Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934266AbXEWSIm (ORCPT ); Wed, 23 May 2007 14:08:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758853AbXEWSIa (ORCPT ); Wed, 23 May 2007 14:08:30 -0400 Received: from ug-out-1314.google.com ([66.249.92.174]:29828 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762006AbXEWSI1 (ORCPT ); Wed, 23 May 2007 14:08:27 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:subject:from:to:cc:content-type:date:message-id:mime-version:x-mailer:content-transfer-encoding; b=C5myasVFhhya/GHF59MaxAZropV1cUvBgYQahzEsMF+qJMV28MXFSgKSbAfOeUSqNxLt28g2w77DXPNJy3hjxNNZ4kaPNBtnnZ7t8aobeRydwUxbgi7ZWb81k1NNp0RzxfTB1dcRqOx0gz4MOCvjON9MLKSbckDzi1UjdfC3k6I= Subject: [RFC 5/5] inode reservation v0.1 (next step working) From: coly To: linux-ext4 Cc: linux-kernel , linux-fsdevel Content-Type: text/plain Date: Thu, 24 May 2007 02:08:52 +0800 Message-Id: <1179943732.4179.56.camel@coly-t43.site> Mime-Version: 1.0 X-Mailer: Evolution 2.6.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1238 Lines: 31 >From the benchmark and the experimental inores patch on ext4, it can be found that inode reservation on ext4 is a good idea to be tried. One of the original idea of inode reservation is NOT modifying on-disk format. Current magic inode can make it, but use a magic inodes list to link each reserved inode block together is not a good idea. Indeed, this is a performance killer. 1, Therefor, group descriptor has to be modified to add a new member --- this new member records the lastest reserved inode in inode table of each block group. 2, Use rest room in magic inode (sizeof(ext4_inode) - sizeof(ext4_magic_inode)) to record other reserved inode blocks. This method can reduce number of magic inodes, which can minimize I/O for magic inodes. 3, Use magic inode cache. Most of the magic inode accessings are reading (not writing), therefore, caching can help to reduce most of the read I/O for magic inode. 4, Modify mke2fs to support new on-disk layout for inode reservation. Coly - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/