From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:57491) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RdPRy-0006m5-Bt for qemu-devel@nongnu.org; Wed, 21 Dec 2011 11:55:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RdPRx-0004gS-EG for qemu-devel@nongnu.org; Wed, 21 Dec 2011 11:55:30 -0500 Received: from verein.lst.de ([213.95.11.211]:49878 helo=newverein.lst.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RdPRx-0004gM-1o for qemu-devel@nongnu.org; Wed, 21 Dec 2011 11:55:29 -0500 Date: Wed, 21 Dec 2011 17:55:28 +0100 From: Christoph Hellwig Message-ID: <20111221165528.GA27101@lst.de> References: <1323779840-4235-1-git-send-email-pbonzini@redhat.com> <4EE884BD.4090808@redhat.com> <4EE88CC3.7090903@redhat.com> <4EE890FF.1050004@redhat.com> <4EE89936.5030007@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4EE89936.5030007@redhat.com> Subject: Re: [Qemu-devel] [PATCH 00/17] Support mismatched host and guest logical block sizes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Kevin Wolf , Christoph Hellwig , qemu-devel@nongnu.org, Stefan Hajnoczi On Wed, Dec 14, 2011 at 01:40:22PM +0100, Paolo Bonzini wrote: > If the partitions are aligned, the OS will always issue aligned requests, > because file system blocks are already 4k. It won't nessecarily. For example XFS will do a fair amount of sub-blocksize I/O for metadata and the log. Note that if you tell XFS that the minimal_io_size is 4k it will at least align the log write to it, which is what really matters.