From: Yongqiang Yang Subject: Re: [RFC] enable ext4 allocate blocks across group boundary Date: Thu, 15 Mar 2012 10:57:49 +0800 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Ext4 Developers List To: Robin Dong Return-path: Received: from mail-yx0-f174.google.com ([209.85.213.174]:42204 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752950Ab2COC5u convert rfc822-to-8bit (ORCPT ); Wed, 14 Mar 2012 22:57:50 -0400 Received: by yenl12 with SMTP id l12so2575595yen.19 for ; Wed, 14 Mar 2012 19:57:49 -0700 (PDT) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: 2012/3/15 Robin Dong : > =D4=DA 2012=C4=EA3=D4=C215=C8=D5 =C9=CF=CE=E78:52=A3=ACYongqiang Yang= =D0=B4=B5=C0=A3=BA >> Hello List, >> >> 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. 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 bloc= k >> 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. > > IMO, since the max size of one ext4-extent is just 128MB, maybe a > contiguous space > beyond a single block group can not be used efficiently. I do not think maximum of extent size limits the value of block allocation across group boundary. Actually, maximum of contiguous blocks is determined by block allocation strategy(multi block allocation, preallocation, group selection ...) rather than others. Given that ext4 is indirect mapped and uses current block allocation strategy, contiguous blocks is still same. Yongqiang. > >> >> >> Any ideas? >> >> -- >> Best Wishes >> Yongqiang Yang >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-ext4= " in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > -- > Best Regard > Robin Dong --=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