From: Andreas Dilger Subject: Re: [RFC] enable ext4 allocate blocks across group boundary Date: Wed, 14 Mar 2012 20:34:10 -0600 Message-ID: References: Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: Ext4 Developers List To: Yongqiang Yang Return-path: Received: from idcmail-mo1so.shaw.ca ([24.71.223.10]:33203 "EHLO idcmail-mo1so.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751070Ab2COCds (ORCPT ); Wed, 14 Mar 2012 22:33:48 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2012-03-14, at 6:52 PM, Yongqiang Yang wrote: > Here is a proposal to enable ext4 allocate blocks across group boundary. > > Now ext4 allocates blocks within a single block group by locking a > group. Flex_bg puts metadata blocks together, as a result,it > enlarges contiguous blocks. So we can enable ext4 allocate blocks > within a flex block group. Inode allocation takes group lock as block > allocation, I am not sure if we should allocate inode within single > group as before. > > If we do this, then the new group boundary will be flex block group > boundary. I am not sure if it is worth doing. The maximum extent size is the same as a single block group, so there is relatively little value in doing this, IMHO. Cheers, Andreas