From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:52051) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RdPWX-0008C4-Ak for qemu-devel@nongnu.org; Wed, 21 Dec 2011 12:00:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RdPWV-0005Qe-Lg for qemu-devel@nongnu.org; Wed, 21 Dec 2011 12:00:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:63645) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RdPWV-0005QW-85 for qemu-devel@nongnu.org; Wed, 21 Dec 2011 12:00:11 -0500 Message-ID: <4EF21093.6030408@redhat.com> Date: Wed, 21 Dec 2011 18:00:03 +0100 From: Paolo Bonzini MIME-Version: 1.0 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> <20111221165528.GA27101@lst.de> In-Reply-To: <20111221165528.GA27101@lst.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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: Christoph Hellwig Cc: Kevin Wolf , qemu-devel@nongnu.org, Stefan Hajnoczi On 12/21/2011 05:55 PM, Christoph Hellwig wrote: > 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. The physical_block_size doesn't matter? Paolo