Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 15 Jul 2002 11:18:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 15 Jul 2002 11:18:31 -0400 Received: from 209-166-240-202.cust.walrus.com.240.166.209.in-addr.arpa ([209.166.240.202]:64151 "EHLO ti3.telemetry-investments.com") by vger.kernel.org with ESMTP id ; Mon, 15 Jul 2002 11:18:30 -0400 Date: Mon, 15 Jul 2002 11:20:59 -0400 From: "Bill Rugolsky Jr." To: linux-kernel@vger.kernel.org Cc: Matthias Andree Subject: Re: [PATCH] 2.4.19-rc1/2.5.25 provide dummy fsync() routine for directories on NFS mounts Message-ID: <20020715112059.A2316@ti20> References: <20020715075221.GC21470@uncarved.com> <20020715133507.GF32155@merlin.emma.line.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.4i In-Reply-To: <20020715133507.GF32155@merlin.emma.line.org>; from matthias.andree@stud.uni-dortmund.de on Mon, Jul 15, 2002 at 03:35:07PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2535 Lines: 54 On Mon, Jul 15, 2002 at 03:35:07PM +0200, Matthias Andree wrote: > For the data of users not acquainted with kernel intrinsics, the way > things are now are most dangerous, and I'd really ask that Andrew > Morton's dirsync() patches (where still necessary) and tool patches > (chattr, mount) be deployed NOW and that -o dirsync (call it noasync for > compatibility) be the default. A safety-speed tradeoff should only > sacrifice safety at the explicit request and mke2fs should be told to > generate ext3fs by default NOW. Put dirsync in 2.4? Sure, good idea. Dangerous without it? To whom? Explain how it is dangerous? The journalling filesystems perform directory updates as transactions. It's dangerous to your MTA perhaps. Andrew Morton has bent over backwards to find and fix bugs in the synchronous write logic and to provide what you wanted, i.e., dirsync. He and Chris Mason fixed performance problems in ext3 and Reiserfs. Reread the thread -- you insisted repeatedly that you just wanted dirsync. Or was that just the opening gambit? > The argumentation that Linux leaves the choice of when to sync directory > data to the application is nice, but not more, and having this as tuning > option is fine, but to quote Wietse Venema "it's interesting to see that > out of the box, Linux handles logging more securely (sync writes) than > email (async directory updates)". And right he is. With all due respect to Wieste, that's nonsense: synchronous write in syslog or other logging facilities is a *userspace* policy issue. Default synchronous directory updates is a *kernel* policy issue. I don't have dirsync handy at the moment, so I can't test, but I have to ask: have you tried the simple (and IMHO devastating) benchmark that I posted back on 2001-08-02 comparing Linux to Solaris file creation, http://marc.theaimsgroup.com/?l=linux-kernel&m=99678208121947&w=2 i.e., copy a file tree (XFree86-4.1, 33027 files) with hard links. Recall: Solaris: 363.46s real 0.84s user 10.13s system Ext2: real 0m3.823s user 0m0.240s sys 0m3.570s Ext3: real 0m5.106s user 0m0.200s sys 0m3.700s "dirsync" gives you what you want; please mount /var (or wherever) -o dirsync and leave the kernel defaults as they are. Regards, Bill Rugolsky - 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/