From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <dev-bounces@dpdk.org> Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 37743A04AB; Wed, 6 Nov 2019 13:16:46 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 89C111C0DD; Wed, 6 Nov 2019 13:16:45 +0100 (CET) Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by dpdk.org (Postfix) with ESMTP id 7ADF11C0D7 for <dev@dpdk.org>; Wed, 6 Nov 2019 13:16:43 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Nov 2019 04:16:42 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,274,1569308400"; d="scan'208";a="212761357" Received: from aburakov-mobl1.ger.corp.intel.com (HELO [10.237.220.92]) ([10.237.220.92]) by fmsmga001.fm.intel.com with ESMTP; 06 Nov 2019 04:16:41 -0800 To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>, "dev@dpdk.org" <dev@dpdk.org>, "bruce.richardson@intel.com" <bruce.richardson@intel.com>, Olivier Matz <olivier.matz@6wind.com> References: <BYAPR18MB2424E2396F4B352EDC80488AC87F0@BYAPR18MB2424.namprd18.prod.outlook.com> From: "Burakov, Anatoly" <anatoly.burakov@intel.com> Message-ID: <4fe56f91-1817-3213-5e1a-19f85f5d83d8@intel.com> Date: Wed, 6 Nov 2019 12:16:40 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <BYAPR18MB2424E2396F4B352EDC80488AC87F0@BYAPR18MB2424.namprd18.prod.outlook.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] Limiting packet buffers under 4GB X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> Errors-To: dev-bounces@dpdk.org Sender: "dev" <dev-bounces@dpdk.org> On 04-Nov-19 12:59 PM, Jerin Jacob Kollanukkaran wrote: > Hi Anatoly and All, > > Just wondering what would the side effect of lowering a _bit_ of static uint64_t baseaddr = 0x100000000 in > lib/librte_eal/common/eal_common_memory.c for 64bit systems. > > Use case: > If we _reserve_ VA address which less than 2^32 ONLY for packet buffers(mbuf), The use cases like > Pipeline, where need to transfer packets from one core to another cores can use ring element > size of 4B(32bit) which will reduce the a lot of read and write to enable better > performance. > > i.e Since upper 32bits will be zero, it is matter of typecasting of item to read and write from/to ring. > Essentially memcpy overhead for moving pointers over the ring will be half. > > Is baseaddr set to 2^32 to make sure that secondary process will have more _chance_ of getting > the baseaddr in order for DPDK to work? > > Thoughts on above? On general to reduce the mbuf pointer storage requirement for ring? > You can already try that with --base-virtaddr option if you have such specific addressing requirements. That said, the address is pretty much arbitrary, so i'm not against lowering it in principle, it just feels like a workaround for something that's very specific to the workloads you are targetting. -- Thanks, Anatoly