From: David Lang Subject: Re: page fault scalability (ext3, ext4, xfs) Date: Wed, 14 Aug 2013 23:18:01 -0700 (PDT) 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: Andi Kleen , Theodore Ts'o , Dave Hansen , LKML , xfs@oss.sgi.com, Dave Hansen , Linux FS Devel , Jan Kara , "linux-ext4@vger.kernel.org" , Tim Chen To: Andy Lutomirski Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com List-Id: linux-ext4.vger.kernel.org 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 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs