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 DF0044F98 for ; Fri, 2 Mar 2018 03:36:35 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Mar 2018 18:36:34 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,409,1515484800"; d="scan'208";a="21936470" Received: from fmsmsx104.amr.corp.intel.com ([10.18.124.202]) by orsmga008.jf.intel.com with ESMTP; 01 Mar 2018 18:36:34 -0800 Received: from fmsmsx155.amr.corp.intel.com (10.18.116.71) by fmsmsx104.amr.corp.intel.com (10.18.124.202) with Microsoft SMTP Server (TLS) id 14.3.319.2; Thu, 1 Mar 2018 18:36:33 -0800 Received: from shsmsx152.ccr.corp.intel.com (10.239.6.52) by FMSMSX155.amr.corp.intel.com (10.18.116.71) with Microsoft SMTP Server (TLS) id 14.3.319.2; Thu, 1 Mar 2018 18:36:33 -0800 Received: from shsmsx103.ccr.corp.intel.com ([169.254.4.116]) by SHSMSX152.ccr.corp.intel.com ([169.254.6.130]) with mapi id 14.03.0319.002; Fri, 2 Mar 2018 10:36:31 +0800 From: "Tan, Jianfeng" To: "Stojaczyk, DariuszX" , "dev@dpdk.org" , Maxime Coquelin , "Burakov, Anatoly" , Yuanhan Liu CC: "Harris, James R" , Thomas Monjalon Thread-Topic: virtio with 2MB hugepages - bringing back single file segments Thread-Index: AdOxqqyA5D5OnZTzTTaCvVf8X7xKdgAFp4zw Date: Fri, 2 Mar 2018 02:36:30 +0000 Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] virtio with 2MB hugepages - bringing back single file segments 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: Fri, 02 Mar 2018 02:36:36 -0000 Hi Dariusz, > -----Original Message----- > From: Stojaczyk, DariuszX > Sent: Friday, March 2, 2018 6:41 AM > To: dev@dpdk.org; Tan, Jianfeng; Maxime Coquelin; Burakov, Anatoly; > Yuanhan Liu > Cc: Harris, James R; Thomas Monjalon > Subject: virtio with 2MB hugepages - bringing back single file segments >=20 > Hi, >=20 > I'm trying to make a vhost-user initiator built upon DPDK work with 2MB > hugepages. In the initiator we have to share all memory with the host > process, so it > can perform DMA. DPDK currently enforces having one descriptor per > hugepage and there's an artificial limit of shared descriptors in DPDK vh= ost- > user implementation (currently 8). Because of that, all DPDK vhost-user > initiators are practically limited to 1GB hugepages at the moment. We can > always increase the artificial descriptor limit, but then we're limited b= y > sendmsg() itself, which on Linux accepts no more than 253 descriptors. > However, could we increase the vhost-user implementation limit to - say - > 128, and bring back "single file segments" [1]? "Single file segments [1]" can help at the scenario that 2MB hugepages are = not too scatter; i.e., some pages are physically contiguous. But it cannot solve the issue completely (imagine the worst situation). Plus, it makes the memory part a little complex. So we are expecting it (with some other issues on memory part) being addres= sed completely by Anatoly's rework on memory. Thanks, Jianfeng