From: Bernd Schubert Subject: Re: [PATCH, RFC 0/3] Introduce new O_HOT and O_COLD flags Date: Fri, 20 Apr 2012 12:16:22 +0200 Message-ID: <4F913776.5080603@itwm.fraunhofer.de> References: <1334863211-19504-1-git-send-email-tytso@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, Ext4 Developers List To: "Theodore Ts'o" Return-path: In-Reply-To: <1334863211-19504-1-git-send-email-tytso@mit.edu> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On 04/19/2012 09:20 PM, Theodore Ts'o wrote: > As I had brought up during one of the lightning talks at the Linux > Storage and Filesystem workshop, I am interested in introducing two new > open flags, O_HOT and O_COLD. These flags are passed down to the > individual file system's inode operations' create function, and the file > system can use these flags as a hint regarding whether the file is > likely to be accessed frequently or not. > > In the future I plan to do further work on how ext4 would use these > flags, but I want to first get the ability to pass these flags plumbed > into the VFS layer and the code points for O_HOT and O_COLD reserved. > Ted, you still remember the directory-block read-ahead patches I sent last year for ext4 and which you declined, as it would add another mount parameter for ext4? http://www.digipedia.pl/usenet/thread/11916/24502/#post24502 If an application could use those flags to the file system (and then not only ext4, but any file system) to indicate a certain directory is important and frequently accessed, it would be simple to update those patches to work without another mount option. And while I updating our FhGFS meta data on disk layout to workaround the general problem we, we (and for example Lustre) are still affected the object-storage-side. Thanks, Bernd