From: Yongqiang Yang Subject: Re: [RFC] enable ext4 allocate blocks across group boundary Date: Thu, 15 Mar 2012 10:49:19 +0800 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Ext4 Developers List To: Andreas Dilger Return-path: Received: from mail-yw0-f46.google.com ([209.85.213.46]:36775 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752558Ab2COCtU convert rfc822-to-8bit (ORCPT ); Wed, 14 Mar 2012 22:49:20 -0400 Received: by yhmm54 with SMTP id m54so2624508yhm.19 for ; Wed, 14 Mar 2012 19:49:19 -0700 (PDT) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Mar 15, 2012 at 10:34 AM, Andreas Dilger wr= ote: > On 2012-03-14, at 6:52 PM, Yongqiang Yang wrote: >> Here is a proposal to enable ext4 allocate blocks across group bound= ary. >> >> Now ext4 allocates blocks within a single block group by locking a >> group. =A0 Flex_bg puts metadata blocks together, as a result,it >> enlarges contiguous blocks. =A0So we can enable ext4 allocate blocks >> within a flex block group. Inode allocation takes group lock as bloc= k >> allocation, =A0I am not sure if we should allocate inode within sing= le >> group as before. >> >> If we do this, then the new group boundary will be flex block group >> boundary. =A0I 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. nope. The value comes from 2 aspects: 1. the preallocation can preallocate much more space , 2. if tail blocks of a group and head blocks of the next group is free, then they can be treated as contiguous blocks. I had a rough look at the code, current code does not handle the situ= ation. Yongqiang. > > Cheers, Andreas > > > > > --=20 Best Wishes Yongqiang Yang -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html