Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755519AbbLXKLT (ORCPT ); Thu, 24 Dec 2015 05:11:19 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:51793 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755416AbbLXKLO (ORCPT ); Thu, 24 Dec 2015 05:11:14 -0500 Date: Thu, 24 Dec 2015 02:11:11 -0800 From: Christoph Hellwig To: "Elliott, Robert (Persistent Memory)" Cc: Cholerae Hu , Dan Williams , Dave Chinner , Ted Tso , "adilger.kernel@dilger.ca" , "linux-nvdimm@lists.01.org" , "linux-ext4@vger.kernel.org" , "xfs@oss.sgi.com" , "linux-kernel@vger.kernel.org" Subject: Re: A blocksize problem about dax and ext4 Message-ID: <20151224101111.GA6438@infradead.org> References: <94D0CD8314A33A4D9D801C0FE68B40295BEC985F@G9W0745.americas.hpqcorp.net> <20151224000021.GU19802@dastard> <94D0CD8314A33A4D9D801C0FE68B40295BEC9CDD@G9W0745.americas.hpqcorp.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94D0CD8314A33A4D9D801C0FE68B40295BEC9CDD@G9W0745.americas.hpqcorp.net> User-Agent: Mutt/1.5.23 (2014-03-12) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 763 Lines: 15 On Thu, Dec 24, 2015 at 02:47:07AM +0000, Elliott, Robert (Persistent Memory) wrote: > > Did you mean that I should make the blocksize bigger until the mount > > command tell me that dax is enabled? > > To really use DAX, the filesystem block size must match the > system CPU's page size, which is probably 4096 bytes. No, it doesn't. File you use for DAX must be aligne at page size granularity. For XFS you could do this with the per-inode extent size hint for example even if the overall block size is smaller. -- 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/