setting each bit to 1. > > What we indeed need to check is later DPDK initialization code doesn't > > assume the memory has been zeroed. Otherwise zero only that part of > > the memory. Does this makes sense? >=20 > If all new pages are zero, why does DPDK have to pre-touch the pages at > all? The pages won't actually be mapped into the processes address space until a= ccessed.=20 /Bruce