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[156.151.31.85]) by mx.google.com with ESMTPS id d1si17984517pll.283.2019.02.20.06.09.40 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Feb 2019 06:09:40 -0800 (PST) Received-SPF: pass (google.com: domain of william.kucharski@oracle.com designates 156.151.31.85 as permitted sender) client-ip=156.151.31.85; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=LZuDjeiK; spf=pass (google.com: domain of william.kucharski@oracle.com designates 156.151.31.85 as permitted sender) smtp.mailfrom=william.kucharski@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x1KDxSls140229; Wed, 20 Feb 2019 14:07:33 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2018-07-02; bh=rbJOGLjYWQW8uYVwZDy7W7Nqo1LJ1spRGcKE6/GOpbg=; b=LZuDjeiK+IgpTj0JZgeWqodJlp7Ysv2uE3peX/GVv7OUjZPoQ3QCEU3xjaAPGGbRfVey 3x7u3cjCRQQhiq4TO9PgFCGMH5JFVbO0SK6Cbifp15nlYxoxn+d9XsHg26EIADRHy+JF fFVjsajYyKbEJuO73zBhQcykGEM5bwQ9vg27T0jzZgXMjCThqLdJJGQOaafFVjZZB0rT 6hS8B4C5MTAnMsaoqXHtmi57tWIKkgbXbFD2dN6E5BCySPexalTWsPrdnFLvBA5XSGLq DxDLuDKUo9E5DQUOwoxImFyvUqsMVymrzu3jzJKcLb3YuaSvjRAfsHUCrEO2hq47l3pS BQ== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2120.oracle.com with ESMTP id 2qpb5rhmqd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Feb 2019 14:07:33 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x1KE7VCQ021829 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Feb 2019 14:07:32 GMT Received: from abhmp0011.oracle.com (abhmp0011.oracle.com [141.146.116.17]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x1KE7UW5031308; Wed, 20 Feb 2019 14:07:31 GMT Received: from [192.168.0.110] (/73.243.10.6) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 20 Feb 2019 06:07:30 -0800 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.2\)) Subject: Re: [LSF/MM TOPIC ][LSF/MM ATTEND] Read-only Mapping of Program Text using Large THP Pages From: William Kucharski In-Reply-To: <20190220134454.GF12668@bombadil.infradead.org> Date: Wed, 20 Feb 2019 07:07:29 -0700 Cc: lsf-pc@lists.linux-foundation.org, Linux-MM , linux-fsdevel@vger.kernel.org Content-Transfer-Encoding: 7bit Message-Id: <07B3B085-C844-4A13-96B1-3DB0F1AF26F5@oracle.com> References: <379F21DD-006F-4E33-9BD5-F81F9BA75C10@oracle.com> <20190220134454.GF12668@bombadil.infradead.org> To: Matthew Wilcox X-Mailer: Apple Mail (2.3445.104.2) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9172 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902200102 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000152, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Feb 20, 2019, at 6:44 AM, Matthew Wilcox wrote: > > That interface would need to have some hint from the VFS as to what > range of file offsets it's looking for, and which page is the critical > one. Maybe that's as simple as passing in pgoff and order, where pgoff is > not necessarily aligned to 1< pass in start, end, critical. The order is especially important, as I think it's vital that the FS can tell the difference between a caller wanting 2M in PAGESIZE pages (something that could be satisfied by taking multiple trips through the existing readahead) or needing to transfer ALL the content for a 2M page as the fault can't be satisfied until the operation is complete. It also won't be long before reading 1G at a time to map PUD-sized pages becomes more important, plus the need to support various sizes in-between for architectures like ARM that support them (see the non-standard size THP discussion for more on that.) I'm also hoping the conference would have enough "mixer" time that MM folks can have a nice discussion with the FS folks to get their input - or at the very least these mail threads will get that ball rolling.