From: Yongqiang Yang Subject: Re: [RFC] enable ext4 allocate blocks across group boundary Date: Thu, 15 Mar 2012 12:15:22 +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-yx0-f174.google.com ([209.85.213.174]:42258 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750717Ab2COEPW convert rfc822-to-8bit (ORCPT ); Thu, 15 Mar 2012 00:15:22 -0400 Received: by yenl12 with SMTP id l12so2619685yen.19 for ; Wed, 14 Mar 2012 21:15:22 -0700 (PDT) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Mar 15, 2012 at 10:49 AM, Yongqiang Yang wrote: > On Thu, Mar 15, 2012 at 10:34 AM, Andreas Dilger = wrote: >> On 2012-03-14, at 6:52 PM, Yongqiang Yang wrote: >>> Here is a proposal to enable ext4 allocate blocks across group boun= dary. >>> >>> 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 block= s >>> within a flex block group. Inode allocation takes group lock as blo= ck >>> allocation, =A0I am not sure if we should allocate inode within sin= gle >>> 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 ther= e >> is relatively little value in doing this, IMHO. > nope. =A0The value comes from 2 aspects: 1. the preallocation can > preallocate much more space , 2. if =A0tail blocks of a group and hea= d > blocks of the next group is free, then they can be treated as > contiguous blocks. Here I meant they can be seen in buddy allocator. Yongqiang. > > =A0I had a rough look at the code, current code does not handle the s= ituation. > > Yongqiang. >> >> Cheers, Andreas >> >> >> >> >> > > > > -- > Best Wishes > Yongqiang Yang --=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