From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id BAC32A488 for ; Mon, 12 Mar 2018 17:01:34 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Mar 2018 09:01:33 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,462,1515484800"; d="scan'208";a="24972264" Received: from irsmsx109.ger.corp.intel.com ([163.33.3.23]) by orsmga006.jf.intel.com with ESMTP; 12 Mar 2018 09:01:31 -0700 Received: from irsmsx101.ger.corp.intel.com ([169.254.1.5]) by IRSMSX109.ger.corp.intel.com ([169.254.13.19]) with mapi id 14.03.0319.002; Mon, 12 Mar 2018 16:01:29 +0000 From: "Trahe, Fiona" To: Ahmed Mansour , "Verma, Shally" , "dev@dpdk.org" CC: "De Lara Guarch, Pablo" , "Athreya, Narayana Prasad" , "Gupta, Ashish" , "Sahu, Sunila" , "Challa, Mahipal" , "Jain, Deepak K" , Hemant Agrawal , "Roy Pledge" , Youri Querry , "fiona.trahe@gmail.com" , "Daly, Lee" , "Jozwiak, TomaszX" Thread-Topic: [dpdk-dev] [PATCH] compressdev: implement API - mbuf alternative Thread-Index: AdO6FqZGVQESVGJPRLukdFdKpdlnig== Date: Mon, 12 Mar 2018 16:01:29 +0000 Message-ID: <348A99DA5F5B7549AA880327E580B435893478BA@IRSMSX101.ger.corp.intel.com> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiNWEwYzRkZmUtYWIyZi00MTkzLWE0MGYtMTJiMGY0MTA4ZGQ5IiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX05UIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE2LjUuOS4zIiwiVHJ1c3RlZExhYmVsSGFzaCI6Imoyb0h3ejVON2w3M2tkdEZHNkVcL0tDa1duV2lLZEJIUWpoeXRMQU9OUjI0PSJ9 x-ctpclassification: CTP_NT dlp-product: dlpe-windows dlp-version: 11.0.0.116 dlp-reaction: no-action x-originating-ip: [163.33.239.181] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH] compressdev: implement API - mbuf alternative 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: , X-List-Received-Date: Mon, 12 Mar 2018 16:01:35 -0000 Hi Shally, Ahmed, and anyone else interested in compressdev, I mentioned last week that we've been exploring using something other than = mbufs to pass src/dst buffers to compressdev PMDs. Reasons: - mbuf data is limited to 64k-1 in each segment of a chained mbuf. Data fo= r compression can be greater and it would add cycles to have to break up into smaller= segments. - data may originate in mbufs, but is more likely, particularly for storag= e use-cases, to=20 originate in other data structures. - There's a 2 cache-line overhead for every segment in a chain, most of th= is data is network-related, not needed by compressdev So moving to a custom structure would minimise memory overhead, remove rest= riction on 64k-1 size and give more flexibility if compressdev ever needs a= ny comp-specific meta-data. We've come up with a compressdev-specific structure using the struct iovec = from sys/uio.h, which is commonly used by storage applications. This would = replace the src and dest mbufs in the op. I'll not include the code here - Pablo will push that to github shortly and= we'd appreciate review comments there. https://github.com/pablodelara/dpdk-draft-compressdev Just posting on the mailing list to give a heads-up and ensure this reaches= a wider audience than may see it on github. =20 Note : We also considered having no data structures in the op, instead the = application would supply a callback which the PMD would use to retrieve meta-data (virt= address, iova, length)=20 for each next segment as needed. While this is quite flexible and allow the= application to keep its data in its native structures, it's likely to cost more cycles. So we're not proposing this at the moment, but hope to benchmark it later w= hile the API is still experimental. General feedback on direction is welcome here on the mailing list. For feedback on the details of implementation we would appreciate comments = on github. Regards, Fiona.