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[209.132.180.67]) by mx.google.com with ESMTP id e129si66950294pgc.344.2019.08.13.17.57.12; Tue, 13 Aug 2019 17:57:28 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=pb3lAkxG; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726888AbfHNA4d (ORCPT + 99 others); Tue, 13 Aug 2019 20:56:33 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:8097 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726802AbfHNA4c (ORCPT ); Tue, 13 Aug 2019 20:56:32 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 13 Aug 2019 17:56:34 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Tue, 13 Aug 2019 17:56:31 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Tue, 13 Aug 2019 17:56:31 -0700 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 14 Aug 2019 00:56:31 +0000 Subject: Re: [RFC PATCH 2/2] mm/gup: introduce vaddr_pin_pages_remote() From: John Hubbard To: Ira Weiny CC: Andrew Morton , Christoph Hellwig , Dan Williams , Dave Chinner , Jan Kara , Jason Gunthorpe , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , LKML , , , References: <20190812015044.26176-1-jhubbard@nvidia.com> <20190812015044.26176-3-jhubbard@nvidia.com> <20190812234950.GA6455@iweiny-DESK2.sc.intel.com> <38d2ff2f-4a69-e8bd-8f7c-41f1dbd80fae@nvidia.com> <20190813210857.GB12695@iweiny-DESK2.sc.intel.com> X-Nvconfidentiality: public Message-ID: <90e5cd11-fb34-6913-351b-a5cc6e24d85d@nvidia.com> Date: Tue, 13 Aug 2019 17:56:31 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL104.nvidia.com (172.18.146.11) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1565744194; bh=B3YJYqlMW/Nxmi5w427DPkTLK+35GlKeQUmyIqwgbAQ=; h=X-PGP-Universal:Subject:From:To:CC:References:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=pb3lAkxG2jaq8faEuI4gHuG/y2mFdtVCVx2wmdFURM6MMK0LE9ZIfzarYhLjFCV9x I4qkXlCYNapn9xvrWYGT8UIP0jz4syBdNwjPk1H39QXcnI0Gcujrna5uWL444p2Td7 QgJ6MrmnfOwUGp8cxQb8YdzplLtomAmCwn9/a7C5dtEhAXO5qAkMN6EYWf1zUC0wVL BgjN6i4WEPA9KZhfpLPxwNp4vV9YMKUyONd1+nLDTmQ8Bl9vSy857RVNGNwatbrXGb MjqfA4UxaXhWLS5vVCExkS7Q53ivS9Pe0EBVBMhQjgJlmcG7M+rGIMqAJWMHluoAg3 niFswF6dhE7Og== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/13/19 5:51 PM, John Hubbard wrote: > On 8/13/19 2:08 PM, Ira Weiny wrote: >> On Mon, Aug 12, 2019 at 05:07:32PM -0700, John Hubbard wrote: >>> On 8/12/19 4:49 PM, Ira Weiny wrote: >>>> On Sun, Aug 11, 2019 at 06:50:44PM -0700, john.hubbard@gmail.com wrote: >>>>> From: John Hubbard >>> ... >> Finally, I struggle with converting everyone to a new call. It is more >> overhead to use vaddr_pin in the call above because now the GUP code is going >> to associate a file pin object with that file when in ODP we don't need that >> because the pages can move around. > > What if the pages in ODP are file-backed? > oops, strike that, you're right: in that case, even the file system case is covered. Don't mind me. :) >> >> This overhead may be fine, not sure in this case, but I don't see everyone >> wanting it. So now I see why you said that, but I will note that ODP hardware is rare, and will likely remain rare: replayable page faults require really special hardware, and after all this time, we still only have CPUs, GPUs, and the Mellanox cards that do it. That leaves a lot of other hardware to take care of. thanks, -- John Hubbard NVIDIA