Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760204Ab3HOGSY (ORCPT ); Thu, 15 Aug 2013 02:18:24 -0400 Received: from mail.lang.hm ([64.81.33.126]:44364 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752763Ab3HOGSW (ORCPT ); Thu, 15 Aug 2013 02:18:22 -0400 Date: Wed, 14 Aug 2013 23:18:01 -0700 (PDT) From: David Lang X-X-Sender: dlang@asgard.lang.hm To: Andy Lutomirski cc: Dave Chinner , "Theodore Ts'o" , Dave Hansen , Dave Hansen , Linux FS Devel , xfs@oss.sgi.com, "linux-ext4@vger.kernel.org" , Jan Kara , LKML , Tim Chen , Andi Kleen Subject: Re: page fault scalability (ext3, ext4, xfs) In-Reply-To: Message-ID: References: <520BB9EF.5020308@linux.intel.com> <20130814194359.GA22316@thunk.org> <520BED7A.4000903@intel.com> <20130814230648.GD22316@thunk.org> <20130815011101.GA3572@thunk.org> <20130815021028.GM6023@dastard> <20130815060149.GP6023@dastard> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1102 Lines: 23 On Wed, 14 Aug 2013, Andy Lutomirski wrote: >> The big problem with this approach is that not doing the >> timestamp update on page faults is going to break the inode change >> version counting because for ext4, btrfs and XFS it takes a >> transaction to bump that counter. NFS needs to know the moment a >> file is changed in memory, not when it is written to disk. Also, NFS >> requires the change to the counter to be persistent over server >> failures, so it needs to be changed as part of a transaction.... > > NFS can do whatever it wants, although I suspect that even NFS can get > away with deferring cmtime updates. NFS already has to do syncs to make sure the data is safe on disk, have a flag that NFS can use to make the ctime safe, everyone else can get the performance improvement and NFS can have it's slow-but-safe approach. David Lang -- 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/