From: Eric Sandeen Subject: Re: Bug#605009: serious performance regression with ext4 Date: Mon, 29 Nov 2010 09:54:59 -0600 Message-ID: <4CF3CCD3.8040608@redhat.com> References: <20101126093257.23480.86900.reportbug@pluto.milchstrasse.xx> <20101129072930.GA7213@burratino> <20101129144436.GT2767@thunk.org> <201011291618.25084.bernd.schubert@fastmail.fm> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Ted Ts'o" , Jonathan Nieder , linux-ext4@vger.kernel.org To: Bernd Schubert Return-path: Received: from mx1.redhat.com ([209.132.183.28]:27395 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754528Ab0K2PzG (ORCPT ); Mon, 29 Nov 2010 10:55:06 -0500 In-Reply-To: <201011291618.25084.bernd.schubert@fastmail.fm> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 11/29/10 9:18 AM, Bernd Schubert wrote: > On Monday, November 29, 2010, Ted Ts'o wrote: >> By using sync_file_range() first, for all files, this forces the >> delayed allocation to be resolved, so all of the block bitmaps, inode >> data structures, etc., are updated. Then on the first fdatasync(), >> the resulting journal commit updates all of the block bitmaps and all >> of the inode table blocks(), and we're done. The subsequent >> fdatasync() calls become no-ops --- which the ftrace shell script will >> show. > > Wouldn't it make sense to modify ext4 or even the vfs to do that on close() > itself? Most applications expect the file to be on disk after a close anyway but those applications would be wrong. http://www.flamingspork.com/talks/ Eat My Data: How Everybody Gets File IO Wrong -Eric > and I also don't see a good reason why one should delay a disk write-back > after close any longer (well, there are exeption if the application is broken, > for example such as ha-logd used by pacemaker, which did for each line of logs > an open, seek, write, flush, close sequence..., but at least we have fixed > that in -hg now). > > > Cheers, > Bernd > -- > 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